Re: [RFC PATCH v4 05/12] media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface

Hi Jean-Michel,

Thank you for the patch.

On Thu, Feb 03, 2022 at 06:50:02PM +0100, Jean-Michel Hautbois wrote:

Add driver for the Unicam camera receiver block on BCM283x processors.
It is represented as two video device nodes: unicam-image and
unicam-embedded which are connected to an internal subdev (named
unicam-subdev) in order to manage streams routing.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Naushir Patuck <redacted>
Signed-off-by: Jean-Michel Hautbois <redacted>

---
v3 main changes:
  - Change code organization
  - Remove unused variables
  - Correct the fmt_meta functions
  - Rewrite the start/stop streaming
    - You can now start the image node alone, but not the metadata one
    - The buffers are allocated per-node
    - only the required stream is started, if the route exists and is
      enabled
  - Prefix the macros with UNICAM_ to not have too generic names
  - Drop colorspace support
    -> This is causing issues in the try-fmt v4l2-compliance test
  test VIDIOC_G_FMT: OK
	fail: v4l2-test-formats.cpp(363): colorspace >= 0xff
	fail: v4l2-test-formats.cpp(465): testColorspace(!node->is_io_mc, pix.pixelformat, pix.colorspace, pix.ycbcr_enc, pix.quantization)
  test VIDIOC_TRY_FMT: FAIL
	fail: v4l2-test-formats.cpp(363): colorspace >= 0xff
	fail: v4l2-test-formats.cpp(465): testColorspace(!node->is_io_mc, pix.pixelformat, pix.colorspace, pix.ycbcr_enc, pix.quantization)
  test VIDIOC_S_FMT: FAIL

v2: Remove the unicam_{info,debug,error} macros and use
dev_dbg/dev_err instead.
---
 MAINTAINERS                                   |    1 +
 drivers/media/platform/Kconfig                |    1 +
 drivers/media/platform/Makefile               |    2 +
 drivers/media/platform/bcm2835/Kconfig        |   21 +
 drivers/media/platform/bcm2835/Makefile       |    3 +
 .../media/platform/bcm2835/bcm2835-unicam.c   | 2586 +++++++++++++++++
 .../media/platform/bcm2835/vc4-regs-unicam.h  |  253 ++
 7 files changed, 2867 insertions(+)
 create mode 100644 drivers/media/platform/bcm2835/Kconfig
 create mode 100644 drivers/media/platform/bcm2835/Makefile
 create mode 100644 drivers/media/platform/bcm2835/bcm2835-unicam.c
 create mode 100644 drivers/media/platform/bcm2835/vc4-regs-unicam.h

I'd name the file bcm2835-unicam-regs.h.

s/formats/unicam_formats/

+	/* YUV Formats */
+	{
+		.fourcc		= V4L2_PIX_FMT_YUYV,
+		.code		= MEDIA_BUS_FMT_YUYV8_1X16,
+		.depth		= 16,
+		.csi_dt		= 0x1e,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_UYVY,
+		.code		= MEDIA_BUS_FMT_UYVY8_1X16,
+		.depth		= 16,
+		.csi_dt		= 0x1e,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_YVYU,
+		.code		= MEDIA_BUS_FMT_YVYU8_1X16,
+		.depth		= 16,
+		.csi_dt		= 0x1e,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_VYUY,
+		.code		= MEDIA_BUS_FMT_VYUY8_1X16,
+		.depth		= 16,
+		.csi_dt		= 0x1e,
+	}, {
+	/* RGB Formats */
+		.fourcc		= V4L2_PIX_FMT_RGB565, /* gggbbbbb rrrrrggg */
+		.code		= MEDIA_BUS_FMT_RGB565_1X16,
+		.depth		= 16,
+		.csi_dt		= 0x22,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_RGB24, /* rgb */
+		.code		= MEDIA_BUS_FMT_RGB888_1X24,
+		.depth		= 24,
+		.csi_dt		= 0x24,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_BGR24, /* bgr */
+		.code		= MEDIA_BUS_FMT_BGR888_1X24,
+		.depth		= 24,
+		.csi_dt		= 0x24,
+	}, {
+	/* Bayer Formats */
+		.fourcc		= V4L2_PIX_FMT_SBGGR8,
+		.code		= MEDIA_BUS_FMT_SBGGR8_1X8,
+		.depth		= 8,
+		.csi_dt		= 0x2a,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGBRG8,
+		.code		= MEDIA_BUS_FMT_SGBRG8_1X8,
+		.depth		= 8,
+		.csi_dt		= 0x2a,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGRBG8,
+		.code		= MEDIA_BUS_FMT_SGRBG8_1X8,
+		.depth		= 8,
+		.csi_dt		= 0x2a,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SRGGB8,
+		.code		= MEDIA_BUS_FMT_SRGGB8_1X8,
+		.depth		= 8,
+		.csi_dt		= 0x2a,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SBGGR10P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SBGGR10,
+		.code		= MEDIA_BUS_FMT_SBGGR10_1X10,
+		.depth		= 10,
+		.csi_dt		= 0x2b,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGBRG10P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGBRG10,
+		.code		= MEDIA_BUS_FMT_SGBRG10_1X10,
+		.depth		= 10,
+		.csi_dt		= 0x2b,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGRBG10P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGRBG10,
+		.code		= MEDIA_BUS_FMT_SGRBG10_1X10,
+		.depth		= 10,
+		.csi_dt		= 0x2b,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SRGGB10P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SRGGB10,
+		.code		= MEDIA_BUS_FMT_SRGGB10_1X10,
+		.depth		= 10,
+		.csi_dt		= 0x2b,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SBGGR12P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SBGGR12,
+		.code		= MEDIA_BUS_FMT_SBGGR12_1X12,
+		.depth		= 12,
+		.csi_dt		= 0x2c,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGBRG12P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGBRG12,
+		.code		= MEDIA_BUS_FMT_SGBRG12_1X12,
+		.depth		= 12,
+		.csi_dt		= 0x2c,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGRBG12P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGRBG12,
+		.code		= MEDIA_BUS_FMT_SGRBG12_1X12,
+		.depth		= 12,
+		.csi_dt		= 0x2c,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SRGGB12P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SRGGB12,
+		.code		= MEDIA_BUS_FMT_SRGGB12_1X12,
+		.depth		= 12,
+		.csi_dt		= 0x2c,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SBGGR14P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SBGGR14,
+		.code		= MEDIA_BUS_FMT_SBGGR14_1X14,
+		.depth		= 14,
+		.csi_dt		= 0x2d,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGBRG14P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGBRG14,
+		.code		= MEDIA_BUS_FMT_SGBRG14_1X14,
+		.depth		= 14,
+		.csi_dt		= 0x2d,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SGRBG14P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SGRBG14,
+		.code		= MEDIA_BUS_FMT_SGRBG14_1X14,
+		.depth		= 14,
+		.csi_dt		= 0x2d,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_SRGGB14P,
+		.unpacked_fourcc = V4L2_PIX_FMT_SRGGB14,
+		.code		= MEDIA_BUS_FMT_SRGGB14_1X14,
+		.depth		= 14,
+		.csi_dt		= 0x2d,
+	}, {
+	/*
+	 * 16 bit Bayer formats could be supported, but there is no CSI2
+	 * data_type defined for raw 16, and no sensors that produce it at
+	 * present.
+	 */

Write this as

	/* 16 bit Bayer formats could be supported. */

as these is a data type.

+
+	/* Greyscale formats */
+		.fourcc		= V4L2_PIX_FMT_GREY,
+		.code		= MEDIA_BUS_FMT_Y8_1X8,
+		.depth		= 8,
+		.csi_dt		= 0x2a,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_Y10P,
+		.unpacked_fourcc = V4L2_PIX_FMT_Y10,
+		.code		= MEDIA_BUS_FMT_Y10_1X10,
+		.depth		= 10,
+		.csi_dt		= 0x2b,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_Y12P,
+		.unpacked_fourcc = V4L2_PIX_FMT_Y12,
+		.code		= MEDIA_BUS_FMT_Y12_1X12,
+		.depth		= 12,
+		.csi_dt		= 0x2c,
+	}, {
+		.fourcc		= V4L2_PIX_FMT_Y14P,
+		.unpacked_fourcc = V4L2_PIX_FMT_Y14,
+		.code		= MEDIA_BUS_FMT_Y14_1X14,
+		.depth		= 14,
+		.csi_dt		= 0x2d,
+	},
+	/* Embedded data format */
+	{
+		.fourcc		= V4L2_META_FMT_8,
+		.code		= MEDIA_BUS_FMT_METADATA_8,
+		.depth		= 8,
+		.metadata_fmt	= 1,
+	}
+};
+
+struct unicam_buffer {
+	struct vb2_v4l2_buffer vb;
+	struct list_head list;
+};
+
+static inline struct unicam_buffer *to_unicam_buffer(struct vb2_buffer *vb)
+{
+	return container_of(vb, struct unicam_buffer, vb.vb2_buf);
+}
+
+struct unicam_node {
+	bool registered;
+	bool streaming;
+	unsigned int node_id;

This is assigned but never used. You can either drop the field, or
modify unicam_schedule_dummy_buffer() to use node->node_id. In the
second case I would also modify is_metadata_node() and is_image_node()
to use the node_id.

I would also rename the field to id. And then,

	if (node->id == UNICAM_METADATA_NODE)

isn't much longer than

	if (is_metadata_node(node))

so you could decide to drop the is_metadata_node() and is_image_node()
helpers if desired.

+	/* Source pad id on the subdev for this node */

	/* Source pad of the connected subdev */

+	unsigned int src_pad_id;
+	/* Pointer pointing to current v4l2_buffer */

	/* Pointer to the current v4l2_buffer */

Same below.

+	struct unicam_buffer *cur_frm;
+	/* Pointer pointing to next v4l2_buffer */
+	struct unicam_buffer *next_frm;
+	/* video capture */
+	const struct unicam_fmt *fmt;
+	/* Used to store current pixel format */
+	struct v4l2_format v_fmt;
+	/* Used to store current mbus frame format */
+	struct v4l2_mbus_framefmt m_fmt;

Used in a single location but never initialized.

+	/* Buffer queue used in video-buf */
+	struct vb2_queue buffer_queue;
+	/* Queue of filled frames */
+	struct list_head dma_queue;
+	/* IRQ lock for DMA queue */
+	spinlock_t dma_queue_lock;
+	/* lock used to access this structure */
+	struct mutex lock;
+	/* Identifies video device for this channel */
+	struct video_device video_dev;
+	/* Pointer to the parent handle */
+	struct unicam_device *dev;
+	struct media_pad pad;
+	struct media_pipeline pipe;

There's a single pipeline, store this in unicam_device.

+	/*
+	 * Dummy buffer intended to be used by unicam
+	 * if we have no other queued buffers to swap to.
+	 */
+	void *dummy_buf_cpu_addr;
+	dma_addr_t dummy_buf_dma_addr;
+
+	/* Stream connected */
+	u32 stream;

This is used in unicam_start_streaming() and unicam_stop_streaming()
only, and I wonder if it's needed. The links between the unicam subdev
and the video nodes carry a single stream each, right ? In that case I
think you can hardcode stream 0 there. Tomi could confirm.

+};
+
+struct unicam_device {
+	struct kref kref;
+
+	/* V4l2 specific parameters */
+	struct v4l2_async_subdev asd;

Not used.

+
+	/* peripheral base address */
+	void __iomem *base;
+	/* clock gating base address */
+	void __iomem *clk_gate_base;
+	/* lp clock handle */
+	struct clk *clock;
+	/* vpu clock handle */
+	struct clk *vpu_clock;
+	/* V4l2 device */
+	struct v4l2_device v4l2_dev;
+	struct media_device mdev;
+
+	/* parent device */
+	struct device *pdev;

Call it dev, pdev usually refers to a platform device.

+	/* subdevice async Notifier */
+	struct v4l2_async_notifier notifier;
+	unsigned int sequence;
+
+	/* ptr to  sub device */

I'd drop this comment, and quite a few of the other ones actually. This
just duplicates the next line without adding any information.

+	struct v4l2_subdev *sensor;
+
+	/* Internal subdev */
+	struct {
+		struct v4l2_subdev sd;
+		struct media_pad pads[UNICAM_SD_NUM_PADS];
+		bool streaming;
+	} subdev;
+
+	/* Remote pad pointer */
+	struct media_pad *remote_pad;

This will always be equal to UNICAM_SD_PAD_SOURCE_IMAGE, so you can use
UNICAM_SD_PAD_SOURCE_IMAGE instead. There's however a use for storing a
pointer to the sensor's source pad. You can rename the field to
sensor_pad and move it next to the sensor field. You could also organize
it as

	struct {
		struct v4l2_subdev *subdev;
		struct media_pad *pad;
	} sensor;

+
+	enum v4l2_mbus_type bus_type;
+	/*
+	 * Stores bus.mipi_csi2.flags for CSI2 sensors, or
+	 * bus.mipi_csi1.strobe for CCP2.
+	 */
+	unsigned int bus_flags;
+	unsigned int max_data_lanes;
+	unsigned int active_data_lanes;
+	bool sensor_embedded_data;

Set but never used, drop it.

+
+	struct unicam_node node[UNICAM_MAX_NODES];
+};
+
+static inline struct unicam_device *
+v4l2_device_to_unicam_device(struct v4l2_device *v4l2_dev)

As this is only used with notifier->v4l2_dev as a parameter, you could
name is notifier_to_unicam_device and use

	return container_of(notifier, struct unicam_device, notifier);

+{
+	return container_of(v4l2_dev, struct unicam_device, v4l2_dev);
+}
+
+static inline struct unicam_device *
+sd_to_unicam_device(struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct unicam_device, subdev.sd);
+}
+
+/* -----------------------------------------------------------------------------
+ * Misc helper functions
+ */
+
+static inline bool is_metadata_node(struct unicam_node *node)
+{
+	return node->video_dev.device_caps & V4L2_CAP_META_CAPTURE;
+}
+
+static inline bool is_image_node(struct unicam_node *node)
+{
+	return node->video_dev.device_caps & V4L2_CAP_VIDEO_CAPTURE;
+}
+
+/* Hardware access */
+static inline void unicam_clk_write(struct unicam_device *dev, u32 val)

Some of the unicam_device pointers are named dev, some are named unicam.
Let's standardize globally on one of the two.

+{
+	writel(val | 0x5a000000, dev->clk_gate_base);
+}
+
+static inline u32 unicam_reg_read(struct unicam_device *dev, u32 offset)
+{
+	return readl(dev->base + offset);
+}
+
+static inline void unicam_reg_write(struct unicam_device *dev, u32 offset, u32 val)
+{
+	writel(val, dev->base + offset);
+}
+
+static inline int unicam_get_field(u32 value, u32 mask)
+{
+	return (value & mask) >> __ffs(mask);
+}
+
+static inline void unicam_set_field(u32 *valp, u32 field, u32 mask)
+{
+	u32 val = *valp;
+
+	val &= ~mask;
+	val |= (field << __ffs(mask)) & mask;
+	*valp = val;
+}
+
+static inline void unicam_reg_write_field(struct unicam_device *dev, u32 offset,
+					  u32 field, u32 mask)
+{
+	u32 val = unicam_reg_read(dev, offset);
+
+	unicam_set_field(&val, field, mask);
+	unicam_reg_write(dev, offset, val);
+}
+
+/* -----------------------------------------------------------------------------
+ * Format data table and helper functions
+ */
+
+/* Format setup functions */
+static const struct unicam_fmt *find_format_by_code(u32 code)

unicam_ prefix, and for the next two functions too.

+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(formats); i++) {
+		if (formats[i].code == code)
+			return &formats[i];
+	}
+
+	return NULL;
+}
+
+static const struct unicam_fmt *find_format_by_fourcc(u32 fourcc)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
+		if (formats[i].fourcc == fourcc)
+			return &formats[i];
+	}
+
+	return NULL;
+}
+
+static unsigned int bytes_per_line(u32 width, const struct unicam_fmt *fmt,
+				   u32 v4l2_fourcc)
+{
+	if (v4l2_fourcc == fmt->unpacked_fourcc)
+		/* Repacking always goes to 16bpp */

s/Repacking/Unpacking/

+		return ALIGN(width << 1, UNICAM_BPL_ALIGNMENT);
+	else
+		return ALIGN((width * fmt->depth) >> 3, UNICAM_BPL_ALIGNMENT);
+}
+
+static int unicam_calc_format_size_bpl(struct unicam_device *dev,
+				       const struct unicam_fmt *fmt,
+				       struct v4l2_format *f)
+{
+	unsigned int min_bytesperline;

min_bpl would be shorter to write.

+
+	v4l_bound_align_image(&f->fmt.pix.width, UNICAM_MIN_WIDTH, UNICAM_MAX_WIDTH, 2,
+			      &f->fmt.pix.height, UNICAM_MIN_HEIGHT, UNICAM_MAX_HEIGHT, 0,
+			      0);

Unless it hurts readability, the general rule is to keep lines within
the 80 columns limit in the media subsystem. I'd wrap this to 80
columns.

	v4l_bound_align_image(&f->fmt.pix.width, UNICAM_MIN_WIDTH,
			      UNICAM_MAX_WIDTH, 2,
			      &f->fmt.pix.height, UNICAM_MIN_HEIGHT,
			      UNICAM_MAX_HEIGHT, 0, 0);

There are other candidates for line wrap below.

+
+	min_bytesperline = bytes_per_line(f->fmt.pix.width, fmt,
+					  f->fmt.pix.pixelformat);

You could inline bytes_per_line() here as it's only used in this
location.

	/* Unpacking always goes to 16bpp */
	if (f->fmt.pix.pixelformat == fmt->unpacked_fourcc)
		min_bytesperline = width * 2;
	else
		min_bytesperline = width * fmt->depth / 8;
	min_bytesperline = ALIGN(min_bytesperline, UNICAM_BPL_ALIGNMENT);

+
+	if (f->fmt.pix.bytesperline > min_bytesperline &&
+	    f->fmt.pix.bytesperline <= UNICAM_MAX_BYTESPERLINE)
+		f->fmt.pix.bytesperline = ALIGN(f->fmt.pix.bytesperline,
+						UNICAM_BPL_ALIGNMENT);
+	else
+		f->fmt.pix.bytesperline = min_bytesperline;

Would this be clearer ?

	f->fmt.pix.bytesperline = ALIGN(f->fmt.pix.bytesperline,
					UNICAM_BPL_ALIGNMENT);
	f->fmt.pix.bytesperline = clamp(f->fmt.pix.bytesperline,
					min_bytesperline,
					UNICAM_MAX_BYTESPERLINE);

+
+	f->fmt.pix.sizeimage = f->fmt.pix.height * f->fmt.pix.bytesperline;
+
+	dev_dbg(dev->v4l2_dev.dev, "%s: fourcc: %08X size: %dx%d bpl:%d img_size:%d\n",

width and height are unsigned, so I'd use %ux%u. Same for bpl and
img_size.

You can use dev->pdev instead of dev->v4l2_dev.dev here and everywhere
else.

+		__func__,
+		f->fmt.pix.pixelformat,
+		f->fmt.pix.width, f->fmt.pix.height,
+		f->fmt.pix.bytesperline, f->fmt.pix.sizeimage);
+
+	return 0;
+}
+
+/* -----------------------------------------------------------------------------
+ * Hardware handling
+ */
+
+static void unicam_wr_dma_addr(struct unicam_device *dev, dma_addr_t dmaaddr,
+			       unsigned int buffer_size, int node_id)

Maybe you could pass a unicam_node pointer to replace dev and node_id ?

+{
+	dma_addr_t endaddr = dmaaddr + buffer_size;
+
+	if (node_id == UNICAM_IMAGE_NODE) {
+		unicam_reg_write(dev, UNICAM_IBSA0, dmaaddr);
+		unicam_reg_write(dev, UNICAM_IBEA0, endaddr);
+	} else {
+		unicam_reg_write(dev, UNICAM_DBSA0, dmaaddr);
+		unicam_reg_write(dev, UNICAM_DBEA0, endaddr);
+	}
+}
+
+static unsigned int unicam_get_lines_done(struct unicam_device *dev)
+{
+	dma_addr_t start_addr, cur_addr;
+	unsigned int stride = dev->node[UNICAM_IMAGE_NODE].v_fmt.fmt.pix.bytesperline;
+	struct unicam_buffer *frm = dev->node[UNICAM_IMAGE_NODE].cur_frm;
+
+	if (!frm)
+		return 0;
+
+	start_addr = vb2_dma_contig_plane_dma_addr(&frm->vb.vb2_buf, 0);
+	cur_addr = unicam_reg_read(dev, UNICAM_IBWP);
+	return (unsigned int)(cur_addr - start_addr) / stride;
+}
+
+static void unicam_schedule_next_buffer(struct unicam_node *node)
+{
+	struct unicam_device *dev = node->dev;
+	struct unicam_buffer *buf;
+	unsigned int size;
+	dma_addr_t addr;
+
+	buf = list_first_entry(&node->dma_queue, struct unicam_buffer, list);
+	node->next_frm = buf;
+	list_del(&buf->list);
+
+	addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
+	if (is_image_node(node)) {
+		size = node->v_fmt.fmt.pix.sizeimage;
+		unicam_wr_dma_addr(dev, addr, size, UNICAM_IMAGE_NODE);
+	} else {
+		size = node->v_fmt.fmt.meta.buffersize;
+		unicam_wr_dma_addr(dev, addr, size, UNICAM_METADATA_NODE);
+	}
+}
+
+static void unicam_schedule_dummy_buffer(struct unicam_node *node)
+{
+	struct unicam_device *dev = node->dev;
+	int node_id = is_image_node(node) ? UNICAM_IMAGE_NODE : UNICAM_METADATA_NODE;
+
+	dev_dbg(dev->v4l2_dev.dev, "Scheduling dummy buffer for node %d\n", node_id);
+
+	unicam_wr_dma_addr(dev, node->dummy_buf_dma_addr, UNICAM_DUMMY_BUF_SIZE,
+			   node_id);
+	node->next_frm = NULL;
+}
+
+static void unicam_process_buffer_complete(struct unicam_node *node,
+					   unsigned int sequence)
+{
+	node->cur_frm->vb.field = node->m_fmt.field;

m_fmt is never initialized (and I don't think it should be, the subdev
use the active state managed by the V4L2 core). I think this should be
node->v_fmt.field.

+	node->cur_frm->vb.sequence = sequence;
+
+	vb2_buffer_done(&node->cur_frm->vb.vb2_buf, VB2_BUF_STATE_DONE);
+}
+
+static void unicam_queue_event_sof(struct unicam_device *unicam)
+{
+	struct v4l2_event event = {
+		.type = V4L2_EVENT_FRAME_SYNC,
+		.u.frame_sync.frame_sequence = unicam->sequence,
+	};
+
+	v4l2_event_queue(&unicam->node[UNICAM_IMAGE_NODE].video_dev, &event);
+}
+
+/*
+ * unicam_isr : ISR handler for unicam capture
+ * @irq: irq number
+ * @dev_id: dev_id ptr
+ *
+ * It changes status of the captured buffer, takes next buffer from the queue
+ * and sets its address in unicam registers
+ */
+static irqreturn_t unicam_isr(int irq, void *dev)
+{
+	struct unicam_device *unicam = dev;
+	unsigned int lines_done = unicam_get_lines_done(dev);
+	unsigned int sequence = unicam->sequence;
+	unsigned int i;
+	u32 ista, sta;
+	bool fe;
+	u64 ts;
+
+	sta = unicam_reg_read(unicam, UNICAM_STA);
+	/* Write value back to clear the interrupts */
+	unicam_reg_write(unicam, UNICAM_STA, sta);
+
+	ista = unicam_reg_read(unicam, UNICAM_ISTA);
+	/* Write value back to clear the interrupts */
+	unicam_reg_write(unicam, UNICAM_ISTA, ista);
+
+	dev_dbg(unicam->v4l2_dev.dev, "ISR: ISTA: 0x%X, STA: 0x%X, sequence %d, lines done %d",
+		ista, sta, sequence, lines_done);
+
+	if (!(sta & (UNICAM_IS | UNICAM_PI0)))
+		return IRQ_HANDLED;
+
+	/*
+	 * Look for either the Frame End interrupt or the Packet Capture status
+	 * to signal a frame end.
+	 */
+	fe = ista & UNICAM_FEI || sta & UNICAM_PI0;
+
+	/*
+	 * We must run the frame end handler first. If we have a valid next_frm
+	 * and we get a simultaneout FE + FS interrupt, running the FS handler
+	 * first would null out the next_frm ptr and we would have lost the
+	 * buffer forever.
+	 */
+	if (fe) {
+		/*
+		 * Ensure we have swapped buffers already as we can't
+		 * stop the peripheral. If no buffer is available, use a
+		 * dummy buffer to dump out frames until we get a new buffer
+		 * to use.
+		 */
+		for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
+			if (!unicam->node[i].streaming)
+				continue;
+
+			/*
+			 * If cur_frm == next_frm, it means we have not had
+			 * a chance to swap buffers, likely due to having
+			 * multiple interrupts occurring simultaneously (like FE
+			 * + FS + LS). In this case, we cannot signal the buffer
+			 * as complete, as the HW will reuse that buffer.
+			 */
+			if (unicam->node[i].cur_frm &&
+			    unicam->node[i].cur_frm != unicam->node[i].next_frm)
+				unicam_process_buffer_complete(&unicam->node[i],
+							       sequence);
+			unicam->node[i].cur_frm = unicam->node[i].next_frm;
+		}
+		unicam->sequence++;
+	}
+
+	if (ista & UNICAM_FSI) {
+		/*
+		 * Timestamp is to be when the first data byte was captured,
+		 * aka frame start.
+		 */
+		ts = ktime_get_ns();
+		for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
+			if (!unicam->node[i].streaming)
+				continue;
+
+			if (unicam->node[i].cur_frm)
+				unicam->node[i].cur_frm->vb.vb2_buf.timestamp =
+								ts;
+			else
+				dev_dbg(unicam->v4l2_dev.dev, "ISR: [%d] Dropping frame, buffer not available at FS\n",
+					i);

				dev_dbg(unicam->v4l2_dev.dev,
					"ISR: [%d] Dropping frame, buffer not available at FS\n",
					i);

+			/*
+			 * Set the next frame output to go to a dummy frame
+			 * if we have not managed to obtain another frame
+			 * from the queue.
+			 */
+			unicam_schedule_dummy_buffer(&unicam->node[i]);
+		}
+
+		unicam_queue_event_sof(unicam);
+	}
+
+	/*
+	 * Cannot swap buffer at frame end, there may be a race condition
+	 * where the HW does not actually swap it if the new frame has
+	 * already started.
+	 */
+	if (ista & (UNICAM_FSI | UNICAM_LCI) && !fe) {
+		for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
+			if (!unicam->node[i].streaming)
+				continue;
+
+			spin_lock(&unicam->node[i].dma_queue_lock);
+			if (!list_empty(&unicam->node[i].dma_queue) &&
+			    !unicam->node[i].next_frm)
+				unicam_schedule_next_buffer(&unicam->node[i]);
+			spin_unlock(&unicam->node[i].dma_queue_lock);
+		}
+	}
+
+	if (unicam_reg_read(unicam, UNICAM_ICTL) & UNICAM_FCM) {
+		/* Switch out of trigger mode if selected */
+		unicam_reg_write_field(unicam, UNICAM_ICTL, 1, UNICAM_TFC);
+		unicam_reg_write_field(unicam, UNICAM_ICTL, 0, UNICAM_FCM);
+	}
+	return IRQ_HANDLED;
+}
+
+static void unicam_set_packing_config(struct unicam_device *dev)
+{
+	u32 pack, unpack;
+	u32 val;
+
+	if (dev->node[UNICAM_IMAGE_NODE].v_fmt.fmt.pix.pixelformat ==
+	    dev->node[UNICAM_IMAGE_NODE].fmt->fourcc) {
+		unpack = UNICAM_PUM_NONE;
+		pack = UNICAM_PPM_NONE;
+	} else {
+		switch (dev->node[UNICAM_IMAGE_NODE].fmt->depth) {
+		case 8:
+			unpack = UNICAM_PUM_UNPACK8;
+			break;
+		case 10:
+			unpack = UNICAM_PUM_UNPACK10;
+			break;
+		case 12:
+			unpack = UNICAM_PUM_UNPACK12;
+			break;
+		case 14:
+			unpack = UNICAM_PUM_UNPACK14;
+			break;
+		case 16:
+			unpack = UNICAM_PUM_UNPACK16;
+			break;
+		default:
+			unpack = UNICAM_PUM_NONE;
+			break;
+		}
+
+		/* Repacking is always to 16bpp */
+		pack = UNICAM_PPM_PACK16;
+	}
+
+	val = 0;
+	unicam_set_field(&val, unpack, UNICAM_PUM_MASK);
+	unicam_set_field(&val, pack, UNICAM_PPM_MASK);
+	unicam_reg_write(dev, UNICAM_IPIPE, val);
+}
+
+static void unicam_cfg_image_id(struct unicam_device *dev)
+{

	struct unicam_node *node = &dev->node[UNICAM_IMAGE_NODE];

will help shorten the lines below. There could be other functoins where
this could be useful.

+	if (dev->bus_type == V4L2_MBUS_CSI2_DPHY) {
+		/* CSI2 mode, hardcode VC 0 for now. */
+		unicam_reg_write(dev, UNICAM_IDI0,
+				 (0 << 6) | dev->node[UNICAM_IMAGE_NODE].fmt->csi_dt);
+	} else {
+		/* CCP2 mode */
+		unicam_reg_write(dev, UNICAM_IDI0,
+				 0x80 | dev->node[UNICAM_IMAGE_NODE].fmt->csi_dt);
+	}
+}
+
+static void unicam_enable_ed(struct unicam_device *dev)
+{
+	u32 val = unicam_reg_read(dev, UNICAM_DCS);
+
+	unicam_set_field(&val, 2, UNICAM_EDL_MASK);
+	/* Do not wrap at the end of the embedded data buffer */
+	unicam_set_field(&val, 0, UNICAM_DBOB);
+
+	unicam_reg_write(dev, UNICAM_DCS, val);
+}
+
+static void unicam_start_rx(struct unicam_device *dev, dma_addr_t *addr)
+{
+	int line_int_freq = dev->node[UNICAM_IMAGE_NODE].v_fmt.fmt.pix.height >> 2;
+	unsigned int size, i;
+	u32 val;
+
+	if (line_int_freq < 128)
+		line_int_freq = 128;
+
+	/* Enable lane clocks */
+	val = 1;
+	for (i = 0; i < dev->active_data_lanes; i++)
+		val = val << 2 | 1;
+	unicam_clk_write(dev, val);
+
+	/* Basic init */
+	unicam_reg_write(dev, UNICAM_CTRL, UNICAM_MEM);
+
+	/* Enable analogue control, and leave in reset. */
+	val = UNICAM_AR;
+	unicam_set_field(&val, 7, UNICAM_CTATADJ_MASK);
+	unicam_set_field(&val, 7, UNICAM_PTATADJ_MASK);
+	unicam_reg_write(dev, UNICAM_ANA, val);
+	usleep_range(1000, 2000);
+
+	/* Come out of reset */
+	unicam_reg_write_field(dev, UNICAM_ANA, 0, UNICAM_AR);
+
+	/* Peripheral reset */
+	unicam_reg_write_field(dev, UNICAM_CTRL, 1, UNICAM_CPR);
+	unicam_reg_write_field(dev, UNICAM_CTRL, 0, UNICAM_CPR);
+
+	unicam_reg_write_field(dev, UNICAM_CTRL, 0, UNICAM_CPE);
+
+	/* Enable Rx control. */
+	val = unicam_reg_read(dev, UNICAM_CTRL);
+	if (dev->bus_type == V4L2_MBUS_CSI2_DPHY) {
+		unicam_set_field(&val, UNICAM_CPM_CSI2, UNICAM_CPM_MASK);
+		unicam_set_field(&val, UNICAM_DCM_STROBE, UNICAM_DCM_MASK);
+	} else {
+		unicam_set_field(&val, UNICAM_CPM_CCP2, UNICAM_CPM_MASK);
+		unicam_set_field(&val, dev->bus_flags, UNICAM_DCM_MASK);
+	}
+	/* Packet framer timeout */
+	unicam_set_field(&val, 0xf, UNICAM_PFT_MASK);
+	unicam_set_field(&val, 128, UNICAM_OET_MASK);
+	unicam_reg_write(dev, UNICAM_CTRL, val);
+
+	unicam_reg_write(dev, UNICAM_IHWIN, 0);
+	unicam_reg_write(dev, UNICAM_IVWIN, 0);
+
+	/* AXI bus access QoS setup */
+	val = unicam_reg_read(dev, UNICAM_PRI);
+	unicam_set_field(&val, 0, UNICAM_BL_MASK);
+	unicam_set_field(&val, 0, UNICAM_BS_MASK);
+	unicam_set_field(&val, 0xe, UNICAM_PP_MASK);
+	unicam_set_field(&val, 8, UNICAM_NP_MASK);
+	unicam_set_field(&val, 2, UNICAM_PT_MASK);
+	unicam_set_field(&val, 1, UNICAM_PE);
+	unicam_reg_write(dev, UNICAM_PRI, val);
+
+	unicam_reg_write_field(dev, UNICAM_ANA, 0, UNICAM_DDL);
+
+	/* Always start in trigger frame capture mode (UNICAM_FCM set) */
+	val = UNICAM_FSIE | UNICAM_FEIE | UNICAM_FCM | UNICAM_IBOB;
+	unicam_set_field(&val, line_int_freq, UNICAM_LCIE_MASK);
+	unicam_reg_write(dev, UNICAM_ICTL, val);
+	unicam_reg_write(dev, UNICAM_STA, UNICAM_STA_MASK_ALL);
+	unicam_reg_write(dev, UNICAM_ISTA, UNICAM_ISTA_MASK_ALL);
+
+	/* tclk_term_en */
+	unicam_reg_write_field(dev, UNICAM_CLT, 2, UNICAM_CLT1_MASK);
+	/* tclk_settle */
+	unicam_reg_write_field(dev, UNICAM_CLT, 6, UNICAM_CLT2_MASK);
+	/* td_term_en */
+	unicam_reg_write_field(dev, UNICAM_DLT, 2, UNICAM_DLT1_MASK);
+	/* ths_settle */
+	unicam_reg_write_field(dev, UNICAM_DLT, 6, UNICAM_DLT2_MASK);
+	/* trx_enable */
+	unicam_reg_write_field(dev, UNICAM_DLT, 0, UNICAM_DLT3_MASK);
+
+	unicam_reg_write_field(dev, UNICAM_CTRL, 0, UNICAM_SOE);
+
+	/* Packet compare setup - required to avoid missing frame ends */
+	val = 0;
+	unicam_set_field(&val, 1, UNICAM_PCE);
+	unicam_set_field(&val, 1, UNICAM_GI);
+	unicam_set_field(&val, 1, UNICAM_CPH);
+	unicam_set_field(&val, 0, UNICAM_PCVC_MASK);
+	unicam_set_field(&val, 1, UNICAM_PCDT_MASK);
+	unicam_reg_write(dev, UNICAM_CMP0, val);
+
+	/* Enable clock lane and set up terminations */
+	val = 0;
+	if (dev->bus_type == V4L2_MBUS_CSI2_DPHY) {
+		/* CSI2 */
+		unicam_set_field(&val, 1, UNICAM_CLE);
+		unicam_set_field(&val, 1, UNICAM_CLLPE);
+		if (dev->bus_flags & V4L2_MBUS_CSI2_CONTINUOUS_CLOCK) {
+			unicam_set_field(&val, 1, UNICAM_CLTRE);
+			unicam_set_field(&val, 1, UNICAM_CLHSE);
+		}
+	} else {
+		/* CCP2 */
+		unicam_set_field(&val, 1, UNICAM_CLE);
+		unicam_set_field(&val, 1, UNICAM_CLHSE);
+		unicam_set_field(&val, 1, UNICAM_CLTRE);
+	}
+	unicam_reg_write(dev, UNICAM_CLK, val);
+
+	/*
+	 * Enable required data lanes with appropriate terminations.
+	 * The same value needs to be written to UNICAM_DATn registers for
+	 * the active lanes, and 0 for inactive ones.
+	 */
+	val = 0;
+	if (dev->bus_type == V4L2_MBUS_CSI2_DPHY) {
+		/* CSI2 */
+		unicam_set_field(&val, 1, UNICAM_DLE);
+		unicam_set_field(&val, 1, UNICAM_DLLPE);
+		if (dev->bus_flags & V4L2_MBUS_CSI2_CONTINUOUS_CLOCK) {
+			unicam_set_field(&val, 1, UNICAM_DLTRE);
+			unicam_set_field(&val, 1, UNICAM_DLHSE);
+		}
+	} else {
+		/* CCP2 */
+		unicam_set_field(&val, 1, UNICAM_DLE);
+		unicam_set_field(&val, 1, UNICAM_DLHSE);
+		unicam_set_field(&val, 1, UNICAM_DLTRE);
+	}
+	unicam_reg_write(dev, UNICAM_DAT0, val);
+
+	if (dev->active_data_lanes == 1)
+		val = 0;
+	unicam_reg_write(dev, UNICAM_DAT1, val);
+
+	if (dev->max_data_lanes > 2) {
+		/*
+		 * Registers UNICAM_DAT2 and UNICAM_DAT3 only valid if the
+		 * instance supports more than 2 data lanes.
+		 */
+		if (dev->active_data_lanes == 2)
+			val = 0;
+		unicam_reg_write(dev, UNICAM_DAT2, val);
+
+		if (dev->active_data_lanes == 3)
+			val = 0;
+		unicam_reg_write(dev, UNICAM_DAT3, val);
+	}
+
+	unicam_reg_write(dev, UNICAM_IBLS,
+			 dev->node[UNICAM_IMAGE_NODE].v_fmt.fmt.pix.bytesperline);
+	size = dev->node[UNICAM_IMAGE_NODE].v_fmt.fmt.pix.sizeimage;
+	unicam_wr_dma_addr(dev, addr[UNICAM_IMAGE_NODE], size, UNICAM_IMAGE_NODE);
+	unicam_set_packing_config(dev);
+	unicam_cfg_image_id(dev);
+
+	val = unicam_reg_read(dev, UNICAM_MISC);
+	unicam_set_field(&val, 1, UNICAM_FL0);
+	unicam_set_field(&val, 1, UNICAM_FL1);
+	unicam_reg_write(dev, UNICAM_MISC, val);
+
+	/* Enable peripheral */
+	unicam_reg_write_field(dev, UNICAM_CTRL, 1, UNICAM_CPE);
+
+	/* Load image pointers */
+	unicam_reg_write_field(dev, UNICAM_ICTL, 1, UNICAM_LIP_MASK);
+
+	/*
+	 * Enable trigger only for the first frame to
+	 * sync correctly to the FS from the source.
+	 */
+	unicam_reg_write_field(dev, UNICAM_ICTL, 1, UNICAM_TFC);
+}
+
+static void unicam_start_metadata(struct unicam_device *dev, dma_addr_t *addr)
+{
+	unsigned int size;
+
+	dev_dbg(dev->v4l2_dev.dev, "enable metadata dma\n");
+	size = dev->node[UNICAM_METADATA_NODE].v_fmt.fmt.meta.buffersize;
+	unicam_enable_ed(dev);
+	unicam_wr_dma_addr(dev, addr[UNICAM_METADATA_NODE], size, UNICAM_METADATA_NODE);
+	unicam_reg_write_field(dev, UNICAM_DCS, 1, UNICAM_LDP);
+}
+
+static void unicam_disable(struct unicam_device *dev)
+{
+	/* Analogue lane control disable */
+	unicam_reg_write_field(dev, UNICAM_ANA, 1, UNICAM_DDL);
+
+	/* Stop the output engine */
+	unicam_reg_write_field(dev, UNICAM_CTRL, 1, UNICAM_SOE);
+
+	/* Disable the data lanes. */
+	unicam_reg_write(dev, UNICAM_DAT0, 0);
+	unicam_reg_write(dev, UNICAM_DAT1, 0);
+
+	if (dev->max_data_lanes > 2) {
+		unicam_reg_write(dev, UNICAM_DAT2, 0);
+		unicam_reg_write(dev, UNICAM_DAT3, 0);
+	}
+
+	/* Peripheral reset */
+	unicam_reg_write_field(dev, UNICAM_CTRL, 1, UNICAM_CPR);
+	usleep_range(50, 100);
+	unicam_reg_write_field(dev, UNICAM_CTRL, 0, UNICAM_CPR);
+
+	/* Disable peripheral */
+	unicam_reg_write_field(dev, UNICAM_CTRL, 0, UNICAM_CPE);
+
+	/* Clear ED setup */
+	unicam_reg_write(dev, UNICAM_DCS, 0);
+
+	/* Disable all lane clocks */
+	unicam_clk_write(dev, 0);
+}
+
+/* -----------------------------------------------------------------------------
+ * V4L2 subdev Operations
+ */
+
+static int __unicam_subdev_set_routing(struct v4l2_subdev *sd,
+				       struct v4l2_subdev_state *state,
+				       struct v4l2_subdev_krouting *routing)
+{
+	int ret;
+
+	ret = v4l2_subdev_routing_validate_1_to_1(routing);
+	if (ret)
+		return ret;
+
+	v4l2_subdev_lock_state(state);
+
+	ret = v4l2_subdev_set_routing(sd, state, routing);

You've switched from v4l2_subdev_set_routing_with_fmt() to
v4l2_subdev_set_routing(), so this doesn't set formats anymore. It means
that .init_cfg() won't initialize formats. Was there an issue with
v4l2_subdev_set_routing_with_fmt() ?

+
+	v4l2_subdev_unlock_state(state);
+
+	if (ret)
+		return ret;
+
+	return 0;

You can replace those three lines with

	return ret;

+}
+
+static int unicam_subdev_set_routing(struct v4l2_subdev *sd,
+				     struct v4l2_subdev_state *state,
+				     enum v4l2_subdev_format_whence which,
+				     struct v4l2_subdev_krouting *routing)
+{
+	struct unicam_device *unicam = sd_to_unicam_device(sd);
+
+	if (which == V4L2_SUBDEV_FORMAT_ACTIVE && unicam->subdev.streaming)
+		return -EBUSY;
+
+	return __unicam_subdev_set_routing(sd, state, routing);
+}
+
+static int unicam_subdev_init_cfg(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_state *state)
+{
+	struct v4l2_subdev_route routes[] = {
+		{
+			.sink_pad = UNICAM_SD_PAD_SINK,
+			.sink_stream = 0,
+			.source_pad = UNICAM_SD_PAD_SOURCE_IMAGE,
+			.source_stream = 0,
+			.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
+		},
+	};
+
+	struct v4l2_subdev_krouting routing = {
+		.num_routes = ARRAY_SIZE(routes),
+		.routes = routes,
+	};
+
+	/* Initialize routing to single route to the fist source pad */
+	return __unicam_subdev_set_routing(sd, state, &routing);
+}
+
+static int unicam_subdev_enum_mbus_code(struct v4l2_subdev *sd,
+					struct v4l2_subdev_state *state,
+					struct v4l2_subdev_mbus_code_enum *code)
+{
+	int ret = 0;
+
+	v4l2_subdev_lock_state(state);
+
+	/* No transcoding, source and sink codes must match. */
+	if (unicam_sd_pad_is_source(code->pad)) {
+		struct v4l2_mbus_framefmt *fmt;
+
+		if (code->index > 0) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		fmt = v4l2_subdev_state_get_opposite_stream_format(state,
+								   code->pad,
+								   code->stream);
+		if (!fmt) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		code->code = fmt->code;
+	} else {
+		if (code->index >= ARRAY_SIZE(formats)) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		code->code = formats[code->index].code;

Shouldn't we restrict codes to image formats for the stream that goes to
the image pad, and to meta formats for the stream that goes to the meta
pad ? The following is an (untested) attempt to implement that.

	u32 pad, stream;
	int ret = -EINVAL;

	v4l2_subdev_lock_state(state);

	ret = v4l2_subdev_routing_find_opposite_end(&state->routing, code->pad,
						    code->stream, &pad,
						    &stream);
	if (ret)
		goto out;

	if (unicam_sd_pad_is_source(code->pad)) {
		/* No transcoding, source and sink codes must match. */
		struct v4l2_mbus_framefmt *fmt;

		fmt = v4l2_subdev_state_get_stream_format(state, pad, stream);
		if (!fmt)
			goto out;

		if (code->index > 0)
			goto out;

		code->code = fmt->code;
	} else {
		const struct unicam_fmt *formats;
		unsigned int num_formats;

		if (pad == UNICAM_SD_PAD_SOURCE_IMAGE) {
			formats = unicam_image_formats;
			num_formats = ARRAY_SIZE(unicam_image_formats);
		} else {
			formats = unicam_meta_formats;
			num_formats = ARRAY_SIZE(unicam_meta_formats);
		}

		if (code->index >= num_formats)
			goto out;

		code->code = formats[code->index].code;
	}

	ret = 0;

out:
	v4l2_subdev_unlock_state(state);

	return ret;

This requires splitting the formats array at the top of the driver into
two, for image and metadata formats. You may also need to update
unicam_subdev_enum_frame_size() accordingly.

+	}
+
+out:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+
+static int unicam_subdev_start_streaming(struct unicam_device *unicam, u32 pad,
+					 u32 stream)
+{
+	int ret;
+	struct media_pad *remote_pad;
+
+	unicam->sequence = 0;
+
+	dev_dbg(unicam->v4l2_dev.dev, "Running with %u data lanes\n",
+		unicam->active_data_lanes);
+
+	ret = clk_set_min_rate(unicam->vpu_clock, UNICAM_MIN_VPU_CLOCK_RATE);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "failed to set up VPU clock\n");
+		goto err_streaming;

You can return ret here, as you haven't set unicam->subdev.streaming to
true.

+	}
+
+	ret = clk_prepare_enable(unicam->vpu_clock);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Failed to enable VPU clock: %d\n", ret);
+		goto err_streaming;

Here you need to undo the clk_set_min_rate() call.

+	}
+
+	ret = clk_set_rate(unicam->clock, 100 * 1000 * 1000);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "failed to set up CSI clock\n");
+		goto err_vpu_clock;
+	}
+
+	ret = clk_prepare_enable(unicam->clock);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Failed to enable CSI clock: %d\n", ret);
+		goto err_vpu_clock;
+	}
+
+	remote_pad = media_entity_remote_pad(&unicam->subdev.pads[pad]);

Use unicam->remote_pad here.

+	ret = v4l2_subdev_call(unicam->sensor, video, enable_streams,
+			       remote_pad->index, BIT(stream));
+
+	if (ret && ret == -ENOIOCTLCMD)
+		ret = v4l2_subdev_call(unicam->sensor, video, s_stream, 1);
+
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "stream on failed in subdev\n");
+		return ret;

You need to disable clocks.

+	}
+
+	unicam->subdev.streaming = true;
+
+	return 0;
+
+err_vpu_clock:
+	if (clk_set_min_rate(unicam->vpu_clock, 0))
+		dev_err(unicam->v4l2_dev.dev, "failed to reset the VPU clock\n");
+	clk_disable_unprepare(unicam->vpu_clock);
+err_streaming:
+	unicam->subdev.streaming = false;
+
+	return ret;
+}
+
+static void unicam_subdev_stop_streaming(struct unicam_device *unicam, u32 pad,
+					 u32 stream)
+{
+	struct media_pad *remote_pad;
+	int ret;
+
+	remote_pad = media_entity_remote_pad(&unicam->subdev.pads[pad]);

Same here about remote_pad.

+	ret = v4l2_subdev_call(unicam->sensor, video, disable_streams,
+			       remote_pad->index, BIT(stream));
+
+	if (ret && ret == -ENOIOCTLCMD)
+		ret = v4l2_subdev_call(unicam->sensor, video, s_stream, 0);
+
+	clk_disable_unprepare(unicam->clock);
+	if (clk_set_min_rate(unicam->vpu_clock, 0))
+		dev_err(unicam->v4l2_dev.dev, "failed to reset the VPU clock\n");
+	clk_disable_unprepare(unicam->vpu_clock);
+
+	unicam->subdev.streaming = false;
+}
+
+static int unicam_sd_enable_streams(struct v4l2_subdev *sd, u32 pad,
+				    u64 streams_mask)
+{
+	struct unicam_device *unicam = sd_to_unicam_device(sd);
+	struct v4l2_subdev_state *state;
+	u32 other_pad, other_stream;
+	int ret;
+
+	if (WARN_ON(streams_mask != 1))
+		return -EINVAL;
+
+	state = v4l2_subdev_lock_active_state(sd);
+
+	ret = v4l2_subdev_routing_find_opposite_end(&state->routing, pad, 0,
+						    &other_pad, &other_stream);
+
+	v4l2_subdev_unlock_state(state);
+
+	if (ret)
+		return ret;
+
+	ret = unicam_subdev_start_streaming(unicam, other_pad, other_stream);

Any reason to split part of this in unicam_subdev_start_streaming() ?

+
+	return ret;
+}
+
+static int unicam_sd_disable_streams(struct v4l2_subdev *sd, u32 pad,
+				     u64 streams_mask)
+{
+	struct unicam_device *unicam = sd_to_unicam_device(sd);
+	struct v4l2_subdev_state *state;
+	u32 other_pad, other_stream;
+	int ret;
+
+	if (WARN_ON(streams_mask != 1))
+		return -EINVAL;
+
+	state = v4l2_subdev_lock_active_state(sd);
+
+	ret = v4l2_subdev_routing_find_opposite_end(&state->routing, pad, 0,
+						    &other_pad, &other_stream);
+
+	v4l2_subdev_unlock_state(state);
+
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "disable streams failed: %d\n", ret);
+		return ret;
+	}
+
+	unicam_subdev_stop_streaming(unicam, other_pad, other_stream);

Same question.

+
+	return 0;
+}
+
+static int unicam_subdev_set_pad_format(struct v4l2_subdev *sd,
+					struct v4l2_subdev_state *state,
+					struct v4l2_subdev_format *format)
+{
+	struct unicam_device *unicam = sd_to_unicam_device(sd);
+	struct v4l2_mbus_framefmt *sink_format, *source_format;
+	const struct unicam_fmt *fmtinfo;
+	unsigned int bpp;
+	int ret = 0;
+
+	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE && unicam->subdev.streaming) {
+		dev_err(unicam->v4l2_dev.dev, "format %d, subdev is %s\n",
+			format->which,
+			unicam->subdev.streaming ? "not streaming" : "streaming");

Drop this message, format->which and unicam->subdev.streaming always
have the same values here as you check them on the line before.

+		return -EBUSY;
+	}
+
+	/* No transcoding, source and sink formats must match. */
+	if (unicam_sd_pad_is_source(format->pad))
+		return v4l2_subdev_get_fmt(sd, state, format);
+
+	if (format->pad == UNICAM_SD_PAD_SOURCE_IMAGE) {

This can't happen as you return on the line above if format->pad is a
source.

+		fmtinfo = find_format_by_code(format->format.code);
+		if (!fmtinfo)
+			fmtinfo = &formats[0];
+
+		bpp = ALIGN(fmtinfo->depth, 8);

That's not right for packed formats.

+
+		format->format.width = clamp_t(unsigned int, format->format.width,
+					       UNICAM_MIN_WIDTH * 8 / bpp,
+					       UNICAM_MAX_WIDTH * 8 / bpp);

UNICAM_MIN_WIDTH and UNICAM_MAX_WIDTH are expressed in pixels already.

+		format->format.height = clamp_t(unsigned int, format->format.height,
+						UNICAM_MIN_HEIGHT,
+						UNICAM_MAX_HEIGHT);
+
+		format->format.code = fmtinfo->code;

This prevents picking an unpacked format.

+		format->format.field = V4L2_FIELD_NONE;
+	}
+
+	v4l2_subdev_lock_state(state);
+
+	sink_format = v4l2_state_get_stream_format(state, format->pad,
+						   format->stream);
+	source_format = v4l2_subdev_state_get_opposite_stream_format(state,
+								     format->pad,
+								     format->stream);
+	if (!sink_format || !source_format) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	*sink_format = format->format;
+	*source_format = format->format;
+out:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+
+static int unicam_subdev_enum_frame_size(struct v4l2_subdev *sd,
+					 struct v4l2_subdev_state *state,
+					 struct v4l2_subdev_frame_size_enum *fse)
+{
+	const struct unicam_fmt *fmtinfo;
+	int ret = 0;
+
+	if (fse->index > 0)
+		return -EINVAL;
+
+	v4l2_subdev_lock_state(state);
+
+	/* No transcoding, source and sink formats must match. */
+	if (unicam_sd_pad_is_source(fse->pad)) {
+		struct v4l2_mbus_framefmt *fmt;
+
+		fmt = v4l2_subdev_state_get_opposite_stream_format(state,
+								   fse->pad,
+								   fse->stream);
+		if (!fmt) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (fse->code != fmt->code) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		fse->min_width = fmt->width;
+		fse->max_width = fmt->width;
+		fse->min_height = fmt->height;
+		fse->max_height = fmt->height;
+	} else {
+		fmtinfo = find_format_by_code(fse->code);
+		if (!fmtinfo) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		fse->min_width = UNICAM_MIN_WIDTH * 8 / ALIGN(fmtinfo->depth, 8);
+		fse->max_width = UNICAM_MAX_WIDTH * 8 / ALIGN(fmtinfo->depth, 8);

UNICAM_MIN_WIDTH and UNICAM_MAX_WIDTH are expressed in pixels already.

+		fse->min_height = UNICAM_MIN_HEIGHT;
+		fse->max_height = UNICAM_MAX_HEIGHT;
+	}
+
+out:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+
+static const struct v4l2_subdev_video_ops unicam_subdev_video_ops = {
+	.enable_streams	= unicam_sd_enable_streams,
+	.disable_streams = unicam_sd_disable_streams,
+};
+
+static const struct v4l2_subdev_pad_ops unicam_subdev_pad_ops = {
+	.init_cfg		= unicam_subdev_init_cfg,
+	.enum_mbus_code		= unicam_subdev_enum_mbus_code,
+	.get_fmt		= v4l2_subdev_get_fmt,
+	.set_fmt		= unicam_subdev_set_pad_format,
+	.set_routing		= unicam_subdev_set_routing,
+	.enum_frame_size	= unicam_subdev_enum_frame_size,
+};
+
+static const struct v4l2_subdev_ops unicam_subdev_ops = {
+	.video		= &unicam_subdev_video_ops,
+	.pad		= &unicam_subdev_pad_ops,
+};
+
+static const struct media_entity_operations unicam_subdev_media_ops = {
+	.link_validate = v4l2_subdev_link_validate,
+	.has_route = v4l2_subdev_has_route,
+};
+
+/* -----------------------------------------------------------------------------
+ * Videobuf2 Queue Operations
+ */
+
+static int unicam_queue_setup(struct vb2_queue *vq,
+			      unsigned int *nbuffers,
+			      unsigned int *nplanes,
+			      unsigned int sizes[],
+			      struct device *alloc_devs[])
+{
+	struct unicam_node *node = vb2_get_drv_priv(vq);
+	struct unicam_device *dev = node->dev;
+	unsigned int size = is_image_node(node) ?
+				node->v_fmt.fmt.pix.sizeimage :
+				node->v_fmt.fmt.meta.buffersize;
+
+	if (vq->num_buffers + *nbuffers < 3)
+		*nbuffers = 3 - vq->num_buffers;
+
+	if (*nplanes) {
+		if (sizes[0] < size) {
+			dev_dbg(dev->v4l2_dev.dev, "sizes[0] %i < size %u\n", sizes[0],
+				size);
+			return -EINVAL;
+		}
+		size = sizes[0];
+	}
+
+	*nplanes = 1;
+	sizes[0] = size;
+
+	return 0;
+}
+
+static int unicam_buffer_prepare(struct vb2_buffer *vb)
+{
+	struct unicam_node *node = vb2_get_drv_priv(vb->vb2_queue);
+	struct unicam_device *dev = node->dev;
+	struct unicam_buffer *buf = to_unicam_buffer(vb);
+	unsigned long size;
+
+	if (WARN_ON(!node->fmt))
+		return -EINVAL;
+
+	size = is_image_node(node) ? node->v_fmt.fmt.pix.sizeimage :
+				     node->v_fmt.fmt.meta.buffersize;
+	if (vb2_plane_size(vb, 0) < size) {
+		dev_dbg(dev->v4l2_dev.dev, "data will not fit into plane (%lu < %lu)\n",
+			vb2_plane_size(vb, 0), size);
+		return -EINVAL;
+	}
+
+	vb2_set_plane_payload(&buf->vb.vb2_buf, 0, size);
+	return 0;
+}
+
+static void unicam_buffer_queue(struct vb2_buffer *vb)
+{
+	struct unicam_node *node = vb2_get_drv_priv(vb->vb2_queue);
+	struct unicam_buffer *buf = to_unicam_buffer(vb);
+
+	spin_lock_irq(&node->dma_queue_lock);
+	list_add_tail(&buf->list, &node->dma_queue);
+	spin_unlock_irq(&node->dma_queue_lock);
+}
+
+static void unicam_return_buffers(struct unicam_node *node,
+				  enum vb2_buffer_state state)
+{
+	struct unicam_buffer *buf, *tmp;
+
+	list_for_each_entry_safe(buf, tmp, &node->dma_queue, list) {
+		list_del(&buf->list);
+		vb2_buffer_done(&buf->vb.vb2_buf, state);
+	}
+
+	if (node->cur_frm)
+		vb2_buffer_done(&node->cur_frm->vb.vb2_buf,
+				state);
+	if (node->next_frm && node->cur_frm != node->next_frm)
+		vb2_buffer_done(&node->next_frm->vb.vb2_buf,
+				state);
+
+	node->cur_frm = NULL;
+	node->next_frm = NULL;
+}
+
+static int unicam_video_check_format(struct unicam_node *node)
+{
+	const struct v4l2_mbus_framefmt *format;
+	struct unicam_device *dev = node->dev;
+	struct v4l2_subdev_state *state;
+	int ret = 0;
+
+	state = v4l2_subdev_lock_active_state(&dev->subdev.sd);
+
+	format = v4l2_state_get_stream_format(state, dev->remote_pad->index, 0);

You can replace dev->remote_pad->index with UNICAM_SD_PAD_SOURCE_IMAGE.

+	if (!format) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (node->fmt->code != format->code ||
+	    node->v_fmt.fmt.pix.height != format->height ||
+	    node->v_fmt.fmt.pix.width != format->width ||
+	    node->v_fmt.fmt.pix.field != format->field) {
+		dev_dbg(dev->v4l2_dev.dev, "(%d x %d) %08X %s != (%d x %d) %08X %s\n",

%u for unsigned, and %08x instead of %08X.

+			node->v_fmt.fmt.pix.width, node->v_fmt.fmt.pix.height,
+			node->fmt->code,
+			v4l2_field_names[node->v_fmt.fmt.pix.field],
+			format->width, format->height, format->code,
+			v4l2_field_names[format->field]);
+		ret = -EPIPE;
+		goto out;
+	}
+
+out:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+
+static int unicam_start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	struct unicam_node *node = vb2_get_drv_priv(vq);
+	struct unicam_device *dev = node->dev;
+	dma_addr_t buffer_addr[UNICAM_MAX_NODES] = { 0 };
+	struct unicam_buffer *buf;
+	struct media_pad *remote_pad;
+	struct v4l2_subdev_route *route = NULL;
+	struct v4l2_subdev_route *r;
+	struct v4l2_subdev_state *state;
+	unsigned long flags;
+	unsigned int i;
+	int ret;
+
+	/* Get remote pad */
+	remote_pad = media_entity_remote_pad(&node->pad);
+	if (!remote_pad) {
+		dev_err(dev->v4l2_dev.dev, "Context not connected\n");
+		ret = -ENODEV;
+		goto err_streaming;
+	}

This can't happen. Use UNICAM_SD_PAD_SOURCE_IMAGE or
UNICAM_SD_PAD_SOURCE_METADATA instead of going through
media_entity_remote_pad(). Same when stopping streaming.

+
+	/* Look for the route for the given pad and stream. */
+	state = v4l2_subdev_lock_active_state(&dev->subdev.sd);
+
+	/* Find the stream */
+	for_each_active_route(&state->routing, r) {
+		if (r->source_pad != remote_pad->index)
+			continue;
+
+		route = r;
+
+		break;
+	}

Can you use v4l2_subdev_routing_find_opposite_end() ?

+
+	if (!route) {
+		v4l2_subdev_unlock_state(state);
+		dev_err(dev->v4l2_dev.dev, "Failed to find route\n");
+		ret = -ENODEV;
+		goto err_streaming;
+	}
+
+	/* Store the PHY connected to this video device. */

The PHY ?

+	node->stream = route->sink_stream;
+	dev_dbg(dev->v4l2_dev.dev, "Starting stream %u on pad %d on subdev %s\n",
+		node->stream, remote_pad->index, dev->subdev.sd.name);
+	v4l2_subdev_unlock_state(state);
+
+	/* The metadata node can't be started alone. */
+	if (node == &dev->node[UNICAM_METADATA_NODE]) {

	if (is_metadata_node(node)) {

+		if (!dev->node[UNICAM_IMAGE_NODE].streaming) {
+			dev_err(dev->v4l2_dev.dev,
+				"Can't start metadata without image\n");
+			return -EINVAL;
+		}
+		dev_dbg(dev->v4l2_dev.dev, "starting metadata node\n");
+
+		spin_lock_irqsave(&node->dma_queue_lock, flags);
+		buf = list_first_entry(&node->dma_queue,
+				       struct unicam_buffer, list);
+		dev_dbg(dev->v4l2_dev.dev, "buffer %d: %p\n", i, buf);
+		node->cur_frm = buf;
+		node->next_frm = buf;
+		list_del(&buf->list);
+		spin_unlock_irqrestore(&node->dma_queue_lock, flags);
+
+		buffer_addr[UNICAM_METADATA_NODE] =
+			vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
+		dev_dbg(dev->v4l2_dev.dev, "buffer %d addr: %lld\n", i, buffer_addr[i]);
+
+		unicam_start_metadata(dev, buffer_addr);
+		node->streaming = true;
+		return 0;
+	}
+
+	ret = pm_runtime_get_sync(dev->pdev);
+	if (ret < 0) {
+		dev_err(dev->v4l2_dev.dev, "pm_runtime_get_sync failed\n");
+		goto err_streaming;
+	}
+
+	ret = media_pipeline_start(node->video_dev.entity.pads, &node->pipe);
+	if (ret < 0) {
+		dev_dbg(dev->v4l2_dev.dev, "Failed to start media pipeline: %d\n", ret);
+		goto err_pm_put;
+	}
+
+	ret = unicam_video_check_format(node);
+	if (ret < 0) {
+		dev_err(dev->v4l2_dev.dev, "Video format is incorrect: %d\n", ret);
+		goto error_pipeline;
+	}
+
+	dev_dbg(dev->v4l2_dev.dev, "node %s\n", node->video_dev.name);
+
+	spin_lock_irqsave(&node->dma_queue_lock, flags);
+	buf = list_first_entry(&node->dma_queue,
+			       struct unicam_buffer, list);
+	dev_dbg(dev->v4l2_dev.dev, "buffer %d: %p\n", i, buf);
+	node->cur_frm = buf;
+	node->next_frm = buf;
+	list_del(&buf->list);
+	spin_unlock_irqrestore(&node->dma_queue_lock, flags);
+
+	buffer_addr[UNICAM_IMAGE_NODE] =
+			vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
+
+	dev_dbg(dev->v4l2_dev.dev, "Start unicam\n");
+	unicam_start_rx(dev, buffer_addr);
+
+	dev_dbg(dev->v4l2_dev.dev, "Enable stream\n");
+	ret = v4l2_subdev_call(&dev->subdev.sd, video, enable_streams,
+			       remote_pad->index, BIT(node->stream));

node->stream is the sink stream, while remote_pad->index is a source
pad. You're mixing concepts, please go through the code and double-check
that all pads and streams are correct.

+	if (ret < 0) {
+		dev_err(dev->v4l2_dev.dev, "stream on failed in subdev\n");
+		goto error_pipeline;
+	}
+
+	node->streaming = true;
+
+	return 0;
+
+error_pipeline:
+	media_pipeline_stop(node->video_dev.entity.pads);
+err_pm_put:
+	pm_runtime_put_sync(dev->pdev);
+err_streaming:
+	return ret;
+}
+
+static void unicam_stop_streaming(struct vb2_queue *vq)
+{
+	struct unicam_node *node = vb2_get_drv_priv(vq);
+	struct unicam_device *dev = node->dev;
+	struct media_pad *remote_pad;
+
+	node->streaming = false;
+
+	remote_pad = media_entity_remote_pad(&node->pad);
+	v4l2_subdev_call(&dev->subdev.sd, video, disable_streams,
+			 remote_pad->index, BIT(node->stream));
+
+	/* We can stream only with the image node. */
+	if (is_metadata_node(node)) {
+		/*
+		 * Allow the hardware to spin in the dummy buffer.
+		 * This is only really needed if the embedded data pad is
+		 * disabled before the image pad.
+		 */
+		unicam_wr_dma_addr(dev, node->dummy_buf_dma_addr,
+				   UNICAM_DUMMY_BUF_SIZE, UNICAM_METADATA_NODE);
+		goto dequeue_buffers;
+	}
+
+	unicam_disable(dev);
+
+	media_pipeline_stop(node->video_dev.entity.pads);
+	pm_runtime_put_sync(dev->pdev);

You can drop the _sync.

+
+dequeue_buffers:
+	/* Clear all queued buffers for the node */
+	unicam_return_buffers(node, VB2_BUF_STATE_ERROR);
+}
+
+static const struct vb2_ops unicam_video_qops = {
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
+	.queue_setup		= unicam_queue_setup,
+	.buf_prepare		= unicam_buffer_prepare,
+	.buf_queue		= unicam_buffer_queue,
+	.start_streaming	= unicam_start_streaming,
+	.stop_streaming		= unicam_stop_streaming,
+};
+
+/* -----------------------------------------------------------------------------
+ *  V4L2 video device Operations
+ */
+
+static int unicam_querycap(struct file *file, void *priv,
+			   struct v4l2_capability *cap)
+{
+	struct unicam_node *node = video_drvdata(file);
+	struct unicam_device *dev = node->dev;
+
+	strscpy(cap->driver, UNICAM_MODULE_NAME, sizeof(cap->driver));
+	strscpy(cap->card, UNICAM_MODULE_NAME, sizeof(cap->card));
+
+	snprintf(cap->bus_info, sizeof(cap->bus_info),
+		 "platform:%s", dev_name(dev->pdev));
+
+	cap->capabilities |= V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_META_CAPTURE;
+
+	return 0;
+}
+
+static int unicam_log_status(struct file *file, void *fh)
+{
+	struct unicam_node *node = video_drvdata(file);
+	struct unicam_device *dev = node->dev;
+	u32 reg;
+
+	/* status for sub devices */
+	v4l2_device_call_all(&dev->v4l2_dev, 0, core, log_status);
+
+	dev_info(dev->v4l2_dev.dev, "-----Receiver status-----\n");
+	dev_info(dev->v4l2_dev.dev, "V4L2 width/height:   %ux%u\n",
+		 node->v_fmt.fmt.pix.width, node->v_fmt.fmt.pix.height);
+	dev_info(dev->v4l2_dev.dev, "Mediabus format:     %08x\n", node->fmt->code);
+	dev_info(dev->v4l2_dev.dev, "V4L2 format:         %08x\n",
+		 node->v_fmt.fmt.pix.pixelformat);
+	reg = unicam_reg_read(dev, UNICAM_IPIPE);
+	dev_info(dev->v4l2_dev.dev, "Unpacking/packing:   %u / %u\n",
+		 unicam_get_field(reg, UNICAM_PUM_MASK),
+		 unicam_get_field(reg, UNICAM_PPM_MASK));
+	dev_info(dev->v4l2_dev.dev, "----Live data----\n");
+	dev_info(dev->v4l2_dev.dev, "Programmed stride:   %4u\n",
+		 unicam_reg_read(dev, UNICAM_IBLS));
+	dev_info(dev->v4l2_dev.dev, "Detected resolution: %ux%u\n",
+		 unicam_reg_read(dev, UNICAM_IHSTA),
+		 unicam_reg_read(dev, UNICAM_IVSTA));
+	dev_info(dev->v4l2_dev.dev, "Write pointer:       %08x\n",
+		 unicam_reg_read(dev, UNICAM_IBWP));
+
+	return 0;
+}
+
+static int unicam_subscribe_event(struct v4l2_fh *fh,
+				  const struct v4l2_event_subscription *sub)
+{
+	switch (sub->type) {
+	case V4L2_EVENT_FRAME_SYNC:
+		return v4l2_event_subscribe(fh, sub, 2, NULL);
+	}
+
+	return v4l2_ctrl_subscribe_event(fh, sub);
+}
+
+static int unicam_enum_fmt_vid_cap(struct file *file, void  *priv,
+				   struct v4l2_fmtdesc *f)
+{
+	unsigned int i, index;
+
+	for (i = 0, index = 0; i < ARRAY_SIZE(formats); i++) {
+		if (f->mbus_code && formats[i].code != f->mbus_code)
+			continue;
+		if (formats[i].metadata_fmt)
+			continue;
+
+		if (index == f->index) {
+			f->pixelformat = formats[i].fourcc;
+			return 0;
+		}
+
+		index++;
+
+		if (formats[i].unpacked_fourcc) {
+			if (index == f->index) {
+				f->pixelformat = formats[i].unpacked_fourcc;
+				return 0;
+			}
+			index++;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int unicam_g_fmt_vid_cap(struct file *file, void *priv,
+				struct v4l2_format *f)
+{
+	struct unicam_node *node = video_drvdata(file);
+
+	*f = node->v_fmt;
+
+	return 0;
+}
+
+static const struct unicam_fmt *
+unicam_try_fmt(struct unicam_node *node, struct v4l2_format *f)
+{
+	struct v4l2_pix_format *v4l2_format = &f->fmt.pix;
+	struct unicam_device *dev = node->dev;
+	const struct unicam_fmt *fmt;
+
+	/*
+	 * Default to the first format if the requested pixel format code isn't
+	 * supported.
+	 */
+	fmt = find_format_by_fourcc(v4l2_format->pixelformat);
+	if (!fmt) {
+		fmt = &formats[0];
+		v4l2_format->pixelformat = fmt->fourcc;
+	}
+
+	unicam_calc_format_size_bpl(dev, fmt, f);
+
+	if (v4l2_format->field == V4L2_FIELD_ANY)
+		v4l2_format->field = V4L2_FIELD_NONE;
+
+	dev_dbg(dev->v4l2_dev.dev, "%s: %08x %ux%u (bytesperline %u sizeimage %u)\n",
+		__func__, v4l2_format->pixelformat,
+		v4l2_format->width, v4l2_format->height,
+		v4l2_format->bytesperline, v4l2_format->sizeimage);
+
+	return fmt;
+}
+
+static int unicam_try_fmt_vid_cap(struct file *file, void *priv,
+				  struct v4l2_format *f)
+{
+	struct unicam_node *node = video_drvdata(file);
+
+	unicam_try_fmt(node, f);
+	return 0;
+}
+
+static int unicam_s_fmt_vid_cap(struct file *file, void *priv,
+				struct v4l2_format *f)
+{
+	struct unicam_node *node = video_drvdata(file);
+	struct unicam_device *dev = node->dev;
+	const struct unicam_fmt *fmt;
+
+	if (vb2_is_busy(&node->buffer_queue)) {
+		dev_dbg(dev->v4l2_dev.dev, "%s device busy\n", __func__);
+		return -EBUSY;
+	}
+
+	fmt = unicam_try_fmt(node, f);

	node->fmt = fmt;

+
+	node->v_fmt = *f;
+	node->fmt = fmt;
+
+	return 0;
+}
+
+static int unicam_enum_framesizes(struct file *file, void *fh,
+				  struct v4l2_frmsizeenum *fsize)
+{
+	if (fsize->index > 0)
+		return -EINVAL;
+
+	if (!find_format_by_fourcc(fsize->pixel_format))
+		return -EINVAL;
+
+	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
+	fsize->stepwise.min_width = UNICAM_MIN_WIDTH;
+	fsize->stepwise.max_width = UNICAM_MAX_WIDTH;
+	fsize->stepwise.step_width = 1;
+	fsize->stepwise.min_height = UNICAM_MIN_HEIGHT;
+	fsize->stepwise.max_height = UNICAM_MAX_HEIGHT;
+	fsize->stepwise.step_height = 1;
+
+	return 0;
+}
+
+static int unicam_enum_fmt_meta_cap(struct file *file, void  *priv,

Extra space after void.

+				    struct v4l2_fmtdesc *f)
+{
+	unsigned int i, index;
+
+	for (i = 0, index = 0; i < ARRAY_SIZE(formats); i++) {
+		if (f->mbus_code && formats[i].code != f->mbus_code)
+			continue;
+		if (!formats[i].metadata_fmt)
+			continue;
+
+		if (index == f->index) {
+			f->pixelformat = formats[i].fourcc;
+			f->type = V4L2_BUF_TYPE_META_CAPTURE;
+			return 0;
+		}
+		index++;
+	}
+
+	return -EINVAL;
+}
+
+static int unicam_g_fmt_meta_cap(struct file *file, void *priv,
+				 struct v4l2_format *f)
+{
+	struct unicam_node *node = video_drvdata(file);
+	struct v4l2_meta_format *meta = &f->fmt.meta;
+
+	meta->dataformat = node->v_fmt.fmt.meta.dataformat;
+	meta->buffersize = node->v_fmt.fmt.meta.buffersize;

How about just

	f->fmt.meta = node->v_fmt.fmt.meta;

?

+
+	return 0;
+}
+
+static int unicam_try_fmt_meta_cap(struct file *file, void *priv,
+				   struct v4l2_format *f)
+{
+	f->fmt.meta.dataformat = V4L2_META_FMT_8;

Should we do something with buffersize too ? At least clamp it to
reasonable min/max values ?

+
+	return 0;
+}
+
+static int unicam_s_fmt_meta_cap(struct file *file, void *priv,
+				 struct v4l2_format *f)
+{
+	struct unicam_node *node = video_drvdata(file);
+
+	unicam_try_fmt_meta_cap(file, priv, f);
+
+	node->v_fmt = *f;
+
+	return 0;
+}
+
+static const struct v4l2_ioctl_ops unicam_ioctl_ops = {
+	.vidioc_querycap      = unicam_querycap,
+	.vidioc_enum_fmt_vid_cap  = unicam_enum_fmt_vid_cap,
+	.vidioc_g_fmt_vid_cap     = unicam_g_fmt_vid_cap,
+	.vidioc_try_fmt_vid_cap   = unicam_try_fmt_vid_cap,
+	.vidioc_s_fmt_vid_cap     = unicam_s_fmt_vid_cap,
+
+	.vidioc_enum_fmt_meta_cap	= unicam_enum_fmt_meta_cap,
+	.vidioc_g_fmt_meta_cap		= unicam_g_fmt_meta_cap,
+	.vidioc_try_fmt_meta_cap	= unicam_try_fmt_meta_cap,
+	.vidioc_s_fmt_meta_cap		= unicam_s_fmt_meta_cap,

I think you can drop the _cap suffix from the function names, as this
driver only supports capture, not output.

+
+	.vidioc_enum_framesizes   = unicam_enum_framesizes,
+	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
+	.vidioc_create_bufs   = vb2_ioctl_create_bufs,
+	.vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
+	.vidioc_querybuf      = vb2_ioctl_querybuf,
+	.vidioc_qbuf          = vb2_ioctl_qbuf,
+	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
+	.vidioc_expbuf        = vb2_ioctl_expbuf,
+	.vidioc_streamon      = vb2_ioctl_streamon,
+	.vidioc_streamoff     = vb2_ioctl_streamoff,
+
+	.vidioc_log_status		= unicam_log_status,
+	.vidioc_subscribe_event		= unicam_subscribe_event,
+	.vidioc_unsubscribe_event	= v4l2_event_unsubscribe,
+};
+
+/* unicam capture driver file operations */
+static const struct v4l2_file_operations unicam_fops = {
+	.owner		= THIS_MODULE,
+	.open           = v4l2_fh_open,
+	.release        = vb2_fop_release,
+	.poll		= vb2_fop_poll,
+	.unlocked_ioctl = video_ioctl2,
+	.mmap           = vb2_fop_mmap,
+};

/* -----------------------------------------------------------------------------
 * V4L2 async notifier
 */

+
+static int
+unicam_async_bound(struct v4l2_async_notifier *notifier,
+		   struct v4l2_subdev *subdev,
+		   struct v4l2_async_subdev *asd)
+{
+	struct unicam_device *unicam = v4l2_device_to_unicam_device(notifier->v4l2_dev);
+	struct media_pad *sink = &unicam->subdev.sd.entity.pads[UNICAM_SD_PAD_SINK];
+
+	unicam->sensor = subdev;
+	dev_dbg(unicam->v4l2_dev.dev, "Using sensor %s for capture\n",
+		subdev->name);
+
+	return v4l2_create_fwnode_links_to_pad(subdev, sink, MEDIA_LNK_FL_ENABLED |
+					       MEDIA_LNK_FL_IMMUTABLE);
+}
+
+static void unicam_release(struct kref *kref)
+{
+	struct unicam_device *unicam =
+		container_of(kref, struct unicam_device, kref);
+
+	media_device_cleanup(&unicam->mdev);

You need to make this conditional, otherwise there are code paths where
this function will be called without media_device_init() called first.

	if (unicam->mdev.dev)
		media_device_cleanup(&unicam->mdev);

should do.

+
+	kfree(unicam);
+}
+
+static void unicam_put(struct unicam_device *unicam)
+{
+	kref_put(&unicam->kref, unicam_release);
+}
+
+static struct unicam_device *unicam_get(struct unicam_device *unicam)
+{
+	kref_get(&unicam->kref);
+	return unicam;
+}

I'd move those three functions much further up, just before the misc
helpers.

+
+static void unicam_node_release(struct video_device *vdev)
+{
+	struct unicam_node *node = video_get_drvdata(vdev);
+
+	unicam_put(node->dev);
+}
+
+static void unicam_set_default_format(struct unicam_node *node)
+{
+	static const struct v4l2_mbus_framefmt format = {
+		.width = 640,
+		.height = 480,
+		.code = MEDIA_BUS_FMT_UYVY8_1X16,
+		.field = V4L2_FIELD_NONE,
+		.colorspace = V4L2_COLORSPACE_SRGB,
+		.ycbcr_enc = V4L2_YCBCR_ENC_601,
+		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
+		.xfer_func = V4L2_XFER_FUNC_SRGB,
+		.flags = 0,
+	};

Move this out of the function to a global variable, and use it to
initialize the subdev formats too in __unicam_subdev_set_routing().

+
+	if (is_image_node(node)) {
+		struct v4l2_pix_format *pix_fmt = &node->v_fmt.fmt.pix;
+
+		pix_fmt->width = format.width;
+		pix_fmt->height = format.height;
+		pix_fmt->field = format.field;
+		pix_fmt->colorspace = format.colorspace;
+		pix_fmt->ycbcr_enc = format.ycbcr_enc;
+		pix_fmt->quantization = format.quantization;
+		pix_fmt->xfer_func = format.xfer_func;
+		pix_fmt->pixelformat = formats[0].fourcc;
+		unicam_calc_format_size_bpl(node->dev, &formats[0],
+					    &node->v_fmt);
+		node->v_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+		node->fmt = &formats[0];
+	} else {
+		const struct unicam_fmt *fmt;
+
+		/* Fix this node format as embedded data. */
+		fmt = find_format_by_code(MEDIA_BUS_FMT_METADATA_8);
+		node->fmt = fmt;
+		node->v_fmt.fmt.meta.dataformat = fmt->fourcc;
+		node->v_fmt.fmt.meta.buffersize = UNICAM_EMBEDDED_SIZE;
+		node->v_fmt.type = V4L2_BUF_TYPE_META_CAPTURE;
+	}
+}
+
+static int register_node(struct unicam_device *unicam,

Prefix.

+			 enum unicam_node_type type)
+{
+	struct video_device *vdev;
+	struct vb2_queue *q;
+	struct unicam_node *node = &unicam->node[type];
+	int ret;
+
+	node->dev = unicam_get(unicam);
+	node->node_id = type;
+
+	spin_lock_init(&node->dma_queue_lock);
+	mutex_init(&node->lock);
+
+	/* Initialize the videobuf2 queue. */
+	INIT_LIST_HEAD(&node->dma_queue);

This line should go above, it's not the videobuf2 queue.

+
+	q = &node->buffer_queue;
+	q->type = type == UNICAM_IMAGE_NODE ? V4L2_BUF_TYPE_VIDEO_CAPTURE
+					    : V4L2_BUF_TYPE_META_CAPTURE;
+	q->io_modes = VB2_MMAP | VB2_DMABUF;
+	q->drv_priv = node;
+	q->ops = &unicam_video_qops;
+	q->mem_ops = &vb2_dma_contig_memops;
+	q->buf_struct_size = sizeof(struct unicam_buffer);
+	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->lock = &node->lock;
+	q->min_buffers_needed = 1;
+	q->dev = unicam->pdev;
+
+	ret = vb2_queue_init(q);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "vb2_queue_init() failed\n");
+		goto err_unicam_put;
+	}
+
+	/* Initialize the video device. */
+	vdev = &node->video_dev;
+	vdev->release = unicam_node_release;
+	vdev->fops = &unicam_fops;
+	vdev->ioctl_ops = &unicam_ioctl_ops;
+	vdev->v4l2_dev = &unicam->v4l2_dev;
+	vdev->vfl_dir = VFL_DIR_RX;
+	vdev->queue = q;
+	vdev->lock = &node->lock;
+	vdev->device_caps = (type == UNICAM_IMAGE_NODE) ?

No need for parentheses.

+			     V4L2_CAP_VIDEO_CAPTURE : V4L2_CAP_META_CAPTURE;
+	vdev->device_caps |= V4L2_CAP_STREAMING | V4L2_CAP_IO_MC;
+
+	/* Define the device names */
+	snprintf(vdev->name, sizeof(vdev->name), "%s-%s", UNICAM_MODULE_NAME,
+		 type == UNICAM_IMAGE_NODE ? "image" : "embedded");
+
+	video_set_drvdata(vdev, node);
+	if (type == UNICAM_IMAGE_NODE)
+		vdev->entity.flags |= MEDIA_ENT_FL_DEFAULT;
+	node->pad.flags = MEDIA_PAD_FL_SINK;
+	ret = media_entity_pads_init(&vdev->entity, 1, &node->pad);
+	if (ret)
+		goto err_unicam_put;
+
+	node->dummy_buf_cpu_addr = dma_alloc_coherent(unicam->pdev,
+						      UNICAM_DUMMY_BUF_SIZE,
+						      &node->dummy_buf_dma_addr,
+						      GFP_KERNEL);
+	if (!node->dummy_buf_cpu_addr) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to allocate dummy buffer.\n");
+		ret = -ENOMEM;
+		goto err_entity_cleanup;
+	}
+
+	unicam_set_default_format(node);
+
+	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to register video device %s\n",
+			vdev->name);
+		goto err_dma_free;
+	}
+
+	node->registered = true;
+
+	ret = media_create_pad_link(&unicam->subdev.sd.entity,
+				    node->src_pad_id,
+				    &node->video_dev.entity,
+				    0,
+				    MEDIA_LNK_FL_ENABLED |
+				    MEDIA_LNK_FL_IMMUTABLE);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to create pad link for %s",
+			unicam->sensor->name);
+		goto err_unregister_device;
+	}
+
+	return 0;
+
+err_unregister_device:
+	video_unregister_device(&node->video_dev);

Now that the video device has been registered, video_unregister_device()
will end up calling unicam_put() through unicam_node_release(). The
unicam_put() call below will thus release the reference a second time.

As the caller of this function calls unregister_nodes() on error, you
can drop video_unregister_device() here and simply return an error
directly if media_create_pad_link() fails. Adding a comment there will
be useful too:

	ret = media_create_pad_link(&unicam->subdev.sd.entity,
				    node->src_pad_id,
				    &node->video_dev.entity, 0,
				    MEDIA_LNK_FL_ENABLED |
				    MEDIA_LNK_FL_IMMUTABLE);
	if (ret) {
		/*
		 * No need for cleanup, the caller will unregister the
		 * video device, which will drop the reference on the
		 * device and trigger the cleanup.
		 */
		return ret;
	}

+err_dma_free:
+	dma_free_coherent(unicam->pdev, UNICAM_DUMMY_BUF_SIZE,
+			  node->dummy_buf_cpu_addr,
+			  node->dummy_buf_dma_addr);
+err_entity_cleanup:
+	media_entity_cleanup(&vdev->entity);
+err_unicam_put:
+	unicam_put(unicam);
+	return ret;
+}
+
+static void unregister_nodes(struct unicam_device *unicam)

Prefix.

+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
+		struct unicam_node *node = &unicam->node[i];
+
+		if (node->dummy_buf_cpu_addr)
+			dma_free_coherent(unicam->pdev, UNICAM_DUMMY_BUF_SIZE,
+					  node->dummy_buf_cpu_addr,
+					  node->dummy_buf_dma_addr);
+
+		if (node->registered) {
+			video_unregister_device(&node->video_dev);
+			node->registered = false;
+		}
+	}
+}

Let's move this and the previous function just after unicam_fops.

+
+static int unicam_async_complete(struct v4l2_async_notifier *notifier)
+{
+	struct unicam_device *unicam = v4l2_device_to_unicam_device(notifier->v4l2_dev);
+	unsigned int i, source_pads = 0;
+	int ret;
+
+	for (i = 0; i < unicam->subdev.sd.entity.num_pads; i++) {
+		if (unicam->subdev.sd.entity.pads[i].flags & MEDIA_PAD_FL_SOURCE) {
+			if (source_pads < UNICAM_MAX_NODES) {
+				unicam->node[source_pads].src_pad_id = i;
+				dev_dbg(unicam->v4l2_dev.dev, "source pad %u is index %u\n",
+					source_pads, i);
+			}
+			source_pads++;
+		}
+	}
+	if (!source_pads) {
+		dev_err(unicam->v4l2_dev.dev, "No source pads on subdev.\n");
+		goto unregister;
+	}

Please re-read the review of v2. This whole block should be dropped, and
the src_pad_id field be dropped from unicam_node.

+
+	ret = register_node(unicam, UNICAM_IMAGE_NODE);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to register image video device.\n");
+		goto unregister;
+	}
+
+	/* \todo: The sensor should report it. */
+	unicam->sensor_embedded_data = true;

Not used.

+
+	ret = register_node(unicam, UNICAM_METADATA_NODE);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to register metadata video device.\n");
+		goto unregister;
+	}
+
+	ret = v4l2_device_register_subdev_nodes(&unicam->v4l2_dev);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Unable to register subdev nodes.\n");
+		goto unregister;
+	}
+
+	unicam->remote_pad = media_entity_remote_pad(&unicam->node[UNICAM_IMAGE_NODE].pad);

Store the pointer to the sensor's source pad instead, and move this to
unicam_async_bound() when set set unicam->sensor.

+	if (!unicam->remote_pad)
+		return -ENODEV;
+
+	return 0;
+
+unregister:
+	unregister_nodes(unicam);
+	unicam_put(unicam);
+
+	return ret;
+}
+
+static const struct v4l2_async_notifier_operations unicam_async_ops = {
+	.bound = unicam_async_bound,
+	.complete = unicam_async_complete,
+};
+
+static int of_unicam_connect_subdevs(struct unicam_device *dev)

unicam_connect_of_subdevs() to use the unicam_ prefix consistently.

+{
+	struct device *pdev = dev->pdev;

You can drop this variable and use dev->pdev in the two locations where
this is used below.

+	struct v4l2_fwnode_endpoint ep = { };
+	struct fwnode_handle *ep_handle;
+	struct v4l2_async_subdev *asd;
+	unsigned int lane;
+	int ret = -EINVAL;
+
+	if (of_property_read_u32(pdev->of_node, "num-data-lanes",

The binding now use brcm,num-data-lanes.

+				 &dev->max_data_lanes) < 0) {
+		dev_err(dev->v4l2_dev.dev, "number of data lanes not set\n");

		dev_err(dev->pdev, "DT property %s not set\n",
			"brcm,num-data-lanes");

+		return -EINVAL;
+	}
+
+	/* Get the local endpoint and remote device. */
+	ep_handle = fwnode_graph_get_endpoint_by_id(dev_fwnode(pdev), 0, 0,
+						    FWNODE_GRAPH_ENDPOINT_NEXT);
+	if (!ep_handle) {
+		dev_err(dev->v4l2_dev.dev, "No endpoint.\n");

s/endpoint./endpoint/

+		return -ENODEV;
+	}
+
+	/* Parse the local endpoint and validate its configuration. */
+	if (v4l2_fwnode_endpoint_alloc_parse(ep_handle, &ep)) {
+		dev_err(dev->v4l2_dev.dev, "could not parse endpoint\n");
+		goto cleanup_exit;
+	}
+
+	dev_dbg(dev->v4l2_dev.dev, "parsed local endpoint, bus_type %u\n",
+		ep.bus_type);
+
+	dev->bus_type = ep.bus_type;
+
+	switch (ep.bus_type) {
+	case V4L2_MBUS_CSI2_DPHY:
+		switch (ep.bus.mipi_csi2.num_data_lanes) {
+		case 1:
+		case 2:
+		case 4:
+			break;
+
+		default:
+			dev_err(dev->v4l2_dev.dev, "%u data lanes not supported\n",
+				ep.bus.mipi_csi2.num_data_lanes);
+			goto cleanup_exit;
+		}
+
+		for (lane = 0; lane < ep.bus.mipi_csi2.num_data_lanes; lane++) {
+			if (ep.bus.mipi_csi2.data_lanes[lane] != lane + 1) {
+				dev_err(dev->v4l2_dev.dev, "data lanes reordering not supported\n");
+				goto cleanup_exit;
+			}
+		}
+
+		if (ep.bus.mipi_csi2.num_data_lanes > dev->max_data_lanes) {
+			dev_err(dev->v4l2_dev.dev, "endpoint requires %u data lanes when %u are supported\n",
+				ep.bus.mipi_csi2.num_data_lanes,
+				dev->max_data_lanes);
+		}
+
+		dev->active_data_lanes = ep.bus.mipi_csi2.num_data_lanes;
+		dev->bus_flags = ep.bus.mipi_csi2.flags;
+
+		break;
+
+	case V4L2_MBUS_CCP2:
+		if (ep.bus.mipi_csi1.clock_lane != 0 ||
+		    ep.bus.mipi_csi1.data_lane != 1) {
+			dev_err(dev->v4l2_dev.dev, "unsupported lanes configuration\n");
+			goto cleanup_exit;
+		}
+
+		dev->max_data_lanes = 1;
+		dev->active_data_lanes = 1;
+			dev->bus_flags = ep.bus.mipi_csi1.strobe;

Wrong indentation.

+		break;
+
+	default:
+		/* Unsupported bus type */
+		dev_err(dev->v4l2_dev.dev, "unsupported bus type %u\n",
+			ep.bus_type);
+		goto cleanup_exit;
+	}
+
+	dev_dbg(dev->v4l2_dev.dev, "%s bus, %u data lanes, flags=0x%08x\n",
+		dev->bus_type == V4L2_MBUS_CSI2_DPHY ? "CSI-2" : "CCP2",
+		dev->active_data_lanes, dev->bus_flags);
+
+	/* Initialize and register the async notifier. */
+	v4l2_async_nf_init(&dev->notifier);
+
+	asd = v4l2_async_nf_add_fwnode_remote(&dev->notifier,
+					      ep_handle,

These two lines can fit into one.

+					      struct v4l2_async_subdev);
+
+	fwnode_handle_put(ep_handle);

	ep_handle = NULL;

or the cleanup path will release the reference a second time.

+
+	if (IS_ERR(asd)) {
+		ret = PTR_ERR(asd);
+		/* OK if asd already exists */

Why is that OK ?

+		if (ret != -EEXIST)
+			goto cleanup_exit;
+	}
+
+	dev->notifier.ops = &unicam_async_ops;
+
+	ret = v4l2_async_nf_register(&dev->v4l2_dev, &dev->notifier);
+	if (ret) {
+		dev_err(dev->v4l2_dev.dev, "Error registering device notifier: %d\n", ret);
+		goto cleanup_exit;
+	}
+
+	return 0;
+
+cleanup_exit:
+	v4l2_fwnode_endpoint_free(&ep);
+	fwnode_handle_put(ep_handle);
+
+	return ret;
+}
+
+static int bcm2835_media_dev_init(struct unicam_device *unicam,

bcm2835 stands out, you use unicam_ as a prefix everywhere else.

+				  struct platform_device *pdev)

Drop this argument and use unicam->pdev.

+{
+	unicam->mdev.dev = &pdev->dev;
+	strscpy(unicam->mdev.model, UNICAM_MODULE_NAME,
+		sizeof(unicam->mdev.model));
+	strscpy(unicam->mdev.serial, "", sizeof(unicam->mdev.serial));
+	snprintf(unicam->mdev.bus_info, sizeof(unicam->mdev.bus_info),
+		 "platform:%s", dev_name(&pdev->dev));

This line can be dropped once "[PATCH v2 0/4] Set bus_info field in
framework" gets merged.

+	unicam->mdev.hw_revision = 0;
+
+	media_device_init(&unicam->mdev);
+
+	unicam->v4l2_dev.mdev = &unicam->mdev;
+
+	return v4l2_device_register(&pdev->dev, &unicam->v4l2_dev);
+}
+
+static int unicam_init_and_register_subdev(struct unicam_device *unicam)

I'd move this function to the subdev section, just after
unicam_subdev_media_ops.

+{

	struct v4l2_subdev *sd = &unicam->subdev.sd;

will make the lines below shorter and easier to read.

+	int ret;
+
+	v4l2_subdev_init(&unicam->subdev.sd, &unicam_subdev_ops);
+	v4l2_set_subdevdata(&unicam->subdev.sd, unicam);
+	unicam->subdev.sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+	unicam->subdev.sd.dev = unicam->pdev;
+	unicam->subdev.sd.owner = THIS_MODULE;
+	unicam->subdev.sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_MULTIPLEXED;
+	snprintf(unicam->subdev.sd.name, sizeof(unicam->subdev.sd.name), "unicam-subdev");
+
+	unicam->subdev.pads[UNICAM_SD_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
+
+	unicam->subdev.pads[UNICAM_SD_PAD_SOURCE_IMAGE].flags = MEDIA_PAD_FL_SOURCE;
+	unicam->subdev.pads[UNICAM_SD_PAD_SOURCE_METADATA].flags = MEDIA_PAD_FL_SOURCE;
+
+	unicam->subdev.sd.entity.ops = &unicam_subdev_media_ops;

Move this line just after setting entity.function.

+	ret = media_entity_pads_init(&unicam->subdev.sd.entity,
+				     ARRAY_SIZE(unicam->subdev.pads), unicam->subdev.pads);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Could not init media controller for subdev");

You can use unicam->pdev. Same below.

s/controller for subdev/entity/

+		return ret;
+	}
+
+	ret = v4l2_subdev_init_finalize(&unicam->subdev.sd);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev, "Could not finalize init for subdev");
+		goto err_entity_cleanup;
+	}
+
+	return v4l2_device_register_subdev(&unicam->v4l2_dev, &unicam->subdev.sd);
+
+err_entity_cleanup:
+	media_entity_cleanup(&unicam->subdev.sd.entity);

This should be moved to unicam_release(). Drop it from unicam_probe()
too.

+	return ret;
+}
+
+static int unicam_probe(struct platform_device *pdev)
+{
+	struct unicam_device *unicam;
+	int ret = 0;
+
+	unicam = kzalloc(sizeof(*unicam), GFP_KERNEL);
+	if (!unicam)
+		return -ENOMEM;
+
+	kref_init(&unicam->kref);
+	unicam->pdev = &pdev->dev;
+
+	unicam->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(unicam->base)) {
+		ret = PTR_ERR(unicam->base);
+		goto err_unicam_put;
+	}
+
+	unicam->clk_gate_base = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(unicam->clk_gate_base)) {
+		ret = PTR_ERR(unicam->clk_gate_base);
+		goto err_unicam_put;
+	}
+
+	unicam->clock = devm_clk_get(&pdev->dev, "lp");
+	if (IS_ERR(unicam->clock)) {
+		dev_err(unicam->v4l2_dev.dev, "Failed to get lp clock\n");
+		ret = PTR_ERR(unicam->clock);
+		goto err_unicam_put;
+	}
+
+	unicam->vpu_clock = devm_clk_get(&pdev->dev, "vpu");
+	if (IS_ERR(unicam->vpu_clock)) {
+		dev_err(unicam->v4l2_dev.dev, "Failed to get vpu clock\n");
+		ret = PTR_ERR(unicam->vpu_clock);
+		goto err_unicam_put;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "No IRQ resource\n");
+		ret = -EINVAL;
+		goto err_unicam_put;
+	}
+
+	ret = devm_request_irq(&pdev->dev, ret, unicam_isr, 0,
+			       "unicam_capture0", unicam);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to request interrupt\n");
+		ret = -EINVAL;
+		goto err_unicam_put;
+	}
+
+	ret = bcm2835_media_dev_init(unicam, pdev);
+	if (ret) {
+		dev_err(unicam->v4l2_dev.dev,
+			"Unable to register v4l2 device.\n");
+		goto err_unicam_put;
+	}
+
+	ret = media_device_register(&unicam->mdev);

This can be moved to the bcm2835_media_dev_init() function, which could
then be renamed to unicam_init_and_register_media() to match
unicam_init_and_register_subdev().

Please double-check the cleanup path at the end of this function after
making this change.

+	if (ret < 0) {
+		dev_err(unicam->v4l2_dev.dev,
+			"Unable to register media-controller device.\n");
+		goto err_v4l2_unregister;
+	}
+
+	/* set the driver data in platform device */
+	platform_set_drvdata(pdev, unicam);

I'd move this line either to the top, just after setting unicam->pdev,
or to the bottom, just before returning. It's a bit lost here in the
middle.

-- 
Regards,

Laurent Pinchart

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