Re: [PATCH v5 04/11] media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface

Hi Stefan,

On Sun, Feb 13, 2022 at 12:17:25PM +0100, Stefan Wahren wrote:

Am 08.02.22 um 16:50 schrieb Jean-Michel Hautbois:

quoted

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>

---
v4:
  - Add the vendor prefox for DT name
  - Use the reg-names in DT parsing
  - Remove MAINTAINERS entry

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.
---
 drivers/media/platform/Kconfig                |    1 +
 drivers/media/platform/Makefile               |    2 +
 drivers/media/platform/bcm2835/Kconfig        |   21 +
 drivers/media/platform/bcm2835/Makefile       |    3 +
 .../platform/bcm2835/bcm2835-unicam-regs.h    |  253 ++
 .../media/platform/bcm2835/bcm2835-unicam.c   | 2570 +++++++++++++++++
 6 files changed, 2850 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-regs.h
 create mode 100644 drivers/media/platform/bcm2835/bcm2835-unicam.c

diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 9fbdba0fd1e7..033b0358fbb8 100644
--- a/drivers/media/platform/Kconfig
+++ b/drivers/media/platform/Kconfig

@@ -170,6 +170,7 @@ source "drivers/media/platform/am437x/Kconfig"
 source "drivers/media/platform/xilinx/Kconfig"
 source "drivers/media/platform/rcar-vin/Kconfig"
 source "drivers/media/platform/atmel/Kconfig"
+source "drivers/media/platform/bcm2835/Kconfig"
 source "drivers/media/platform/sunxi/Kconfig"
 
 config VIDEO_TI_CAL

diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
index 28eb4aadbf45..18894fc586aa 100644
--- a/drivers/media/platform/Makefile
+++ b/drivers/media/platform/Makefile

@@ -86,6 +86,8 @@ obj-$(CONFIG_VIDEO_QCOM_CAMSS)		+= qcom/camss/
 
 obj-$(CONFIG_VIDEO_QCOM_VENUS)		+= qcom/venus/
 
+obj-$(CONFIG_VIDEO_BCM2835_UNICAM)	+= bcm2835/
+
 obj-y					+= sunxi/
 
 obj-$(CONFIG_VIDEO_MESON_GE2D)		+= meson/ge2d/

diff --git a/drivers/media/platform/bcm2835/Kconfig b/drivers/media/platform/bcm2835/Kconfig
new file mode 100644
index 000000000000..1691541da905
--- /dev/null
+++ b/drivers/media/platform/bcm2835/Kconfig

@@ -0,0 +1,21 @@
+# Broadcom VideoCore4 V4L2 camera support
+
+config VIDEO_BCM2835_UNICAM
+	tristate "Broadcom BCM283x/BCM271x Unicam video capture driver"
+	depends on ARCH_BCM2835 || COMPILE_TEST
+	depends on VIDEO_V4L2
+	select MEDIA_CONTROLLER
+	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_FWNODE
+	select VIDEOBUF2_DMA_CONTIG
+	help
+	  Say Y here to enable support for the BCM283x/BCM271x CSI-2 receiver.
+	  This is a V4L2 driver that controls the CSI-2 receiver directly,
+	  independently from the VC4 firmware.
+	  This driver is mutually exclusive with the use of bcm2835-camera. The
+	  firmware will disable all access to the peripheral from within the
+	  firmware if it finds a DT node using it, and bcm2835-camera will
+	  therefore fail to probe.

would be nice to know, what is the exact condition for the firmware. The
compatible and must its status be enabled?

quoted

+
+	  To compile this driver as a module, choose M here. The module will be
+	  called bcm2835-unicam.

[snip]

quoted

diff --git a/drivers/media/platform/bcm2835/bcm2835-unicam.c b/drivers/media/platform/bcm2835/bcm2835-unicam.c
new file mode 100644
index 000000000000..470e691637c7
--- /dev/null
+++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c

@@ -0,0 +1,2570 @@

[snip]

quoted

+static inline bool unicam_sd_pad_is_sink(u32 pad)
+{
+	/* Camera RX has 1 sink pad, and N source pads */
+	return pad == 0;
+}

s/0/UNICAM_SD_PAD_SINK ?

Good idea.

quoted

+
+static inline bool unicam_sd_pad_is_source(u32 pad)
+{
+	/* Camera RX has 1 sink pad, and N source pads */
+	return pad != UNICAM_SD_PAD_SINK;
+}
+
+enum unicam_node_type {
+	UNICAM_IMAGE_NODE,
+	UNICAM_METADATA_NODE,
+	UNICAM_MAX_NODES
+};
+
+/* -----------------------------------------------------------------------------
+ * Structure definitions
+ */

please drop

I really favour splitting code in sections, it makes it more readable.
At the end of the day I think this is a personal decision for the
author, if no specific policy is enforced at the subsystem level.

[snip]

quoted

+/*
+ * unicam_isr : ISR handler for unicam capture
+ * @irq: irq number
+ * @dev_id: dev_id ptr

these kernel-doc doesn't match with the definition. dev seems to be the
unicam instance?

I'd drop the comment as it doesn't really contain much useful information.

quoted

+ *
+ * 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)

[snip]

-- 
Regards,

Laurent Pinchart