Thread (24 messages) 24 messages, 7 authors, 2025-03-09

Re: [PATCH 2/6] drm/bridge: synopsys: Add DW DPTX Controller support library

From: Dmitry Baryshkov <hidden>
Date: 2025-03-04 09:18:53
Also in: dri-devel, linux-devicetree, linux-rockchip, lkml

On Tue, Mar 04, 2025 at 03:16:16PM +0800, Andy Yan wrote:
Hi Dmitry,

在 2025-03-03 00:21:06,"Dmitry Baryshkov" [off-list ref] 写道:
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On Sun, Mar 02, 2025 at 06:34:22PM +0800, Andy Yan wrote:
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Hi Dmitry,
   Thank you for your review。
   Please also review my inline reply.
      
在 2025-03-02 02:14:19,"Dmitry Baryshkov" [off-list ref] 写道:
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On Sun, Feb 23, 2025 at 07:30:25PM +0800, Andy Yan wrote:
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From: Andy Yan <andy.yan@rock-chips.com>

The DW DP TX Controller is compliant with the DisplayPort Specification
Version 1.4 with the following features:

* DisplayPort 1.4a
* Main Link: 1/2/4 lanes
* Main Link Support 1.62Gbps, 2.7Gbps, 5.4Gbps and 8.1Gbps
* AUX channel 1Mbps
* Single Stream Transport(SST)
* Multistream Transport (MST)
*Type-C support (alternate mode)
* HDCP 2.2, HDCP 1.3
* Supports up to 8/10 bits per color component
* Supports RBG, YCbCr4:4:4, YCbCr4:2:2, YCbCr4:2:0
* Pixel clock up to 594MHz
* I2S, SPDIF audio interface

Add library with common helpers to make it can be shared with
other SoC.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>

drm/bridge: cleanup
Stray line?
Sorry, will be removed.
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+static int dw_dp_link_power_up(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+	int ret;
+	u8 value;
+
+	if (link->revision < DP_DPCD_REV_11)
+		return 0;
+
+	ret = drm_dp_dpcd_readb(&dp->aux, DP_SET_POWER, &value);
+	if (ret < 0)
+		return ret;
+
+	value &= ~DP_SET_POWER_MASK;
+	value |= DP_SET_POWER_D0;
+
+	ret = drm_dp_dpcd_writeb(&dp->aux, DP_SET_POWER, value);
+	if (ret < 0)
+		return ret;
+
+	usleep_range(1000, 2000);
+
+	return 0;
+}
+
+static int dw_dp_link_power_down(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+	int ret;
+	u8 value;
+
+	if (link->revision < DP_DPCD_REV_11)
+		return 0;
+
+	ret = drm_dp_dpcd_readb(&dp->aux, DP_SET_POWER, &value);
+	if (ret < 0)
+		return ret;
+
+	value &= ~DP_SET_POWER_MASK;
+	value |= DP_SET_POWER_D3;
+
+	ret = drm_dp_dpcd_writeb(&dp->aux, DP_SET_POWER, value);
+	if (ret < 0)
+		return ret;
+
Would you please mind pulling these two functions to DRM DP helpers?
There are enough users to make this into a common code.
Yes, when developing this patch, I had the same realization. 
The processing logic for MSM/Cadence/ANX6345/tegra follows
a similar approach.
I had originally planned to defer this refactoring until the series of patches is accepted. 
Additionally, I have other pending tasks in my TODO list, such as fully decoupling the 
bridge driver and encoder/connector components across all Rockchip platforms。
But I prioritize completing these foundational features before go to next steps,
Is this acceptable ?
You can add necessary helpers as one of the first patches in the
series. Convert one or several platforms that use drm-misc (i.e. not
MSM, AMD, i915, nouveau) and send conversion of the rest of the
platforms as followups.
If  pull these two functions to DRM DP helpers, I think they should be
named as drm_dp_link_power_up/down ?.
I think so.
I found that tegra/dp.c already use this name, so I need to do a symbols rename
for tegra first to avoid build error like[2].

Can the patch for Tegra be merged  through  drm-misc branch?
Yes, when drm_dp_link code was moved to the Tegra driver, nobody renamed
those symboles. Maybe in the hope of moving them back. Please rename
those symbols.

[2]https://lore.kernel.org/oe-kbuild-all/202410250305.UHKDhtxy-lkp@intel.com/ (local)
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+	return 0;
+}
+
+static bool dw_dp_has_sink_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				 const struct drm_dp_desc *desc)
+{
+	return dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
+	       dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
+	       !drm_dp_has_quirk(desc, DP_DPCD_QUIRK_NO_SINK_COUNT);

isn't it drm_dp_read_sink_count_cap() ?
I will have a try, since this drm_dp_read_sink_count_cap requires a connector parameter, 
I need to figure out how to get the connector here.
Maybe Maxime's series will you here, see [1].

[1] https://lore.kernel.org/dri-devel/20250225-bridge-connector-v4-4-7ecb07b09cad@kernel.org/ (local)
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+}
+
+static int dw_dp_link_parse(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+	u8 dpcd;
+	int ret;
......
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+		break;
+	}
+
+	if (video->color_format == DRM_COLOR_FORMAT_RGB444) {
+		vsc.colorimetry = DP_COLORIMETRY_DEFAULT;
+		vsc.dynamic_range = DP_DYNAMIC_RANGE_VESA;
+	} else {
+		vsc.colorimetry = DP_COLORIMETRY_BT709_YCC;
+		vsc.dynamic_range = DP_DYNAMIC_RANGE_CTA;
+	}
+
+	vsc.bpc = video->bpc;
+	vsc.content_type = DP_CONTENT_TYPE_NOT_DEFINED;
+
+	dw_dp_vsc_sdp_pack(&vsc, &sdp);
+
+	return dw_dp_send_sdp(dp, &sdp);
+}
+
+static int dw_dp_video_set_pixel_mode(struct dw_dp *dp, u8 pixel_mode)
+{
+	switch (pixel_mode) {
+	case DW_DP_MP_SINGLE_PIXEL:
+	case DW_DP_MP_DUAL_PIXEL:
+	case DW_DP_MP_QUAD_PIXEL:
+		break;
+	default:
+		return -EINVAL;
Is it possible?
This IP is configurable for single/dual/quad pixel modes。
It's  quad pixel mode on rk3588 and dual pixel mode on rk3576,
so we add this check here.
My question was slightly different: is it possible to end up here in the
'default' branch?
Sorry, I think I didn't get your key point here.
If someone give a invalid pixe mode(not any of SINGLE/DUAL/QUAD_PIXEL ), 
then we go to default branch return -ENVIAL,  then the dp_bridge enable stop.
This is what we want here.



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+	}
+
+	regmap_update_bits(dp->regmap, DW_DP_VSAMPLE_CTRL, PIXEL_MODE_SELECT,
+			   FIELD_PREP(PIXEL_MODE_SELECT, pixel_mode));
+
+	return 0;
+}
+
+static bool dw_dp_video_need_vsc_sdp(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+	struct dw_dp_video *video = &dp->video;
+
+	if (!link->vsc_sdp_supported)
+		return false;
+
+	if (video->color_format == DRM_COLOR_FORMAT_YCBCR420)
+		return true;
+
+	return false;
+}
+
+static int dw_dp_video_set_msa(struct dw_dp *dp, u8 color_format, u8 bpc,
+			       u16 vstart, u16 hstart)
+{
+	u16 misc = 0;
+
+	if (dw_dp_video_need_vsc_sdp(dp))
+		misc |= DP_MSA_MISC_COLOR_VSC_SDP;
+
+	switch (color_format) {
+	case DRM_COLOR_FORMAT_RGB444:
+		misc |= DP_MSA_MISC_COLOR_RGB;
+		break;
+	case DRM_COLOR_FORMAT_YCBCR444:
+		misc |= DP_MSA_MISC_COLOR_YCBCR_444_BT709;
+		break;
+	case DRM_COLOR_FORMAT_YCBCR422:
+		misc |= DP_MSA_MISC_COLOR_YCBCR_422_BT709;
+		break;
+	case DRM_COLOR_FORMAT_YCBCR420:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (bpc) {
+	case 6:
+		misc |= DP_MSA_MISC_6_BPC;
+		break;
+	case 8:
+		misc |= DP_MSA_MISC_8_BPC;
+		break;
+	case 10:
+		misc |= DP_MSA_MISC_10_BPC;
+		break;
+	case 12:
+		misc |= DP_MSA_MISC_12_BPC;
+		break;
+	case 16:
+		misc |= DP_MSA_MISC_16_BPC;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap_write(dp->regmap, DW_DP_VIDEO_MSA1,
+		     FIELD_PREP(VSTART, vstart) | FIELD_PREP(HSTART, hstart));
+	regmap_write(dp->regmap, DW_DP_VIDEO_MSA2, FIELD_PREP(MISC0, misc));
+	regmap_write(dp->regmap, DW_DP_VIDEO_MSA3, FIELD_PREP(MISC1, misc >> 8));
+
+	return 0;
+}
+
+static void dw_dp_video_disable(struct dw_dp *dp)
+{
+	regmap_update_bits(dp->regmap, DW_DP_VSAMPLE_CTRL, VIDEO_STREAM_ENABLE,
+			   FIELD_PREP(VIDEO_STREAM_ENABLE, 0));
+}
+
+static int dw_dp_video_enable(struct dw_dp *dp)
+{
+	struct dw_dp_video *video = &dp->video;
+	struct dw_dp_link *link = &dp->link;
+	struct drm_display_mode *mode = &video->mode;
+	u8 color_format = video->color_format;
+	u8 bpc = video->bpc;
+	u8 pixel_mode = video->pixel_mode;
+	u8 bpp = video->bpp, init_threshold, vic;
+	u32 hactive, hblank, h_sync_width, h_front_porch;
+	u32 vactive, vblank, v_sync_width, v_front_porch;
+	u32 vstart = mode->vtotal - mode->vsync_start;
+	u32 hstart = mode->htotal - mode->hsync_start;
+	u32 peak_stream_bandwidth, link_bandwidth;
+	u32 average_bytes_per_tu, average_bytes_per_tu_frac;
+	u32 ts, hblank_interval;
+	u32 value;
+	int ret;
+
+	ret = dw_dp_video_set_pixel_mode(dp, pixel_mode);
+	if (ret)
+		return ret;
+
+	ret = dw_dp_video_set_msa(dp, color_format, bpc, vstart, hstart);
+	if (ret)
+		return ret;
+
+	regmap_update_bits(dp->regmap, DW_DP_VSAMPLE_CTRL, VIDEO_MAPPING,
+			   FIELD_PREP(VIDEO_MAPPING, video->video_mapping));
+
+	/* Configure DW_DP_VINPUT_POLARITY_CTRL register */
+	value = 0;
+	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
+		value |= FIELD_PREP(HSYNC_IN_POLARITY, 1);
+	if (mode->flags & DRM_MODE_FLAG_PVSYNC)
+		value |= FIELD_PREP(VSYNC_IN_POLARITY, 1);
+	regmap_write(dp->regmap, DW_DP_VINPUT_POLARITY_CTRL, value);
+
+	/* Configure DW_DP_VIDEO_CONFIG1 register */
+	hactive = mode->hdisplay;
+	hblank = mode->htotal - mode->hdisplay;
+	value = FIELD_PREP(HACTIVE, hactive) | FIELD_PREP(HBLANK, hblank);
+	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+		value |= FIELD_PREP(I_P, 1);
+	vic = drm_match_cea_mode(mode);
+	if (vic == 5 || vic == 6 || vic == 7 ||
+	    vic == 10 || vic == 11 || vic == 20 ||
+	    vic == 21 || vic == 22 || vic == 39 ||
+	    vic == 25 || vic == 26 || vic == 40 ||
+	    vic == 44 || vic == 45 || vic == 46 ||
+	    vic == 50 || vic == 51 || vic == 54 ||
+	    vic == 55 || vic == 58 || vic  == 59)
+		value |= R_V_BLANK_IN_OSC;
+	regmap_write(dp->regmap, DW_DP_VIDEO_CONFIG1, value);
+
+	/* Configure DW_DP_VIDEO_CONFIG2 register */
+	vblank = mode->vtotal - mode->vdisplay;
+	vactive = mode->vdisplay;
+	regmap_write(dp->regmap, DW_DP_VIDEO_CONFIG2,
+		     FIELD_PREP(VBLANK, vblank) | FIELD_PREP(VACTIVE, vactive));
+
+	/* Configure DW_DP_VIDEO_CONFIG3 register */
+	h_sync_width = mode->hsync_end - mode->hsync_start;
+	h_front_porch = mode->hsync_start - mode->hdisplay;
+	regmap_write(dp->regmap, DW_DP_VIDEO_CONFIG3,
+		     FIELD_PREP(H_SYNC_WIDTH, h_sync_width) |
+		     FIELD_PREP(H_FRONT_PORCH, h_front_porch));
+
+	/* Configure DW_DP_VIDEO_CONFIG4 register */
+	v_sync_width = mode->vsync_end - mode->vsync_start;
+	v_front_porch = mode->vsync_start - mode->vdisplay;
+	regmap_write(dp->regmap, DW_DP_VIDEO_CONFIG4,
+		     FIELD_PREP(V_SYNC_WIDTH, v_sync_width) |
+		     FIELD_PREP(V_FRONT_PORCH, v_front_porch));
+
+	/* Configure DW_DP_VIDEO_CONFIG5 register */
+	peak_stream_bandwidth = mode->clock * bpp / 8;
+	link_bandwidth = (link->rate / 1000) * link->lanes;
+	ts = peak_stream_bandwidth * 64 / link_bandwidth;
+	average_bytes_per_tu = ts / 1000;
+	average_bytes_per_tu_frac = ts / 100 - average_bytes_per_tu * 10;
+	if (pixel_mode == DW_DP_MP_SINGLE_PIXEL) {
+		if (average_bytes_per_tu < 6)
+			init_threshold = 32;
+		else if (hblank <= 80 && color_format != DRM_COLOR_FORMAT_YCBCR420)
+			init_threshold = 12;
+		else if (hblank <= 40 && color_format == DRM_COLOR_FORMAT_YCBCR420)
+			init_threshold = 3;
+		else
+			init_threshold = 16;
+	} else {
+		u32 t1 = 0, t2 = 0, t3 = 0;
+
+		switch (bpc) {
+		case 6:
+			t1 = (4 * 1000 / 9) * link->lanes;
+			break;
+		case 8:
+			if (color_format == DRM_COLOR_FORMAT_YCBCR422) {
+				t1 = (1000 / 2) * link->lanes;
+			} else {
+				if (pixel_mode == DW_DP_MP_DUAL_PIXEL)
+					t1 = (1000 / 3) * link->lanes;
+				else
+					t1 = (3000 / 16) * link->lanes;
+			}
+			break;
+		case 10:
+			if (color_format == DRM_COLOR_FORMAT_YCBCR422)
+				t1 = (2000 / 5) * link->lanes;
+			else
+				t1 = (4000 / 15) * link->lanes;
+			break;
+		case 12:
+			if (color_format == DRM_COLOR_FORMAT_YCBCR422) {
+				if (pixel_mode == DW_DP_MP_DUAL_PIXEL)
+					t1 = (1000 / 6) * link->lanes;
+				else
+					t1 = (1000 / 3) * link->lanes;
+			} else {
+				t1 = (2000 / 9) * link->lanes;
+			}
+			break;
+		case 16:
+			if (color_format != DRM_COLOR_FORMAT_YCBCR422 &&
+			    pixel_mode == DW_DP_MP_DUAL_PIXEL)
+				t1 = (1000 / 6) * link->lanes;
+			else
+				t1 = (1000 / 4) * link->lanes;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		if (color_format == DRM_COLOR_FORMAT_YCBCR420)
+			t2 = (link->rate / 4) * 1000 / (mode->clock / 2);
+		else
+			t2 = (link->rate / 4) * 1000 / mode->clock;
+
+		if (average_bytes_per_tu_frac)
+			t3 = average_bytes_per_tu + 1;
+		else
+			t3 = average_bytes_per_tu;
+		init_threshold = t1 * t2 * t3 / (1000 * 1000);
+		if (init_threshold <= 16 || average_bytes_per_tu < 10)
+			init_threshold = 40;
+	}
+
+	regmap_write(dp->regmap, DW_DP_VIDEO_CONFIG5,
+		     FIELD_PREP(INIT_THRESHOLD_HI, init_threshold >> 6) |
+		     FIELD_PREP(AVERAGE_BYTES_PER_TU_FRAC, average_bytes_per_tu_frac) |
+		     FIELD_PREP(INIT_THRESHOLD, init_threshold) |
+		     FIELD_PREP(AVERAGE_BYTES_PER_TU, average_bytes_per_tu));
+
+	/* Configure DW_DP_VIDEO_HBLANK_INTERVAL register */
+	hblank_interval = hblank * (link->rate / 4) / mode->clock;
+	regmap_write(dp->regmap, DW_DP_VIDEO_HBLANK_INTERVAL,
+		     FIELD_PREP(HBLANK_INTERVAL_EN, 1) |
+		     FIELD_PREP(HBLANK_INTERVAL, hblank_interval));
+
+	/* Video stream enable */
+	regmap_update_bits(dp->regmap, DW_DP_VSAMPLE_CTRL, VIDEO_STREAM_ENABLE,
+			   FIELD_PREP(VIDEO_STREAM_ENABLE, 1));
+
+	if (dw_dp_video_need_vsc_sdp(dp))
+		dw_dp_send_vsc_sdp(dp);
+
+	return 0;
+}
+
+static void dw_dp_hpd_init(struct dw_dp *dp)
+{
+	/* Enable all HPD interrupts */
+	regmap_update_bits(dp->regmap, DW_DP_HPD_INTERRUPT_ENABLE,
+			   HPD_UNPLUG_EN | HPD_PLUG_EN | HPD_IRQ_EN,
+			   FIELD_PREP(HPD_UNPLUG_EN, 1) |
+			   FIELD_PREP(HPD_PLUG_EN, 1) |
+			   FIELD_PREP(HPD_IRQ_EN, 1));
+
+	/* Enable all top-level interrupts */
+	regmap_update_bits(dp->regmap, DW_DP_GENERAL_INTERRUPT_ENABLE,
+			   HPD_EVENT_EN, FIELD_PREP(HPD_EVENT_EN, 1));
+}
+
+static void dw_dp_aux_init(struct dw_dp *dp)
+{
+	regmap_update_bits(dp->regmap, DW_DP_GENERAL_INTERRUPT_ENABLE,
+			   AUX_REPLY_EVENT_EN, FIELD_PREP(AUX_REPLY_EVENT_EN, 1));
+}
+
+static void dw_dp_init_hw(struct dw_dp *dp)
+{
+	regmap_update_bits(dp->regmap, DW_DP_CCTL, DEFAULT_FAST_LINK_TRAIN_EN,
+			   FIELD_PREP(DEFAULT_FAST_LINK_TRAIN_EN, 0));
+
+	dw_dp_hpd_init(dp);
+	dw_dp_aux_init(dp);
+}
+
+static int dw_dp_aux_write_data(struct dw_dp *dp, const u8 *buffer, size_t size)
+{
+	size_t i, j;
+
+	for (i = 0; i < DIV_ROUND_UP(size, 4); i++) {
+		size_t num = min_t(size_t, size - i * 4, 4);
+		u32 value = 0;
+
+		for (j = 0; j < num; j++)
+			value |= buffer[i * 4 + j] << (j * 8);
+
+		regmap_write(dp->regmap, DW_DP_AUX_DATA0 + i * 4, value);
+	}
+
+	return size;
+}
+
+static int dw_dp_aux_read_data(struct dw_dp *dp, u8 *buffer, size_t size)
+{
+	size_t i, j;
+
+	for (i = 0; i < DIV_ROUND_UP(size, 4); i++) {
+		size_t num = min_t(size_t, size - i * 4, 4);
+		u32 value;
+
+		regmap_read(dp->regmap, DW_DP_AUX_DATA0 + i * 4, &value);
+
+		for (j = 0; j < num; j++)
+			buffer[i * 4 + j] = value >> (j * 8);
+	}
+
+	return size;
+}
+
+static ssize_t dw_dp_aux_transfer(struct drm_dp_aux *aux,
+				  struct drm_dp_aux_msg *msg)
+{
+	struct dw_dp *dp = container_of(aux, struct dw_dp, aux);
+	unsigned long timeout = msecs_to_jiffies(10);
+	u32 status, value;
+	ssize_t ret = 0;
+
+	if (WARN_ON(msg->size > 16))
+		return -E2BIG;
+
+	switch (msg->request & ~DP_AUX_I2C_MOT) {
+	case DP_AUX_NATIVE_WRITE:
+	case DP_AUX_I2C_WRITE:
+	case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+		ret = dw_dp_aux_write_data(dp, msg->buffer, msg->size);
+		if (ret < 0)
+			return ret;
+		break;
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (msg->size > 0)
+		value = FIELD_PREP(AUX_LEN_REQ, msg->size - 1);
+	else
+		value = FIELD_PREP(I2C_ADDR_ONLY, 1);
+	value |= FIELD_PREP(AUX_CMD_TYPE, msg->request);
+	value |= FIELD_PREP(AUX_ADDR, msg->address);
+	regmap_write(dp->regmap, DW_DP_AUX_CMD, value);
+
+	status = wait_for_completion_timeout(&dp->complete, timeout);
+	if (!status) {
+		dev_err(dp->dev, "timeout waiting for AUX reply\n");
+		return -ETIMEDOUT;
+	}
+
+	regmap_read(dp->regmap, DW_DP_AUX_STATUS, &value);
+	if (value & AUX_TIMEOUT)
+		return -ETIMEDOUT;
+
+	msg->reply = FIELD_GET(AUX_STATUS, value);
+
+	if (msg->size > 0 && msg->reply == DP_AUX_NATIVE_REPLY_ACK) {
+		if (msg->request & DP_AUX_I2C_READ) {
+			size_t count = FIELD_GET(AUX_BYTES_READ, value) - 1;
+
+			if (count != msg->size)
+				return -EBUSY;
+
+			ret = dw_dp_aux_read_data(dp, msg->buffer, count);
+			if (ret < 0)
+				return ret;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Limits for the video timing output by DP:
+ * 1. the hfp should be 2 pixels aligned;
+ * 2. the minimum hsync should be 9 pixel;
+ * 3. the minimum hbp should be 16 pixel;
+ */
+static bool dw_dp_bridge_mode_fixup(struct drm_bridge *bridge,
+				    const struct drm_display_mode *mode,
+				    struct drm_display_mode *adjusted_mode)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	int min_hbp = 16;
+	int min_hsync = 9;
+
+	if ((adjusted_mode->hsync_start - adjusted_mode->hdisplay) & 0x1) {
+		adjusted_mode->hsync_start += 1;
+		dev_warn(dp->dev, "hfp is not 2 pixeel aligned, fixup to aligned hfp\n");
+	}
+	if (adjusted_mode->hsync_end - adjusted_mode->hsync_start < min_hsync) {
+		adjusted_mode->hsync_end = adjusted_mode->hsync_start + min_hsync;
+		dev_warn(dp->dev, "hsync is too narrow, fixup to min hsync:%d\n", min_hsync);
+	}
+	if (adjusted_mode->htotal - adjusted_mode->hsync_end < min_hbp) {
+		adjusted_mode->htotal = adjusted_mode->hsync_end + min_hbp;
+		dev_warn(dp->dev, "hbp is too narrow, fixup to min hbp:%d\n", min_hbp);
+	}
+
+	return true;
+}
+
+static enum drm_mode_status dw_dp_bridge_mode_valid(struct drm_bridge *bridge,
+						    const struct drm_display_info *info,
+						    const struct drm_display_mode *mode)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	struct dw_dp_link *link = &dp->link;
+	u32 min_bpp;
+
+	if (info->color_formats & DRM_COLOR_FORMAT_YCBCR420 &&
+	    link->vsc_sdp_supported &&
+	    (drm_mode_is_420_only(info, mode) || drm_mode_is_420_also(info, mode)))
+		min_bpp = 12;
+	else if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
+		min_bpp = 16;
+	else if (info->color_formats & DRM_COLOR_FORMAT_RGB444)
+		min_bpp = 18;
+	else
+		min_bpp = 24;
+
+	if (!link->vsc_sdp_supported &&
+	    drm_mode_is_420_only(info, mode))
+		return MODE_NO_420;
+
+	if (!dw_dp_bandwidth_ok(dp, mode, min_bpp, link->lanes, link->rate))
+		return MODE_CLOCK_HIGH;
+
+	return MODE_OK;
+}
+
+static void dw_dp_bridge_atomic_pre_enable(struct drm_bridge *bridge,
+					   struct drm_bridge_state *old_bridge_state)
+{
+	struct drm_atomic_state *state = old_bridge_state->base.state;
+	struct drm_crtc_state *crtc_state = bridge->encoder->crtc->state;
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	struct dw_dp_video *video = &dp->video;
+	struct drm_display_mode *m = &video->mode;
+	struct drm_bridge_state *bridge_state;
+	const struct dw_dp_output_format *fmt;
+
+	drm_mode_copy(m, &crtc_state->adjusted_mode);
+
+	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
+	fmt = dw_dp_get_output_format(bridge_state->output_bus_cfg.format);
Should it be a part of the atomic_check() instead?
Since we have modef_fixup in this driver, which is mutually exclusive with atomic_check.
You can convet .mode_fixup into .atomic_check. The latter can change the
crtc_state->adjusted_mode. It is better to reject the invalid
combinations from the .atomic_check rather than having to handled them
later.
quoted

quoted
quoted
+
+	video->video_mapping = fmt->video_mapping;
+	video->color_format = fmt->color_format;
+	video->bpc = fmt->bpc;
+	video->bpp = fmt->bpp;
+}
+
+static bool dw_dp_needs_link_retrain(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+	u8 link_status[DP_LINK_STATUS_SIZE];
+
+	if (!dw_dp_link_train_valid(&link->train))
+		return false;
+
+	if (drm_dp_dpcd_read_link_status(&dp->aux, link_status) < 0)
+		return false;
+
+	/* Retrain if Channel EQ or CR not ok */
+	return !drm_dp_channel_eq_ok(link_status, dp->link.lanes);
+}
+
+static void dw_dp_link_disable(struct dw_dp *dp)
+{
+	struct dw_dp_link *link = &dp->link;
+
+	if (dw_dp_hpd_detect(dp))
+		dw_dp_link_power_down(dp);
+
+	dw_dp_phy_xmit_enable(dp, 0);
+
+	phy_power_off(dp->phy);
+
+	link->train.clock_recovered = false;
+	link->train.channel_equalized = false;
+}
+
+static int dw_dp_link_enable(struct dw_dp *dp)
+{
+	int ret;
+
+	ret = phy_power_on(dp->phy);
+	if (ret)
+		return ret;
+
+	ret = dw_dp_link_power_up(dp);
+	if (ret < 0)
+		return ret;
+
+	ret = dw_dp_link_train(dp);
+
+	return ret;
+}
+
+static void dw_dp_bridge_atomic_enable(struct drm_bridge *bridge,
+				       struct drm_bridge_state *old_state)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	struct drm_atomic_state *state = old_state->base.state;
+	struct drm_connector *connector;
+	struct drm_connector_state *conn_state;
+	int ret;
+
+	connector = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
+	if (!connector) {
+		dev_err(dp->dev, "failed to get connector\n");
+		return;
+	}
+
+	conn_state = drm_atomic_get_new_connector_state(state, connector);
+	if (!conn_state) {
+		dev_err(dp->dev, "failed to get connector state\n");
+		return;
+	}
+
+	set_bit(0, dp->sdp_reg_bank);
+
+	ret = dw_dp_link_enable(dp);
+	if (ret < 0) {
+		dev_err(dp->dev, "failed to enable link: %d\n", ret);
+		return;
+	}
+
+	ret = dw_dp_video_enable(dp);
+	if (ret < 0) {
+		dev_err(dp->dev, "failed to enable video: %d\n", ret);
+		return;
+	}
+}
+
+static void dw_dp_reset(struct dw_dp *dp)
+{
+	int val;
+
+	disable_irq(dp->irq);
+	regmap_update_bits(dp->regmap, DW_DP_SOFT_RESET_CTRL, CONTROLLER_RESET,
+			   FIELD_PREP(CONTROLLER_RESET, 1));
+	udelay(10);
+	regmap_update_bits(dp->regmap, DW_DP_SOFT_RESET_CTRL, CONTROLLER_RESET,
+			   FIELD_PREP(CONTROLLER_RESET, 0));
+
+	dw_dp_init_hw(dp);
+	regmap_read_poll_timeout(dp->regmap, DW_DP_HPD_STATUS, val,
+				 FIELD_GET(HPD_HOT_PLUG, val), 200, 200000);
+	regmap_write(dp->regmap, DW_DP_HPD_STATUS, HPD_HOT_PLUG);
+	enable_irq(dp->irq);
+}
+
+static void dw_dp_bridge_atomic_disable(struct drm_bridge *bridge,
+					struct drm_bridge_state *old_bridge_state)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+
+	dw_dp_video_disable(dp);
+	dw_dp_link_disable(dp);
+	bitmap_zero(dp->sdp_reg_bank, SDP_REG_BANK_SIZE);
+	dw_dp_reset(dp);
+}
+
+static bool dw_dp_hpd_detect_link(struct dw_dp *dp)
+{
+	int ret;
+
+	ret = phy_power_on(dp->phy);
+	if (ret < 0)
+		return false;
+	ret = dw_dp_link_parse(dp);
+	phy_power_off(dp->phy);
+
+	return !ret;
+}
+
+static enum drm_connector_status dw_dp_bridge_detect(struct drm_bridge *bridge)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+
+	if (!dw_dp_hpd_detect(dp))
+		return connector_status_disconnected;
+
+	if (!dw_dp_hpd_detect_link(dp))
+		return connector_status_disconnected;
+
+	return connector_status_connected;
+}
+
+static const struct drm_edid *dw_dp_bridge_edid_read(struct drm_bridge *bridge,
+						     struct drm_connector *connector)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	const struct drm_edid *edid;
+	int ret;
+
+	ret = phy_power_on(dp->phy);
+	if (ret)
+		return NULL;
+
+	edid = drm_edid_read_ddc(connector, &dp->aux.ddc);
+
+	phy_power_off(dp->phy);
+
+	return edid;
+}
+
+static u32 *dw_dp_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
+						    struct drm_bridge_state *bridge_state,
+						    struct drm_crtc_state *crtc_state,
+						    struct drm_connector_state *conn_state,
+						    unsigned int *num_output_fmts)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+	struct dw_dp_link *link = &dp->link;
+	struct drm_display_info *di = &conn_state->connector->display_info;
+	struct drm_display_mode mode = crtc_state->mode;
+	const struct dw_dp_output_format *fmt;
+	u32 i, j = 0;
+	u32 *output_fmts;
+
+	*num_output_fmts = 0;
+
+	output_fmts = kcalloc(ARRAY_SIZE(dw_dp_output_formats), sizeof(*output_fmts), GFP_KERNEL);
+	if (!output_fmts)
+		return NULL;
+
+	for (i = 0; i < ARRAY_SIZE(dw_dp_output_formats); i++) {
+		fmt = &dw_dp_output_formats[i];
+
+		if (fmt->bpc > conn_state->max_bpc)
+			continue;
+
+		if (!(fmt->color_format & di->color_formats))
+			continue;
+
+		if (fmt->color_format == DRM_COLOR_FORMAT_YCBCR420 &&
+		    !link->vsc_sdp_supported)
+			continue;
+
+		if (fmt->color_format != DRM_COLOR_FORMAT_YCBCR420 &&
+		    drm_mode_is_420_only(di, &mode))
+			continue;
+
+		if (!dw_dp_bandwidth_ok(dp, &mode, fmt->bpp, link->lanes, link->rate))
+			continue;
+
+		output_fmts[j++] = fmt->bus_format;
+	}
+
+	*num_output_fmts = j;
+
+	return output_fmts;
+}
+
+static const struct drm_bridge_funcs dw_dp_bridge_funcs = {
+	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+	.atomic_reset = drm_atomic_helper_bridge_reset,
+	.atomic_get_input_bus_fmts = drm_atomic_helper_bridge_propagate_bus_fmt,
+	.atomic_get_output_bus_fmts = dw_dp_bridge_atomic_get_output_bus_fmts,
+	.mode_fixup = dw_dp_bridge_mode_fixup,
+	.mode_valid = dw_dp_bridge_mode_valid,
+	.atomic_pre_enable = dw_dp_bridge_atomic_pre_enable,
+	.atomic_enable = dw_dp_bridge_atomic_enable,
+	.atomic_disable = dw_dp_bridge_atomic_disable,
+	.detect = dw_dp_bridge_detect,
+	.edid_read = dw_dp_bridge_edid_read,
+};
+
+static int dw_dp_link_retrain(struct dw_dp *dp)
+{
+	struct drm_device *dev = dp->bridge.dev;
+	struct drm_modeset_acquire_ctx ctx;
+	int ret;
+
+	if (!dw_dp_needs_link_retrain(dp))
+		return 0;
+
+	dev_dbg(dp->dev, "Retraining link\n");
+
+	drm_modeset_acquire_init(&ctx, 0);
+	for (;;) {
+		ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
+		if (ret != -EDEADLK)
+			break;
I think it's an error to continue in such a case. There should be a
return after the loop if ret is not 0.
Thank you for catching this, I will add a check fater the loop.

quoted
quoted
+
+		drm_modeset_backoff(&ctx);
+	}
+
+	ret = dw_dp_link_train(dp);
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+}
+
+static void dw_dp_hpd_work(struct work_struct *work)
+{
+	struct dw_dp *dp = container_of(work, struct dw_dp, hpd_work);
+	bool long_hpd;
+	int ret;
+
+	mutex_lock(&dp->irq_lock);
+	long_hpd = dp->hotplug.long_hpd;
+	mutex_unlock(&dp->irq_lock);
+
+	dev_dbg(dp->dev, "[drm] Get hpd irq - %s\n", long_hpd ? "long" : "short");
+
+	if (!long_hpd) {
+		if (dw_dp_needs_link_retrain(dp)) {
+			ret = dw_dp_link_retrain(dp);
+			if (ret)
+				dev_warn(dp->dev, "Retrain link failed\n");
+		}
+	} else {
+		drm_helper_hpd_irq_event(dp->bridge.dev);
+	}
+}
+
+static void dw_dp_handle_hpd_event(struct dw_dp *dp)
+{
+	u32 value;
+
+	mutex_lock(&dp->irq_lock);
+	regmap_read(dp->regmap, DW_DP_HPD_STATUS, &value);
+
+	if (value & HPD_IRQ) {
+		dev_dbg(dp->dev, "IRQ from the HPD\n");
+		dp->hotplug.long_hpd = false;
+		regmap_write(dp->regmap, DW_DP_HPD_STATUS, HPD_IRQ);
+	}
+
+	if (value & HPD_HOT_PLUG) {
+		dev_dbg(dp->dev, "Hot plug detected\n");
+		dp->hotplug.long_hpd = true;
+		regmap_write(dp->regmap, DW_DP_HPD_STATUS, HPD_HOT_PLUG);
+	}
+
+	if (value & HPD_HOT_UNPLUG) {
+		dev_dbg(dp->dev, "Unplug detected\n");
+		dp->hotplug.long_hpd = true;
+		regmap_write(dp->regmap, DW_DP_HPD_STATUS, HPD_HOT_UNPLUG);
+	}
+	mutex_unlock(&dp->irq_lock);
+
+	schedule_work(&dp->hpd_work);
+}
+
+static irqreturn_t dw_dp_irq(int irq, void *data)
+{
+	struct dw_dp *dp = data;
+	u32 value;
+
+	regmap_read(dp->regmap, DW_DP_GENERAL_INTERRUPT, &value);
+	if (!value)
+		return IRQ_NONE;
+
+	if (value & HPD_EVENT)
+		dw_dp_handle_hpd_event(dp);
+
+	if (value & AUX_REPLY_EVENT) {
+		regmap_write(dp->regmap, DW_DP_GENERAL_INTERRUPT, AUX_REPLY_EVENT);
+		complete(&dp->complete);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static const struct regmap_range dw_dp_readable_ranges[] = {
+	regmap_reg_range(DW_DP_VERSION_NUMBER, DW_DP_ID),
+	regmap_reg_range(DW_DP_CONFIG_REG1, DW_DP_CONFIG_REG3),
+	regmap_reg_range(DW_DP_CCTL, DW_DP_SOFT_RESET_CTRL),
+	regmap_reg_range(DW_DP_VSAMPLE_CTRL, DW_DP_VIDEO_HBLANK_INTERVAL),
+	regmap_reg_range(DW_DP_AUD_CONFIG1, DW_DP_AUD_CONFIG1),
+	regmap_reg_range(DW_DP_SDP_VERTICAL_CTRL, DW_DP_SDP_STATUS_EN),
+	regmap_reg_range(DW_DP_PHYIF_CTRL, DW_DP_PHYIF_PWRDOWN_CTRL),
+	regmap_reg_range(DW_DP_AUX_CMD, DW_DP_AUX_DATA3),
+	regmap_reg_range(DW_DP_GENERAL_INTERRUPT, DW_DP_HPD_INTERRUPT_ENABLE),
+};
+
+static const struct regmap_access_table dw_dp_readable_table = {
+	.yes_ranges     = dw_dp_readable_ranges,
+	.n_yes_ranges   = ARRAY_SIZE(dw_dp_readable_ranges),
+};
+
+static const struct regmap_config dw_dp_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
+	.max_register = DW_DP_MAX_REGISTER,
+	.rd_table = &dw_dp_readable_table,
+};
+
+struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
+			 const struct dw_dp_plat_data *plat_data)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct dw_dp *dp;
+	struct drm_bridge *bridge;
+	void __iomem *res;
+	int ret;
+
+	dp = devm_kzalloc(dev, sizeof(*dp), GFP_KERNEL);
+	if (!dp)
+		return ERR_PTR(-ENOMEM);
+
+	dp->dev = dev;
+	dp->video.pixel_mode = DW_DP_MP_QUAD_PIXEL;
+
+	dp->plat_data = plat_data;
+	bridge = &dp->bridge;
+	mutex_init(&dp->irq_lock);
+	INIT_WORK(&dp->hpd_work, dw_dp_hpd_work);
+	init_completion(&dp->complete);
+
+	res = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(res))
+		return ERR_CAST(res);
+
+	dp->regmap = devm_regmap_init_mmio(dev, res, &dw_dp_regmap_config);
+	if (IS_ERR(dp->regmap)) {
+		dev_err_probe(dev, PTR_ERR(dp->regmap), "failed to create regmap\n");
+		return ERR_CAST(dp->regmap);
+	}
+
+	dp->phy = devm_of_phy_get(dev, dev->of_node, NULL);
+	if (IS_ERR(dp->phy)) {
+		dev_err_probe(dev, PTR_ERR(dp->phy), "failed to get phy\n");
+		return ERR_CAST(dp->phy);
+	}
+
+	dp->apb_clk = devm_clk_get_enabled(dev, "apb");
+	if (IS_ERR(dp->apb_clk)) {
+		dev_err_probe(dev, PTR_ERR(dp->apb_clk), "failed to get apb clock\n");
+		return ERR_CAST(dp->apb_clk);
+	}
+
+	dp->aux_clk = devm_clk_get_enabled(dev, "aux");
+	if (IS_ERR(dp->aux_clk)) {
+		dev_err_probe(dev, PTR_ERR(dp->aux_clk), "failed to get aux clock\n");
+		return ERR_CAST(dp->aux_clk);
+	}
+
+	dp->i2s_clk = devm_clk_get(dev, "i2s");
+	if (IS_ERR(dp->i2s_clk)) {
+		dev_err_probe(dev, PTR_ERR(dp->i2s_clk), "failed to get i2s clock\n");
+		return ERR_CAST(dp->i2s_clk);
+	}
+
+	dp->spdif_clk = devm_clk_get(dev, "spdif");
+	if (IS_ERR(dp->spdif_clk)) {
+		dev_err_probe(dev, PTR_ERR(dp->spdif_clk), "failed to get spdif clock\n");
+		return ERR_CAST(dp->spdif_clk);
+	}
+
+	dp->hdcp_clk = devm_clk_get(dev, "hdcp");
+	if (IS_ERR(dp->hdcp_clk)) {
+		dev_err_probe(dev, PTR_ERR(dp->hdcp_clk), "failed to get hdcp clock\n");
+		return ERR_CAST(dp->hdcp_clk);
+	}
+
+	dp->rstc = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(dp->rstc)) {
+		dev_err_probe(dev, PTR_ERR(dp->rstc), "failed to get reset control\n");
+		return ERR_CAST(dp->rstc);
+	}
+
+	dp->irq = platform_get_irq(pdev, 0);
+	if (dp->irq < 0)
+		return ERR_PTR(ret);
+
+	ret = devm_request_threaded_irq(dev, dp->irq, NULL, dw_dp_irq,
+					IRQF_ONESHOT, dev_name(dev), dp);
Are you ready to handle the IRQ here, before the bridge is filled?
I will move to  devm_request_threaded_irq after dw_dp_init_hw.

quoted
quoted
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to request irq\n");
+		return ERR_PTR(ret);
+	}
+
+	bridge->of_node = dev->of_node;
+	bridge->funcs = &dw_dp_bridge_funcs;
+	bridge->ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
+	bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
+	bridge->ycbcr_420_allowed = true;
+	bridge->vendor = "Synopsys";
+	bridge->product = "DW DP TX";
These two are unused
quoted
+
+	platform_set_drvdata(pdev, dp);
Unused
I will remove them.

Thanks again.

quoted
quoted
+
+	dp->aux.dev = dev;
+	dp->aux.drm_dev = encoder->dev;
+	dp->aux.name = dev_name(dev);
+	dp->aux.transfer = dw_dp_aux_transfer;
+	ret = drm_dp_aux_register(&dp->aux);
+	if (ret) {
+		dev_err_probe(dev, ret, "Aux register failed\n");
+		return ERR_PTR(ret);
+	}
+
+	ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+	if (ret)
+		dev_err_probe(dev, ret, "Failed to attach bridge\n");
+
+	dw_dp_init_hw(dp);
+
+	return dp;
+}
+MODULE_AUTHOR("Andy Yan [off-list ref]");
+MODULE_DESCRIPTION("DW DP Core Library");
+MODULE_LICENSE("GPL");
diff --git a/include/drm/bridge/dw_dp.h b/include/drm/bridge/dw_dp.h
new file mode 100644
index 000000000000..07845f609eca
--- /dev/null
+++ b/include/drm/bridge/dw_dp.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2025 Rockchip Electronics Co., Ltd.
+ */
+
+#ifndef __DW_DP__
+#define __DW_DP__
+
+struct device;
+struct drm_encoder;
+struct dw_dp;
+
+struct dw_dp_plat_data {
+	u32 max_link_rate;
+};
+
+struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
+			 const struct dw_dp_plat_data *plat_data);
+#endif /* __DW_DP__ */
-- 
2.34.1
-- 
With best wishes
Dmitry
-- 
With best wishes
Dmitry
-- 
With best wishes
Dmitry
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