[Letux-kernel] [PATCH v16 4/4] drm/bridge: dw-hdmi: fix bus formats negotiation for 8 bit modes

H. Nikolaus Schaller hns at goldelico.com
Tue Mar 1 21:37:20 CET 2022


Hi Neil,


> Am 01.03.2022 um 10:18 schrieb Neil Armstrong <narmstrong at baylibre.com>:
> 
> Hi,
> 
> On 26/02/2022 18:13, H. Nikolaus Schaller wrote:
>> Commit 7cd70656d1285b ("drm/bridge: display-connector: implement bus fmts callbacks")
>> introduced a new mechanism to negotiate bus formats between hdmi connectors
>> and bridges which is to be used e.g. for the jz4780 based CI20 board.
>> In this case dw-hdmi sets up a list of formats in
>> dw_hdmi_bridge_atomic_get_output_bus_fmts().
>> This includes e.g. MEDIA_BUS_FMT_UYVY8_1X16 which is chosen for the CI20 but
>> only produces a black screen.
>> Analysis revealed an omission in
>> Commit 6c3c719936dafe ("drm/bridge: synopsys: dw-hdmi: add bus format negociation")
>> to check for 8 bit with when adding UYVY8 or YUV8 formats.
>> This fix is based on the observation that max_bpc = 0 when running this
>> function while info->bpc = 8.
> 
> In fact if bpc = 0, it should be considered as 8, so the issue is elsewhere.
> 
>> Adding the proposed patch makes the jz4780/CI20 panel work again with default
>> MEDIA_BUS_FMT_RGB888_1X24 mode.
>> Fixes: 7cd70656d1285b ("drm/bridge: display-connector: implement bus fmts callbacks")
>> Fixes: 6c3c719936dafe ("drm/bridge: synopsys: dw-hdmi: add bus format negociation")
>> Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
>> ---
>>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> index 43e375da131e8..c08e2cc96584c 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> @@ -2621,11 +2621,13 @@ static u32 *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
>>  		output_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
>>  	}
>>  -	if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
>> -		output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
>> +	if (max_bpc >= 8 && info->bpc >= 8) {
>> +		if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
>> +			output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
>>  -	if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
>> -		output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
>> +		if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
>> +			output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
>> +	}
> 
> It should not select YUV here if it's not possible, so something is wrong.
> 
> Can you check if https://lore.kernel.org/r/20220119123656.1456355-2-narmstrong@baylibre.com fixes this issue instead ?

Well, I had to manually fix it to be appliable to drm-misc/drm-misc-next
and specifically:

c03d0b52ff71 ("drm/connector: Fix typo in output format")

My resulting patch is attached.

Unfortunately it did not work.

I added a printk for hdmi->sink_is_hdmi. This returns 1. Which IMHO is to be expected
since I am using a HDMI connector and panel... So your patch will still add the UYVY formats.

Either the synposys module inside the jz4780 or the panel does not understand them.

Here is the EDID. Unfortunately it does not pretty print the extended descriptors for UYVY etc.
so that I don't know the exact capabilities of the panel. And what I am not sure is if the
jz4780 SoC can convert to UYVY or how it can.

root at letux:~# parse-edid </sys/devices/platform/13050000.lcdc0/drm/card0/card0-HDMI-A-1/edid
Checksum Correct

Section "Monitor"
        Identifier "LEN L1950wD"
        ModelName "LEN L1950wD"
        VendorName "LEN"
        # Monitor Manufactured week 34 of 2011
        # EDID version 1.3
        # Digital Display
        DisplaySize 410 260
        Gamma 2.20
        Option "DPMS" "true"
        Horizsync 30-81
        VertRefresh 50-76
        # Maximum pixel clock is 140MHz
        #Not giving standard mode: 1152x864, 75Hz
        #Not giving standard mode: 1280x720, 60Hz
        #Not giving standard mode: 1280x1024, 60Hz
        #Not giving standard mode: 1280x1024, 60Hz
        #Not giving standard mode: 1280x1024, 60Hz
        #Not giving standard mode: 1440x900, 60Hz
        #Not giving standard mode: 1440x900, 75Hz
        #Not giving standard mode: 1920x1080, 60Hz

        #Extension block found. Parsing...
        Modeline        "Mode 15" -hsync -vsync 
        Modeline        "Mode 0" -hsync +vsync 
        Modeline        "Mode 1" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
        Modeline        "Mode 2" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
        Modeline        "Mode 3" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
        Modeline        "Mode 4" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
        Modeline        "Mode 5" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
        Modeline        "Mode 6" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
        Modeline        "Mode 7" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
        Modeline        "Mode 8" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
        Modeline        "Mode 9" 74.250 1280 1720 1760 1980 720 725 730 750 +hsync +vsync
        Modeline        "Mode 10" 74.250 1280 1390 1420 1650 720 725 730 750 +hsync +vsync
        Modeline        "Mode 11" 74.250 1920 2448 2492 2640 1080 1082 1089 1125 +hsync +vsync interlace
        Modeline        "Mode 12" 74.250 1920 2008 2052 2200 1080 1082 1087 1125 +hsync +vsync interlace
        Modeline        "Mode 13" 148.500 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
        Modeline        "Mode 14" 148.500 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
        Modeline        "Mode 16" +hsync +vsync interlace
        Modeline        "Mode 17" +hsync +vsync interlace
        Modeline        "Mode 18" +hsync +vsync 
        Option "PreferredMode" "Mode 15"
EndSection
root at letux:~# xxd /sys/devices/platform/13050000.lcdc0/drm/card0/card0-HDMI-A-1/ 
00000000: 00ff ffff ffff ff00 30ae 8610 0101 0101  ........0.......
00000010: 2215 0103 8029 1a78 eee5 b5a3 5549 9927  "....).x....UI.'
00000020: 1350 54af ef00 714f 81c0 8180 8180 8180  .PT...qO........
00000030: 9500 950f d1c0 2413 0020 4158 1620 050d  ......$.. AX. ..
00000040: 2300 ffff 0000 001c 0000 00fc 004c 454e  #............LEN
00000050: 204c 3139 3530 7744 0a20 0000 00fd 0032   L1950wD. .....2
00000060: 4c1e 510e 000a 2020 2020 2020 0000 00ff  L.Q...      ....
00000070: 0042 3334 3332 3834 350a 2020 2020 0101  .B3432845.    ..
00000080: 0203 2171 4e06 0702 0315 9611 1213 0414  ..!qN...........
00000090: 051f 9023 0907 0783 0100 0065 030c 0010  ...#.......e....
000000a0: 008c 0ad0 9020 4031 200c 4055 00b9 8821  ..... @1 . at U...!
000000b0: 0000 1801 1d80 1871 1c16 2058 2c25 00b9  .......q.. X,%..
000000c0: 8821 0000 9e01 1d80 d072 1c16 2010 2c25  .!.......r.. .,%
000000d0: 80b9 8821 0000 9e01 1d00 bc52 d01e 20b8  ...!.......R.. .
000000e0: 2855 40b9 8821 0000 1e02 3a80 d072 382d  (U at ..!....:..r8-
000000f0: 4010 2c45 80b9 8821 0000 1e00 0000 00d0  @.,E...!........
root at letux:~# root at letux:~# dmesg|grep dw.hdmi
[    9.622138] dw-hdmi-ingenic 10180000.hdmi: Detected HDMI TX controller v1.31a with HDCP (DWC HDMI 3D TX PHY)
[    9.727840] dw-hdmi-ingenic 10180000.hdmi: registered DesignWare HDMI I2C bus driver
[   10.103864] dw_hdmi_bridge_atomic_get_output_bus_fmts: hdmi->sink_is_hdmi=1

So please let me know which parameters I should try to printk()...

BR and thanks,
Nikolaus


------

From c84a3c4a500684e57b1243fe5386696c48fa1e1b Mon Sep 17 00:00:00 2001
From: Neil Armstrong <narmstrong at baylibre.com>
Date: Wed, 19 Jan 2022 13:36:56 +0100
Subject: [PATCH] drm/bridge: dw-hdmi: filter out YUV output formats when DVI

When the display is not an HDMI sink, only the RGB output format is
valid. Thus stop returning YUV output formats when sink is not HDMI.

Fixes: 6c3c719936da ("drm/bridge: synopsys: dw-hdmi: add bus format negociation")
Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 43e375da131e8..0ec0cbe448e05 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2538,6 +2538,7 @@ static u32 *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
        struct drm_connector *conn = conn_state->connector;
        struct drm_display_info *info = &conn->display_info;
        struct drm_display_mode *mode = &crtc_state->mode;
+       struct dw_hdmi *hdmi = bridge->driver_private;
        u8 max_bpc = conn_state->max_requested_bpc;
        bool is_hdmi2_sink = info->hdmi.scdc.supported ||
                             (info->color_formats & DRM_COLOR_FORMAT_YCBCR420);
@@ -2564,7 +2565,7 @@ static u32 *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
         * If the current mode enforces 4:2:0, force the output but format
         * to 4:2:0 and do not add the YUV422/444/RGB formats
         */
-       if (conn->ycbcr_420_allowed &&
+       if (hdmi->sink_is_hdmi && conn->ycbcr_420_allowed &&
            (drm_mode_is_420_only(info, mode) ||
             (is_hdmi2_sink && drm_mode_is_420_also(info, mode)))) {
 
@@ -2595,36 +2596,36 @@ static u32 *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
         */
 
        if (max_bpc >= 16 && info->bpc == 16) {
-               if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
+               if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
                        output_fmts[i++] = MEDIA_BUS_FMT_YUV16_1X48;
 
                output_fmts[i++] = MEDIA_BUS_FMT_RGB161616_1X48;
        }
 
        if (max_bpc >= 12 && info->bpc >= 12) {
-               if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
+               if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
                        output_fmts[i++] = MEDIA_BUS_FMT_UYVY12_1X24;
 
-               if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
+               if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
                        output_fmts[i++] = MEDIA_BUS_FMT_YUV12_1X36;
 
                output_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
        }
 
        if (max_bpc >= 10 && info->bpc >= 10) {
-               if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
+               if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
                        output_fmts[i++] = MEDIA_BUS_FMT_UYVY10_1X20;
 
-               if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
+               if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
                        output_fmts[i++] = MEDIA_BUS_FMT_YUV10_1X30;
 
                output_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
        }
 
-       if (info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
+       if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR422)
                output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
 
-       if (info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
+       if (hdmi->sink_is_hdmi && info->color_formats & DRM_COLOR_FORMAT_YCBCR444)
                output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
 
        /* Default 8bit RGB fallback */
-- 
2.33.0




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