linux (RPi): add patch to fix color format check in vc4_hdmi

This fixes "no video" issue when working around EDID problems with
eg video=... kernel command line parameter.

Signed-off-by: Matthias Reichl <hias@horus.com>

packages/linux/patches/raspberrypi/linux-010-fix-vc4-rgb-check.patch

@@ -0,0 +1,41 @@
+From affc6fdac5376701ea468270af1b6fd9ca7616be Mon Sep 17 00:00:00 2001
+From: Matthias Reichl <hias@horus.com>
+Date: Sat, 11 Mar 2023 22:41:17 +0100
+Subject: [PATCH] drm/vc4: drop unnecessary and harmful HDMI RGB format check
+
+RGB is a mandatory format for all DVI and HDMI monitors so there's
+no need to check for presence of the DRM_COLOR_FORMAT_RGB444 bit in
+color_formats.
+
+More importantly this checks breaks working around EDID issues with
+eg video=HDMI-A-1:1024x768D or drm.edid_firmware=edid/1024x768.bin
+as the RGB444 bit is only set when a valid EDID with digital bit set in
+the input byte is present - which isn't the case when no EDID can be
+read from the display device at all or with the in-built kernel EDIDs,
+which mimic analog (VGA) displays without the digital bit set.
+
+So drop the check, if we output video on the HDMI connector we can
+assume that the display can accept 8bit RGB.
+
+Signed-off-by: Matthias Reichl <hias@horus.com>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi.c | 3 ---
+ 1 file changed, 3 deletions(-)
+
+diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
+index bd762b4e3e8f2..3c60c93c0f888 100644
+--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
+@@ -1962,9 +1962,6 @@ vc4_hdmi_sink_supports_format_bpc(const struct vc4_hdmi *vc4_hdmi,
+ 	case VC4_HDMI_OUTPUT_RGB:
+ 		drm_dbg(dev, "RGB Format, checking the constraints.\n");
+ 
+-		if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
+-			return false;
+-
+ 		if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
+ 			drm_dbg(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
+ 			return false;
+-- 
+2.39.2
+