The patch below does not apply to the 5.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7344bad7fb6daa4877a1c064b52c7d5f9182c41b Mon Sep 17 00:00:00 2001 From: Jani Nikula jani.nikula@intel.com Date: Wed, 23 Mar 2022 12:04:38 +0200 Subject: [PATCH] drm/edid: fix CEA extension byte #3 parsing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Only an EDID CEA extension has byte #3, while the CTA DisplayID Data Block does not. Don't interpret bogus data for color formats.

For most displays it's probably an unlikely scenario you'd have a CTA DisplayID Data Block without a CEA extension, but they do exist.

Fixes: e28ad544f462 ("drm/edid: parse CEA blocks embedded in DisplayID") Cc: stable@vger.kernel.org Cc: Shawn C Lee shawn.c.lee@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20220323100438.1757295-1-jani....

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index f07af6786cec..cc7bd58369df 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -5188,10 +5188,14 @@ static void drm_parse_cea_ext(struct drm_connector *connector,

/* The existence of a CEA block should imply RGB support */ info->color_formats = DRM_COLOR_FORMAT_RGB444; - if (edid_ext[3] & EDID_CEA_YCRCB444) - info->color_formats |= DRM_COLOR_FORMAT_YCBCR444; - if (edid_ext[3] & EDID_CEA_YCRCB422) - info->color_formats |= DRM_COLOR_FORMAT_YCBCR422; + + /* CTA DisplayID Data Block does not have byte #3 */ + if (edid_ext[0] == CEA_EXT) { + if (edid_ext[3] & EDID_CEA_YCRCB444) + info->color_formats |= DRM_COLOR_FORMAT_YCBCR444; + if (edid_ext[3] & EDID_CEA_YCRCB422) + info->color_formats |= DRM_COLOR_FORMAT_YCBCR422; + }

if (cea_db_offsets(edid_ext, &start, &end)) return;