On Wed, 23 Mar 2022, Lee Shawn C shawn.c.lee@intel.com wrote:

From: Cooper Chiou cooper.chiou@intel.com

Tag code stored in bit7:5 for CTA block byte[3] is not the same as CEA extension block definition. Only check CEA block has basic audio support.

Cc: Jani Nikula jani.nikula@intel.com Cc: Shawn C Lee shawn.c.lee@intel.com Cc: intel-gfx intel-gfx@lists.freedesktop.org Signed-off-by: Cooper Chiou cooper.chiou@intel.com Signed-off-by: Lee Shawn C shawn.c.lee@intel.com

Fixes: e28ad544f462 ("drm/edid: parse CEA blocks embedded in DisplayID") Cc: stable@vger.kernel.org # v4.15 Reviewed-by: Jani Nikula jani.nikula@intel.com

(commit e28ad544f462 was merged in v5.3, but it has Cc: stable for v4.15.)

Also drm_edid_to_eld() and drm_parse_cea_ext() are affected by the same issue. For the former, it doesn't really matter all that much, it just ends up using the DisplayID data block version instead, but the latter adds bogus color formats and should be fixed. Patch follows.

All of these are fixed in my recent series [1], but we'll want the simple fixes for stable first.

BR, Jani.

[1] https://patchwork.freedesktop.org/series/101659/

---

drivers/gpu/drm/drm_edid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 561f53831e29..f07af6786cec 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -4859,7 +4859,8 @@ bool drm_detect_monitor_audio(struct edid *edid) if (!edid_ext) goto end;

• has_audio = ((edid_ext[3] & EDID_BASIC_AUDIO) != 0);

• has_audio = (edid_ext[0] == CEA_EXT &&

•     (edid_ext[3] & EDID_BASIC_AUDIO) != 0);
  
  

  if (has_audio) { DRM_DEBUG_KMS("Monitor has basic audio support\n");