From 2d79805903bb7683411c071fd61791a95141cbf6 Mon Sep 17 00:00:00 2001
From: Cooper Chiou <cooper.chiou@intel.com>
Date: Thu, 24 Mar 2022 14:12:18 +0800
Subject: drm/edid: check basic audio support on CEA extension block
Git-commit: 5662abf6e21338be6d085d6375d3732ac6147fd2
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

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.

v3: update commit message.

Cc: stable@vger.kernel.org
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")
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220324061218.32739-1-shawn.c.lee@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 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");
-- 
2.38.1