From 63ad5371cd1e379519395c49a4b6a652c36c98e5 Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Wed, 5 Jan 2022 12:48:16 -0600
Subject: [PATCH] drm/amd/display: explicitly set is_dsc_supported to false before use
Git-commit: 63ad5371cd1e379519395c49a4b6a652c36c98e5
Patch-mainline: v5.17-rc1
References: git-fixes

When UBSAN is enabled a case is shown on unplugging the display that
this variable hasn't been initialized by `update_dsc_caps`, presumably
when the display was unplugged it wasn't copied from the DPCD.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1956497
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -5637,6 +5637,7 @@ static void update_dsc_caps(struct amdgp
 							struct dsc_dec_dpcd_caps *dsc_caps)
 {
 	stream->timing.flags.DSC = 0;
+	dsc_caps->is_dsc_supported = false;
 
 	if (aconnector->dc_link && sink->sink_signal == SIGNAL_TYPE_DISPLAY_PORT) {
 		dc_dsc_parse_dsc_dpcd(aconnector->dc_link->ctx->dc,