From 18e551b2773b838509786b5f5beb2b7b0d254540 Mon Sep 17 00:00:00 2001
From: Aric Cyr <aric.cyr@amd.com>
Date: Mon, 11 Jul 2022 10:03:03 -0400
Subject: drm/amd/display: Avoid MPC infinite loop
Git-commit: 8de297dc046c180651c0500f8611663ae1c3828a
Patch-mainline: v6.0-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 jsc#PED-2849
[why]
In some cases MPC tree bottom pipe ends up point to itself. This causes
iterating from top to bottom to hang the system in an infinite loop.
[how]
When looping to next MPC bottom pipe, check that the pointer is not same
as current to avoid infinite loop.
Reviewed-by: Josip Pavic <Josip.Pavic@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
index 11019c2c62cc..769974375b4b 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
@@ -49,6 +49,11 @@ void mpc1_set_bg_color(struct mpc *mpc,
/* find bottommost mpcc. */
while (bottommost_mpcc->mpcc_bot) {
+ /* avoid circular linked link */
+ ASSERT(bottommost_mpcc != bottommost_mpcc->mpcc_bot);
+ if (bottommost_mpcc == bottommost_mpcc->mpcc_bot)
+ break;
+
bottommost_mpcc = bottommost_mpcc->mpcc_bot;
}
--
2.38.1