From: Aric Cyr <aric....@amd.com>

[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.pa...@amd.com>
Reviewed-by: Jun Lei <jun....@amd.com>
Acked-by: Alex Hung <alex.h...@amd.com>
Signed-off-by: Aric Cyr <aric....@amd.com>
---
 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;
        }
 
-- 
2.37.1

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