From: Josip Pavic <josip.pa...@amd.com> [ Upstream commit 8de297dc046c180651c0500f8611663ae1c3828a ]
[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> Tested-by: Daniel Wheeler <daniel.whee...@amd.com> Signed-off-by: Alex Deucher <alexander.deuc...@amd.com> Signed-off-by: Sasha Levin <sas...@kernel.org> --- drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c | 6 ++++++ drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c | 6 ++++++ 2 files changed, 12 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 3fcd408e9103..855682590c1b 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c @@ -125,6 +125,12 @@ struct mpcc *mpc1_get_mpcc_for_dpp(struct mpc_tree *tree, int dpp_id) while (tmp_mpcc != NULL) { if (tmp_mpcc->dpp_id == dpp_id) return tmp_mpcc; + + /* avoid circular linked list */ + ASSERT(tmp_mpcc != tmp_mpcc->mpcc_bot); + if (tmp_mpcc == tmp_mpcc->mpcc_bot) + break; + tmp_mpcc = tmp_mpcc->mpcc_bot; } return NULL; diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c index 99cc095dc33c..a701ea56c0aa 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c @@ -533,6 +533,12 @@ struct mpcc *mpc2_get_mpcc_for_dpp(struct mpc_tree *tree, int dpp_id) while (tmp_mpcc != NULL) { if (tmp_mpcc->dpp_id == 0xf || tmp_mpcc->dpp_id == dpp_id) return tmp_mpcc; + + /* avoid circular linked list */ + ASSERT(tmp_mpcc != tmp_mpcc->mpcc_bot); + if (tmp_mpcc == tmp_mpcc->mpcc_bot) + break; + tmp_mpcc = tmp_mpcc->mpcc_bot; } return NULL; -- 2.35.1