From: Josip Pavic Josip.Pavic@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.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 Signed-off-by: Sasha Levin sashal@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 11019c2c62cc..8192f1967e92 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c @@ -126,6 +126,12 @@ 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 15734db0cdea..f3c311d09319 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c @@ -531,6 +531,12 @@ static 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;