drm/amd/display: check TG is non-null before checking if enabled

[Why & How]
If there is no TG allocation we can dereference a NULL pointer when
checking if the TG is enabled.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alan Liu <haoping.liu@amd.com>
Signed-off-by: Taimur Hassan <syed.hassan@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index a503090..9834b75 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -3278,7 +3278,8 @@ void dcn10_wait_for_mpcc_disconnect(
                if (pipe_ctx->stream_res.opp->mpcc_disconnect_pending[mpcc_inst]) {
                        struct hubp *hubp = get_hubp_by_inst(res_pool, mpcc_inst);
 
-                       if (pipe_ctx->stream_res.tg->funcs->is_tg_enabled(pipe_ctx->stream_res.tg))
+                       if (pipe_ctx->stream_res.tg &&
+                               pipe_ctx->stream_res.tg->funcs->is_tg_enabled(pipe_ctx->stream_res.tg))
                                res_pool->mpc->funcs->wait_for_idle(res_pool->mpc, mpcc_inst);
                        pipe_ctx->stream_res.opp->mpcc_disconnect_pending[mpcc_inst] = false;
                        hubp->funcs->set_blank(hubp, true);