drm/amd/display: Fix ASSR regression on embedded panels

[Why]
Regression found in some embedded panels traces back to the earliest
upstreamed ASSR patch. The changed code flow are causing problems
with some panels.

[How]
- Change ASSR enabling code while preserving original code flow
  as much as possible
- Simplify the code on guarding with internal display flag

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=213779
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1620
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 12066f5..9fb8c46 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1820,8 +1820,7 @@ bool perform_link_training_with_retries(
                                         */
                                        panel_mode = DP_PANEL_MODE_DEFAULT;
                                }
-                       } else
-                               panel_mode = DP_PANEL_MODE_DEFAULT;
+                       }
                }
 #endif
 
@@ -4650,7 +4649,10 @@ enum dp_panel_mode dp_get_panel_mode(struct dc_link *link)
                }
        }
 
-       if (link->dpcd_caps.panel_mode_edp) {
+       if (link->dpcd_caps.panel_mode_edp &&
+               (link->connector_signal == SIGNAL_TYPE_EDP ||
+                (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT &&
+                 link->is_internal_display))) {
                return DP_PANEL_MODE_EDP;
        }