drm/amd/display: Fix Display Flicker on embedded panels

commit 083fa05bbaf65a01866b5440031c822e32ad7510 upstream.

[Why]
ASSR is dependent on Signed PSP Verstage to enable Content
Protection for eDP panels. Unsigned PSP verstage is used
during development phase causing ASSR to FAIL.
As a result, link training is performed with
DP_PANEL_MODE_DEFAULT instead of DP_PANEL_MODE_EDP for
eDP panels that causes display flicker on some panels.

[How]
- Do not change panel mode, if ASSR is disabled
- Just report and continue to perform eDP link training
with right settings further.

Signed-off-by: Praful Swarnakar <Praful.Swarnakar@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 83ef72a3ebf413688c4c2eabffe099d295fa0e90..3c8da3665a274c98ea8163b9abd0fd03945fa9cc 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
@@ -1813,14 +1813,13 @@ bool perform_link_training_with_retries(
                if (panel_mode == DP_PANEL_MODE_EDP) {
                        struct cp_psp *cp_psp = &stream->ctx->cp_psp;
 
-                       if (cp_psp && cp_psp->funcs.enable_assr) {
-                               if (!cp_psp->funcs.enable_assr(cp_psp->handle, link)) {
-                                       /* since eDP implies ASSR on, change panel
-                                        * mode to disable ASSR
-                                        */
-                                       panel_mode = DP_PANEL_MODE_DEFAULT;
-                               }
-                       }
+                       if (cp_psp && cp_psp->funcs.enable_assr)
+                               /* ASSR is bound to fail with unsigned PSP
+                                * verstage used during devlopment phase.
+                                * Report and continue with eDP panel mode to
+                                * perform eDP link training with right settings
+                                */
+                               cp_psp->funcs.enable_assr(cp_psp->handle, link);
                }
 #endif