[PATCH 5.14 069/172] drm/amd/display: Fix Display Flicker on embedded panels

Greg Kroah-Hartman
2021-10-04T13:32:55Z

From: Praful Swarnakar <Praful.Swarnakar@amd.com>

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>
---
drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

--- 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