[RESEND PATCH] drm/amd/display: Fix ASSR regression on embedded panels

[RESEND PATCH] drm/amd/display: Fix ASSR regression on embedded panels

[Alex Deucher]

From: Stylon Wang <stylon.wang@amd.com>

[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
(cherry picked from commit 6be50f5d83adc9541de3d5be26e968182b5ac150)
---

This is a backport of this patch to 5.13.  I originally sent this
out as a follow up to the reply that the original patch failed to
apply to 5.13, but it hasn't been applied yet.  Resending to make
sure it didn't get lost.

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 3 ---
 1 file changed, 3 deletions(-)

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 ae6830ff1cf7..774e825e5aab 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1675,9 +1675,6 @@ static enum dp_panel_mode try_enable_assr(struct dc_stream_state *stream)
 	} else
 		panel_mode = DP_PANEL_MODE_DEFAULT;
 
-#else
-	/* turn off ASSR if the implementation is not compiled in */
-	panel_mode = DP_PANEL_MODE_DEFAULT;
 #endif
 	return panel_mode;
 }
-- 
2.31.1

Re: [RESEND PATCH] drm/amd/display: Fix ASSR regression on embedded panels

[Greg KH]

On Wed, Aug 04, 2021 at 12:44:43PM -0400, Alex Deucher wrote:
> From: Stylon Wang <stylon.wang@amd.com>
> 
> [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
> (cherry picked from commit 6be50f5d83adc9541de3d5be26e968182b5ac150)
> ---
> 
> This is a backport of this patch to 5.13.  I originally sent this
> out as a follow up to the reply that the original patch failed to
> apply to 5.13, but it hasn't been applied yet.  Resending to make
> sure it didn't get lost.

Not lost, just not caught up on yet.  Now queued up, thanks.

greg k-h