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drm/amd/display: Reject overlay plane configurations in multi-display scenarios 

[ Upstream commit 168f09cdad ]

[Why]
These aren't stable on some platform configurations when driving
multiple displays, especially on higher resolution.

In particular the delay in asserting p-state and validating from
x86 outweights any power or performance benefit from the hardware
composition.

Under some configurations this will manifest itself as extreme stutter
or unresponsiveness especially when combined with cursor movement.

[How]
Disable these for now. Exposing overlays to userspace doesn't guarantee
that they'll be able to use them in any and all configurations and it's
part of the DRM contract to have userspace gracefully handle validation
failures when they occur.

Valdiation occurs as part of DC and this in particular affects RV, so
disable this in dcn10_global_validation.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Nicholas Kazlauskas 2020-08-19 13:37:54 -04:00 committed by Greg Kroah-Hartman
parent 29bade8e2f
commit 79d31527df
1 changed files with 8 additions and 0 deletions
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8
drivers/gpu/drm/amd/display/dc/dcn10/dcn10_resource.c
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@ -1151,6 +1151,7 @@ static enum dc_status dcn10_validate_global(struct dc *dc, struct dc_state *cont
bool video_large = false;
bool desktop_large = false;
bool dcc_disabled = false;
bool mpo_enabled = false;
for (i = 0; i < context->stream_count; i++) {
if (context->stream_status[i].plane_count == 0)
@ -1159,6 +1160,9 @@ static enum dc_status dcn10_validate_global(struct dc *dc, struct dc_state *cont
if (context->stream_status[i].plane_count > 2)
return DC_FAIL_UNSUPPORTED_1;
if (context->stream_status[i].plane_count > 1)
mpo_enabled = true;
for (j = 0; j < context->stream_status[i].plane_count; j++) {
struct dc_plane_state *plane =
context->stream_status[i].plane_states[j];
@ -1182,6 +1186,10 @@ static enum dc_status dcn10_validate_global(struct dc *dc, struct dc_state *cont
}
}
/* Disable MPO in multi-display configurations. */
if (context->stream_count > 1 && mpo_enabled)
return DC_FAIL_UNSUPPORTED_1;
/*
* Workaround: On DCN10 there is UMC issue that causes underflow when
* playing 4k video on 4k desktop with video downscaled and single channel