[PATCH 6.4 369/800] drm/amd/display: Fix artifacting on eDP panels when engaging freesync video mode

Greg Kroah-Hartman
2023-07-16T20:10:08Z

From: Aurabindo Pillai <aurabindo.pillai@amd.com>

[ Upstream commit b18f05a0666aecd5cb19c26a8305bcfa4e9d6502 ]

[Why]
When freesync video mode is enabled, switching resolution from native
mode to one of the freesync video compatible modes can trigger continous
artifacts on some eDP panels when running under KDE. The articating can be seen in the
attached bug report.

[How]
Fix this by restricting updates that require full commit by using the same checks
for stream and scaling changes in the the enable pass of dm_update_crtc_state()
along with the check for compatible timings for freesync vide mode.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/2162
Fixes: da5e14909776 ("drm/amd/display: Fix hang when skipping modeset")
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -9259,6 +9259,8 @@ static int dm_update_crtc_state(struct a

/* Now check if we should set freesync video mode */
if (amdgpu_freesync_vid_mode && dm_new_crtc_state->stream &&
+ dc_is_stream_unchanged(new_stream, dm_old_crtc_state->stream) &&
+ dc_is_stream_scaling_unchanged(new_stream, dm_old_crtc_state->stream) &&
is_timing_unchanged_for_freesync(new_crtc_state,
old_crtc_state)) {
new_crtc_state->mode_changed = false;