[PATCH] drm/amd/display: Fix 10bit 4K display on CIK GPUs

Liviu Dudau liviu at dudau.co.uk
Wed Jul 14 08:06:52 UTC 2021

Commit 72a7cf0aec0c ("drm/amd/display: Keep linebuffer pixel depth at
30bpp for DCE-11.0.") doesn't seems to have fixed 10bit 4K rendering over
DisplayPort for CIK GPUs. On my machine with a HAWAII GPU I get a broken
image that looks like it has an effective resolution of 1920x1080 but
scaled up in an irregular way. Reverting the commit or applying this
patch fixes the problem on v5.14-rc1.

Fixes: 72a7cf0aec0c ("drm/amd/display: Keep linebuffer pixel depth at 30bpp for DCE-11.0.")
Signed-off-by: Liviu Dudau <liviu at dudau.co.uk>
 drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index a6a67244a322e..1596f6b7fed7c 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1062,7 +1062,7 @@ bool resource_build_scaling_params(struct pipe_ctx *pipe_ctx)
 	 * so use only 30 bpp on DCE_VERSION_11_0. Testing with DCE 11.2 and 8.3
 	 * did not show such problems, so this seems to be the exception.
-	if (plane_state->ctx->dce_version != DCE_VERSION_11_0)
+	if (plane_state->ctx->dce_version > DCE_VERSION_11_0)
 		pipe_ctx->plane_res.scl_data.lb_params.depth = LB_PIXEL_DEPTH_36BPP;
 		pipe_ctx->plane_res.scl_data.lb_params.depth = LB_PIXEL_DEPTH_30BPP;

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