Commit 11b31549 authored by Timur Kristóf's avatar Timur Kristóf Committed by Alex Deucher
Browse files

drm/amd/display: Disable 10-bit truncation and dithering on DCE 6.x 

DCE 6.x doesn't support 10-bit truncation and 10-bit dithering
because the following fields are 1-bit only:
FMT_TEMPORAL_DITHER_DEPTH
FMT_SPATIAL_DITHER_DEPTH
FMT_TRUNCATE_DEPTH
Programming these fields to "2" will program them as if the
dithering option was 6-bit, resulting in sub-par picture
quality and an ugly "color banding" effect.

Note that a recent commit changed the default 10-bit dithering
option to DITHER_OPTION_SPATIAL10 which improves the picture
quality because it happens to look better, but is still not
actually supported by DCE 6.x versions.

When the color depth is 10-bit or more, just disable
any kind of dithering options on DCE 6.x.

Closes: https://gitlab.freedesktop.org/drm/amd/-/work_items/5151


Fixes: 529cad0f ("drm/amd/display: Add function to set dither option")
Signed-off-by: default avatarTimur Kristóf <timur.kristof@gmail.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 6be8ced880dfe29ce38c2d5e74489822da5c250e)
parent 778bf584

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

+6 −0
Original line number Diff line number Diff line
@@ -5069,6 +5069,12 @@ void resource_build_bit_depth_reduction_params(struct dc_stream_state *stream, 
		}

	}



	if (stream->ctx->dce_version < DCE_VERSION_8_0 &&

	    stream->timing.display_color_depth >= COLOR_DEPTH_101010) {

		/* DCE 6.x doesn't support 10-bit truncation or dither options. */

		option = DITHER_OPTION_DISABLE;

	}



	if (option == DITHER_OPTION_DISABLE)

		return;