From 8e686f8fd289d0bc2f4e2f1cc06eef3fc65d070a Mon Sep 17 00:00:00 2001 From: "Leo (Sunpeng) Li" Date: Fri, 23 Feb 2018 12:59:03 -0500 Subject: [PATCH 3748/4131] drm/amd/display: Convert CTM to 2's complement DRM's documentation for the color transform matrix does not specify whether the values are in signed-magnitude, or 2's complement. Therefore, it was assumed to use 2's complement. However, existing usermode implementations use signed-magnitude. Therefore, conform to existing standards, and convert to 2's complement internally. Signed-off-by: Leo (Sunpeng) Li Reviewed-by: Harry Wentland --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c index e845c51..f6cb502 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c @@ -193,6 +193,7 @@ void amdgpu_dm_set_ctm(struct dm_crtc_state *crtc) struct drm_property_blob *blob = crtc->base.ctm; struct dc_stream_state *stream = crtc->stream; struct drm_color_ctm *ctm; + int64_t val; int i; if (!blob) { @@ -206,7 +207,9 @@ void amdgpu_dm_set_ctm(struct dm_crtc_state *crtc) * DRM gives a 3x3 matrix, but DC wants 3x4. Assuming we're operating * with homogeneous coordinates, augment the matrix with 0's. * - * The format provided is S31.32, which is the same as our fixed31_32. + * The format provided is S31.32, using signed-magnitude representation. + * Our fixed31_32 is also S31.32, but is using 2's complement. We have + * to convert from signed-magnitude to 2's complement. */ for (i = 0; i < 12; i++) { /* Skip 4th element */ @@ -214,8 +217,14 @@ void amdgpu_dm_set_ctm(struct dm_crtc_state *crtc) stream->gamut_remap_matrix.matrix[i] = dal_fixed31_32_zero; continue; } - /* csc[i] = ctm[i - floor(i/4)] */ - stream->gamut_remap_matrix.matrix[i].value = ctm->matrix[i - (i/4)]; + + /* gamut_remap_matrix[i] = ctm[i - floor(i/4)] */ + val = ctm->matrix[i - (i/4)]; + /* If negative, convert to 2's complement. */ + if (val & (1ULL << 63)) + val = -(val & ~(1ULL << 63)); + + stream->gamut_remap_matrix.matrix[i].value = val; } } -- 2.7.4