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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 <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Leo (Sunpeng) Li 2018-02-23 12:59:03 -05:00 committed by Alex Deucher
parent a7596f25db
commit 5e3e341cee
1 changed files with 12 additions and 3 deletions
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15
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
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@ -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;
}
}