drm/amd/display: Add 3x4 CTM support for plane CTM

Create drm_color_ctm_3x4 to support 3x4-dimension plane CTM matrix and
convert DRM CTM to DC CSC float matrix.

v3:
- rename ctm2 to ctm_3x4 (Harry)
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c

@@ -434,6 +434,28 @@ static void __drm_ctm_to_dc_matrix(const struct drm_color_ctm *ctm,
 	}
 }
 
+/**
+ * __drm_ctm_3x4_to_dc_matrix - converts a DRM CTM 3x4 to a DC CSC float matrix
+ * @ctm: DRM color transformation matrix with 3x4 dimensions
+ * @matrix: DC CSC float matrix
+ *
+ * The matrix needs to be a 3x4 (12 entry) matrix.
+ */
+static void __drm_ctm_3x4_to_dc_matrix(const struct drm_color_ctm_3x4 *ctm,
+				       struct fixed31_32 *matrix)
+{
+	int i;
+
+	/* 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++) {
+		/* gamut_remap_matrix[i] = ctm[i - floor(i/4)] */
+		matrix[i] = dc_fixpt_from_s3132(ctm->matrix[i]);
+	}
+}
+
 /**
  * __set_legacy_tf - Calculates the legacy transfer function
  * @func: transfer function
@@ -1173,7 +1195,7 @@ int amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state *crtc,
 {
 	struct amdgpu_device *adev = drm_to_adev(crtc->base.state->dev);
 	struct dm_plane_state *dm_plane_state = to_dm_plane_state(plane_state);
-	struct drm_color_ctm *ctm = NULL;
+	struct drm_color_ctm_3x4 *ctm = NULL;
 	struct dc_color_caps *color_caps = NULL;
 	bool has_crtc_cm_degamma;
 	int ret;
@@ -1228,7 +1250,7 @@ int amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state *crtc,
 
 	/* Setup CRTC CTM. */
 	if (dm_plane_state->ctm) {
-		ctm = (struct drm_color_ctm *)dm_plane_state->ctm->data;
+		ctm = (struct drm_color_ctm_3x4 *)dm_plane_state->ctm->data;
 		/*
 		 * DCN2 and older don't support both pre-blending and
 		 * post-blending gamut remap. For this HW family, if we have
@@ -1240,7 +1262,7 @@ int amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state *crtc,
 		 * mapping CRTC CTM to MPC and keeping plane CTM setup at DPP,
 		 * as it's done by dcn30_program_gamut_remap().
 		 */
-		__drm_ctm_to_dc_matrix(ctm, dc_plane_state->gamut_remap_matrix.matrix);
+		__drm_ctm_3x4_to_dc_matrix(ctm, dc_plane_state->gamut_remap_matrix.matrix);
 
 		dc_plane_state->gamut_remap_matrix.enable_remap = true;
 		dc_plane_state->input_csc_color_matrix.enable_adjustment = false;

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c

@@ -1561,7 +1561,7 @@ dm_atomic_plane_set_property(struct drm_plane *plane,
 		ret = drm_property_replace_blob_from_id(plane->dev,
 							&dm_plane_state->ctm,
 							val,
-							sizeof(struct drm_color_ctm), -1,
+							sizeof(struct drm_color_ctm_3x4), -1,
 							&replaced);
 		dm_plane_state->base.color_mgmt_changed |= replaced;
 		return ret;

include/uapi/drm/drm_mode.h

@@ -846,6 +846,14 @@ struct drm_color_ctm {
 	__u64 matrix[9];
 };
 
+struct drm_color_ctm_3x4 {
+	/*
+	 * Conversion matrix with 3x4 dimensions in S31.32 sign-magnitude
+	 * (not two's complement!) format.
+	 */
+	__u64 matrix[12];
+};
+
 struct drm_color_lut {
 	/*
 	 * Values are mapped linearly to 0.0 - 1.0 range, with 0x0 == 0.0 and