[RFC PATCH v2 3/9] drm/vkms: Add CSC FF colorop to color pipeline

[Harry Wentland <harry.wentland@amd.com>]

Insert a CSC Fixed-Function colorop as the first operation in the
VKMS color pipeline, before the existing 1D curve. This allows
userspace to select YUV-to-RGB conversion via the color pipeline
for YCbCr framebuffers.

The CSC FF colorop advertises support for all six YUV-to-RGB
conversion presets:
  - YUV601/709/2020 full-range to RGB
  - YUV601/709/2020 limited-range to RGB

Bump MAX_COLOR_PIPELINE_OPS from 4 to 5 to accommodate the new op.

Assisted-by Claude:claude-opus-4.6

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
---
 drivers/gpu/drm/vkms/vkms_colorop.c | 66 ++++++++++++++++++++---------
 1 file changed, 46 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_colorop.c b/drivers/gpu/drm/vkms/vkms_colorop.c
index 071f3a8d2e7c..fa78ac7be36e 100644
--- a/drivers/gpu/drm/vkms/vkms_colorop.c
+++ b/drivers/gpu/drm/vkms/vkms_colorop.c
@@ -12,11 +12,19 @@ static const u64 supported_tfs =
 	BIT(DRM_COLOROP_1D_CURVE_SRGB_EOTF) |
 	BIT(DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF);
 
+static const u64 supported_csc_ff =
+	BIT(DRM_COLOROP_CSC_FF_YUV601_RGB601) |
+	BIT(DRM_COLOROP_CSC_FF_YUV601_LIMITED_RGB601) |
+	BIT(DRM_COLOROP_CSC_FF_YUV709_RGB709) |
+	BIT(DRM_COLOROP_CSC_FF_YUV709_LIMITED_RGB709) |
+	BIT(DRM_COLOROP_CSC_FF_YUV2020_RGB2020) |
+	BIT(DRM_COLOROP_CSC_FF_YUV2020_LIMITED_RGB2020);
+
 static const struct drm_colorop_funcs vkms_colorop_funcs = {
 	.destroy = drm_colorop_destroy,
 };
 
-#define MAX_COLOR_PIPELINE_OPS 4
+#define MAX_COLOR_PIPELINE_OPS 5
 
 static int vkms_initialize_color_pipeline(struct drm_plane *plane, struct drm_prop_enum_list *list)
 {
@@ -27,7 +35,25 @@ static int vkms_initialize_color_pipeline(struct drm_plane *plane, struct drm_pr
 
 	memset(ops, 0, sizeof(ops));
 
-	/* 1st op: 1d curve */
+	/* 1st op: CSC Fixed-Function (YUV to RGB) */
+	ops[i] = kzalloc_obj(*ops[i]);
+	if (!ops[i]) {
+		drm_err(dev, "KMS: Failed to allocate colorop\n");
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	ret = drm_plane_colorop_csc_ff_init(dev, ops[i], plane, &vkms_colorop_funcs,
+					    supported_csc_ff,
+					    DRM_COLOROP_FLAG_ALLOW_BYPASS);
+	if (ret)
+		goto cleanup;
+
+	list->type = ops[i]->base.id;
+
+	i++;
+
+	/* 2nd op: 1d curve */
 	ops[i] = kzalloc_obj(*ops[i]);
 	if (!ops[i]) {
 		drm_err(dev, "KMS: Failed to allocate colorop\n");
@@ -41,23 +67,6 @@ static int vkms_initialize_color_pipeline(struct drm_plane *plane, struct drm_pr
 	if (ret)
 		goto cleanup;
 
-	list->type = ops[i]->base.id;
-
-	i++;
-
-	/* 2nd op: 3x4 matrix */
-	ops[i] = kzalloc_obj(*ops[i]);
-	if (!ops[i]) {
-		drm_err(dev, "KMS: Failed to allocate colorop\n");
-		ret = -ENOMEM;
-		goto cleanup;
-	}
-
-	ret = drm_plane_colorop_ctm_3x4_init(dev, ops[i], plane, &vkms_colorop_funcs,
-					     DRM_COLOROP_FLAG_ALLOW_BYPASS);
-	if (ret)
-		goto cleanup;
-
 	drm_colorop_set_next_property(ops[i - 1], ops[i]);
 
 	i++;
@@ -79,7 +88,24 @@ static int vkms_initialize_color_pipeline(struct drm_plane *plane, struct drm_pr
 
 	i++;
 
-	/* 4th op: 1d curve */
+	/* 4th op: 3x4 matrix */
+	ops[i] = kzalloc_obj(*ops[i]);
+	if (!ops[i]) {
+		drm_err(dev, "KMS: Failed to allocate colorop\n");
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	ret = drm_plane_colorop_ctm_3x4_init(dev, ops[i], plane, &vkms_colorop_funcs,
+					     DRM_COLOROP_FLAG_ALLOW_BYPASS);
+	if (ret)
+		goto cleanup;
+
+	drm_colorop_set_next_property(ops[i - 1], ops[i]);
+
+	i++;
+
+	/* 5th op: 1d curve */
 	ops[i] = kzalloc_obj(*ops[i]);
 	if (!ops[i]) {
 		drm_err(dev, "KMS: Failed to allocate colorop\n");
-- 
2.53.0