[RFC PATCH v3 21/23] drm/vkms: add 3x4 matrix in color pipeline

[Harry Wentland]

We add two 3x4 matrices into the VKMS color pipeline. The reason
we're adding matrices is so that we can test that application
of a matrix and its inverse yields an output equal to the input
image.

One complication with the matrix implementation has to do with
the fact that the matrix entries are in signed-magnitude fixed
point, whereas the drm_fixed.h implementation uses 2s-complement.
The latter one is the one that we want for easy addition and
subtraction, so we convert all entries to 2s-complement.

Signed-off-by: Harry Wentland <harry.wentland at amd.com>
---
 drivers/gpu/drm/vkms/vkms_colorop.c  | 32 +++++++++++++++++++++++++++-
 drivers/gpu/drm/vkms/vkms_composer.c | 27 +++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vkms/vkms_colorop.c b/drivers/gpu/drm/vkms/vkms_colorop.c
index 9a26b9fdc4a2..4e37e805c443 100644
--- a/drivers/gpu/drm/vkms/vkms_colorop.c
+++ b/drivers/gpu/drm/vkms/vkms_colorop.c
@@ -31,7 +31,37 @@ const int vkms_initialize_tf_pipeline(struct drm_plane *plane, struct drm_prop_e
 
 	prev_op = op;
 
-	/* 2nd op: 1d curve */
+	/* 2nd op: 3x4 matrix */
+	op = kzalloc(sizeof(struct drm_colorop), GFP_KERNEL);
+	if (!op) {
+		DRM_ERROR("KMS: Failed to allocate colorop\n");
+		return -ENOMEM;
+	}
+
+	ret = drm_colorop_init(dev, op, plane, DRM_COLOROP_CTM_3X4);
+	if (ret)
+		return ret;
+
+	drm_colorop_set_next_property(prev_op, op);
+
+	prev_op = op;
+
+	/* 3rd op: 3x4 matrix */
+	op = kzalloc(sizeof(struct drm_colorop), GFP_KERNEL);
+	if (!op) {
+		DRM_ERROR("KMS: Failed to allocate colorop\n");
+		return -ENOMEM;
+	}
+
+	ret = drm_colorop_init(dev, op, plane, DRM_COLOROP_CTM_3X4);
+	if (ret)
+		return ret;
+
+	drm_colorop_set_next_property(prev_op, op);
+
+	prev_op = op;
+
+	/* 4th op: 1d curve */
 	op = kzalloc(sizeof(struct drm_colorop), GFP_KERNEL);
 	if (!op) {
 		DRM_ERROR("KMS: Failed to allocate colorop\n");
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index d04a235b9fcd..c278fb223188 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -164,6 +164,30 @@ static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buff
 	}
 }
 
+static void apply_3x4_matrix(struct pixel_argb_s32 *pixel, const struct drm_color_ctm_3x4 *matrix)
+{
+	s64 rf, gf, bf;
+
+	rf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[0]), drm_int2fixp(pixel->r)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[1]), drm_int2fixp(pixel->g)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[2]), drm_int2fixp(pixel->b)) +
+	     drm_sm2fixp(matrix->matrix[3]);
+
+	gf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[4]), drm_int2fixp(pixel->r)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[5]), drm_int2fixp(pixel->g)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[6]), drm_int2fixp(pixel->b)) +
+	     drm_sm2fixp(matrix->matrix[7]);
+
+	bf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[8]), drm_int2fixp(pixel->r)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[9]), drm_int2fixp(pixel->g)) +
+	     drm_fixp_mul(drm_sm2fixp(matrix->matrix[10]), drm_int2fixp(pixel->b)) +
+	     drm_sm2fixp(matrix->matrix[11]);
+
+	pixel->r = drm_fixp2int(rf);
+	pixel->g = drm_fixp2int(gf);
+	pixel->b = drm_fixp2int(bf);
+}
+
 static void apply_colorop(struct pixel_argb_s32 *pixel, struct drm_colorop *colorop)
 {
 	/* TODO is this right? */
@@ -185,6 +209,9 @@ static void apply_colorop(struct pixel_argb_s32 *pixel, struct drm_colorop *colo
 				DRM_DEBUG_DRIVER("unkown colorop 1D curve type %d\n", colorop_state->curve_1d_type);
 				break;
 		}
+	} else if (colorop->type == DRM_COLOROP_CTM_3X4) {
+		if (colorop_state->data)
+			apply_3x4_matrix(pixel, (struct drm_color_ctm_3x4 *) colorop_state->data->data);
 	}
 
 }
-- 
2.42.1