drm: mali-dp: Add YUV->RGB conversion support for video layers

Internally Mali DP uses an RGB pipeline so video layers that support
YUV input buffers need to convert the input data to RGB. The YUV
buffers can have various encodings and this patch introduces support
for BT.601, BT.709 and BT.2020 encodings, both limited and full ranges.

This patch adds support for specifying the color encoding of the
input buffers for the planes that are backed by the video layers
and programs the YUV2RGB coefficients into hardware based on the
selected encoding.

Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
[updated to use standard properties]
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/arm/malidp_planes.c

@@ -266,6 +266,60 @@ static void malidp_de_set_plane_pitches(struct malidp_plane *mp,
 				mp->layer->stride_offset + i * 4);
 }
 
+static const s16
+malidp_yuv2rgb_coeffs[][DRM_COLOR_RANGE_MAX][MALIDP_COLORADJ_NUM_COEFFS] = {
+	[DRM_COLOR_YCBCR_BT601][DRM_COLOR_YCBCR_LIMITED_RANGE] = {
+		1192,    0, 1634,
+		1192, -401, -832,
+		1192, 2066,    0,
+		  64,  512,  512
+	},
+	[DRM_COLOR_YCBCR_BT601][DRM_COLOR_YCBCR_FULL_RANGE] = {
+		1024,    0, 1436,
+		1024, -352, -731,
+		1024, 1815,    0,
+		   0,  512,  512
+	},
+	[DRM_COLOR_YCBCR_BT709][DRM_COLOR_YCBCR_LIMITED_RANGE] = {
+		1192,    0, 1836,
+		1192, -218, -546,
+		1192, 2163,    0,
+		  64,  512,  512
+	},
+	[DRM_COLOR_YCBCR_BT709][DRM_COLOR_YCBCR_FULL_RANGE] = {
+		1024,    0, 1613,
+		1024, -192, -479,
+		1024, 1900,    0,
+		   0,  512,  512
+	},
+	[DRM_COLOR_YCBCR_BT2020][DRM_COLOR_YCBCR_LIMITED_RANGE] = {
+		1024,    0, 1476,
+		1024, -165, -572,
+		1024, 1884,    0,
+		   0,  512,  512
+	},
+	[DRM_COLOR_YCBCR_BT2020][DRM_COLOR_YCBCR_FULL_RANGE] = {
+		1024,    0, 1510,
+		1024, -168, -585,
+		1024, 1927,    0,
+		   0,  512,  512
+	}
+};
+
+static void malidp_de_set_color_encoding(struct malidp_plane *plane,
+					 enum drm_color_encoding enc,
+					 enum drm_color_range range)
+{
+	unsigned int i;
+
+	for (i = 0; i < MALIDP_COLORADJ_NUM_COEFFS; i++) {
+		/* coefficients are signed, two's complement values */
+		malidp_hw_write(plane->hwdev, malidp_yuv2rgb_coeffs[enc][range][i],
+				plane->layer->base + plane->layer->yuv2rgb_offset +
+				i * 4);
+	}
+}
+
 static void malidp_de_plane_update(struct drm_plane *plane,
 				   struct drm_plane_state *old_state)
 {
@@ -297,6 +351,11 @@ static void malidp_de_plane_update(struct drm_plane *plane,
 	malidp_de_set_plane_pitches(mp, ms->n_planes,
 				    plane->state->fb->pitches);
 
+	if ((plane->state->color_encoding != old_state->color_encoding) ||
+	    (plane->state->color_range != old_state->color_range))
+		malidp_de_set_color_encoding(mp, plane->state->color_encoding,
+					     plane->state->color_range);
+
 	malidp_hw_write(mp->hwdev, LAYER_H_VAL(src_w) | LAYER_V_VAL(src_h),
 			mp->layer->base + MALIDP_LAYER_SIZE);
 
@@ -438,6 +497,26 @@ int malidp_de_planes_init(struct drm_device *drm)
 		drm_plane_create_rotation_property(&plane->base, DRM_MODE_ROTATE_0, flags);
 		malidp_hw_write(malidp->dev, MALIDP_ALPHA_LUT,
 				plane->layer->base + MALIDP_LAYER_COMPOSE);
+
+		/* Attach the YUV->RGB property only to video layers */
+		if (id & (DE_VIDEO1 | DE_VIDEO2)) {
+			/* default encoding for YUV->RGB is BT601 NARROW */
+			enum drm_color_encoding enc = DRM_COLOR_YCBCR_BT601;
+			enum drm_color_range range = DRM_COLOR_YCBCR_LIMITED_RANGE;
+
+			ret = drm_plane_create_color_properties(&plane->base,
+					BIT(DRM_COLOR_YCBCR_BT601) | \
+					BIT(DRM_COLOR_YCBCR_BT709) | \
+					BIT(DRM_COLOR_YCBCR_BT2020),
+					BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) | \
+					BIT(DRM_COLOR_YCBCR_FULL_RANGE),
+					enc, range);
+			if (!ret)
+				/* program the HW registers */
+				malidp_de_set_color_encoding(plane, enc, range);
+			else
+				DRM_WARN("Failed to create video layer %d color properties\n", id);
+		}
 	}
 
 	kfree(formats);