drm/sun4i: backend: Support YUV planes

Now that we have the guarantee that we will have only a single YUV plane,
actually support them. The way it works is not really straightforward,
since we first need to enable the YUV mode in the plane that we want to
setup, and then we have a few registers to setup the YUV buffer and
parameters.

We also need to setup the color correction to actually have something
displayed.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/66088c1398bd3189123f28a89a7ccc669fe9f296.1519931807.git-series.maxime.ripard@bootlin.com

drivers/gpu/drm/sun4i/sun4i_backend.c

@@ -42,6 +42,24 @@ static const u32 sunxi_rgb2yuv_coef[12] = {
 	0x000001c1, 0x00003e88, 0x00003fb8, 0x00000808
 };
 
+/*
+ * These coefficients are taken from the A33 BSP from Allwinner.
+ *
+ * The formula is for each component, each coefficient being multiplied by
+ * 1024 and each constant being multiplied by 16:
+ * G = 1.164 * Y - 0.391 * U - 0.813 * V + 135
+ * R = 1.164 * Y + 1.596 * V - 222
+ * B = 1.164 * Y + 2.018 * U + 276
+ *
+ * This seems to be a conversion from Y[16:235] UV[16:240] to RGB[0:255],
+ * following the BT601 spec.
+ */
+static const u32 sunxi_bt601_yuv2rgb_coef[12] = {
+	0x000004a7, 0x00001e6f, 0x00001cbf, 0x00000877,
+	0x000004a7, 0x00000000, 0x00000662, 0x00003211,
+	0x000004a7, 0x00000812, 0x00000000, 0x00002eb1,
+};
+
 static inline bool sun4i_backend_format_is_planar_yuv(uint32_t format)
 {
 	switch (format) {
@@ -198,6 +216,61 @@ int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
 	return 0;
 }
 
+static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
+					   int layer, struct drm_plane *plane)
+{
+	struct drm_plane_state *state = plane->state;
+	struct drm_framebuffer *fb = state->fb;
+	uint32_t format = fb->format->format;
+	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
+		regmap_write(backend->engine.regs,
+			     SUN4I_BACKEND_YGCOEF_REG(i),
+			     sunxi_bt601_yuv2rgb_coef[i]);
+
+	/*
+	 * We should do that only for a single plane, but the
+	 * framebuffer's atomic_check has our back on this.
+	 */
+	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
+			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
+			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
+
+	/* TODO: Add support for the multi-planar YUV formats */
+	if (sun4i_backend_format_is_packed_yuv422(format))
+		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
+	else
+		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", format);
+
+	/*
+	 * Allwinner seems to list the pixel sequence from right to left, while
+	 * DRM lists it from left to right.
+	 */
+	switch (format) {
+	case DRM_FORMAT_YUYV:
+		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
+		break;
+	case DRM_FORMAT_YVYU:
+		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
+		break;
+	case DRM_FORMAT_UYVY:
+		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
+		break;
+	case DRM_FORMAT_VYUY:
+		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
+		break;
+	default:
+		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
+				 format);
+	}
+
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
+
+	return 0;
+}
+
 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 				       int layer, struct drm_plane *plane)
 {
@@ -207,6 +280,10 @@ int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 	u32 val;
 	int ret;
 
+	/* Clear the YUV mode */
+	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
+			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
+
 	if (plane->state->crtc)
 		interlaced = plane->state->crtc->state->adjusted_mode.flags
 			& DRM_MODE_FLAG_INTERLACE;
@@ -218,6 +295,9 @@ int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
 			 interlaced ? "on" : "off");
 
+	if (sun4i_backend_format_is_yuv(fb->format->format))
+		return sun4i_backend_update_yuv_format(backend, layer, plane);
+
 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &val);
 	if (ret) {
 		DRM_DEBUG_DRIVER("Invalid format\n");
@@ -255,6 +335,21 @@ int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
 	return 0;
 }
 
+static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
+					   struct drm_framebuffer *fb,
+					   dma_addr_t paddr)
+{
+	/* TODO: Add support for the multi-planar YUV formats */
+	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
+
+	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
+		     fb->pitches[0] * 8);
+
+	return 0;
+}
+
 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
 				      int layer, struct drm_plane *plane)
 {
@@ -280,6 +375,9 @@ int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
 	 */
 	paddr -= PHYS_OFFSET;
 
+	if (sun4i_backend_format_is_yuv(fb->format->format))
+		return sun4i_backend_update_yuv_buffer(backend, fb, paddr);
+
 	/* Write the 32 lower bits of the address (in bits) */
 	lo_paddr = paddr << 3;
 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);

drivers/gpu/drm/sun4i/sun4i_backend.h

@@ -72,6 +72,7 @@
 #define SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(x)		((x) << 15)
 #define SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK	GENMASK(11, 10)
 #define SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(x)			((x) << 10)
+#define SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN		BIT(2)
 #define SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN		BIT(1)
 
 #define SUN4I_BACKEND_ATTCTL_REG1(l)		(0x8a0 + (0x4 * (l)))
@@ -110,7 +111,23 @@
 #define SUN4I_BACKEND_SPREN_REG			0x900
 #define SUN4I_BACKEND_SPRFMTCTL_REG		0x908
 #define SUN4I_BACKEND_SPRALPHACTL_REG		0x90c
+
 #define SUN4I_BACKEND_IYUVCTL_REG		0x920
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_MASK		GENMASK(14, 12)
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV444		(4 << 12)
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422		(3 << 12)
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_PLANAR_YUV444		(2 << 12)
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_PLANAR_YUV222		(1 << 12)
+#define SUN4I_BACKEND_IYUVCTL_FBFMT_PLANAR_YUV111		(0 << 12)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_MASK			GENMASK(9, 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_YVYU				(3 << 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_VYUY				(2 << 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_YUYV				(1 << 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_UYVY				(0 << 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_VUYA				(1 << 8)
+#define SUN4I_BACKEND_IYUVCTL_FBPS_AYUV				(0 << 8)
+#define SUN4I_BACKEND_IYUVCTL_EN			BIT(0)
+
 #define SUN4I_BACKEND_IYUVADD_REG(c)		(0x930 + (0x4 * (c)))
 
 #define SUN4I_BACKEND_IYUVLINEWIDTH_REG(c)	(0x940 + (0x4 * (c)))

drivers/gpu/drm/sun4i/sun4i_layer.c

@@ -134,7 +134,11 @@ static const uint32_t sun4i_backend_layer_formats[] = {
 	DRM_FORMAT_RGBA4444,
 	DRM_FORMAT_RGB888,
 	DRM_FORMAT_RGB565,
+	DRM_FORMAT_UYVY,
+	DRM_FORMAT_VYUY,
 	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_YUYV,
+	DRM_FORMAT_YVYU,
 };
 
 static struct sun4i_layer *sun4i_layer_init_one(struct drm_device *drm,