drm/sun4i: frontend: Determine input format based on colorspace

Since all the RGB input formats have the same value for the DATA_FMT
field of the INPUT_FMT register, we can group them when the format is
known to be RGB. Here, we assume that a non-YUV format is RGB, because
the hardware does not support any other colorspace than RGB and YUV.

Use the DRM format info structure to check whether the format uses a
YUV colorspace.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190118145133.21281-6-paul.kocialkowski@bootlin.com

drivers/gpu/drm/sun4i/sun4i_frontend.c

@@ -108,14 +108,12 @@ static int
 sun4i_frontend_drm_format_to_input_fmt(const struct drm_format_info *format,
 				       u32 *val)
 {
-	switch (format->format) {
-	case DRM_FORMAT_XRGB8888:
+	if (!format->is_yuv)
 		*val = SUN4I_FRONTEND_INPUT_FMT_DATA_FMT_RGB;
-		return 0;
-
-	default:
+	else
 		return -EINVAL;
-	}
+
+	return 0;
 }
 
 static int