drm/sun4i: backend: Add a helper and a list for supported formats

In order to check whether the backend supports a specific format, an
explicit list and a related helper are introduced.

The prototype of this helper is added to the header so that it can be
called from sun4i_layer later (when introducing tiled mode support).
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181123092515.2511-5-paul.kocialkowski@bootlin.com

drivers/gpu/drm/sun4i/sun4i_backend.c

@@ -155,6 +155,33 @@ static int sun4i_backend_drm_format_to_layer(u32 format, u32 *mode)
 	return 0;
 }
 
+static const uint32_t sun4i_backend_formats[] = {
+	DRM_FORMAT_ARGB1555,
+	DRM_FORMAT_ARGB4444,
+	DRM_FORMAT_ARGB8888,
+	DRM_FORMAT_BGRX8888,
+	DRM_FORMAT_RGB565,
+	DRM_FORMAT_RGB888,
+	DRM_FORMAT_RGBA4444,
+	DRM_FORMAT_RGBA5551,
+	DRM_FORMAT_UYVY,
+	DRM_FORMAT_VYUY,
+	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_YUYV,
+	DRM_FORMAT_YVYU,
+};
+
+bool sun4i_backend_format_is_supported(uint32_t fmt)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(sun4i_backend_formats); i++)
+		if (sun4i_backend_formats[i] == fmt)
+			return true;
+
+	return false;
+}
+
 int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
 				     int layer, struct drm_plane *plane)
 {

drivers/gpu/drm/sun4i/sun4i_backend.h

@@ -198,6 +198,7 @@ engine_to_sun4i_backend(struct sunxi_engine *engine)
 
 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
 				int layer, bool enable);
+bool sun4i_backend_format_is_supported(uint32_t fmt);
 int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
 				     int layer, struct drm_plane *plane);
 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,