drm/exynos: check a pixel format to a particular window layer

This patch checks if a requested window supports alpha channel or not.

In case of s3c64xx, window 0 doesn't support alpha channel so if
the request pixel format is ARGB8888 then change it to XRGB8888.
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_fimd.c

@@ -66,11 +66,13 @@ struct fimd_driver_data {
 
 	unsigned int has_shadowcon:1;
 	unsigned int has_clksel:1;
+	unsigned int has_limited_fmt:1;
 };
 
 static struct fimd_driver_data s3c64xx_fimd_driver_data = {
 	.timing_base = 0x0,
 	.has_clksel = 1,
+	.has_limited_fmt = 1,
 };
 
 static struct fimd_driver_data exynos4_fimd_driver_data = {
@@ -420,6 +422,15 @@ static void fimd_win_set_pixfmt(struct device *dev, unsigned int win)
 
 	val = WINCONx_ENWIN;
 
+	/*
+	 * In case of s3c64xx, window 0 doesn't support alpha channel.
+	 * So the request format is ARGB8888 then change it to XRGB8888.
+	 */
+	if (ctx->driver_data->has_limited_fmt && !win) {
+		if (win_data->pixel_format == DRM_FORMAT_ARGB8888)
+			win_data->pixel_format = DRM_FORMAT_XRGB8888;
+	}
+
 	switch (win_data->pixel_format) {
 	case DRM_FORMAT_C8:
 		val |= WINCON0_BPPMODE_8BPP_PALETTE;