drm/omap: fix missing scaler pixel fmt limitations

OMAP2 and OMAP3/AM4 have limitations with the scaler:
- OMAP2 can only scale XRGB8888
- OMAP3/AM4 can only scale XRGB8888, RGB565, YUYV and UYVY

The driver doesn't check these limitations, which leads to sync-lost
floods.

This patch adds a check for the pixel formats when scaling.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190930103840.18970-5-tomi.valkeinen@ti.com

drivers/gpu/drm/omapdrm/dss/dispc.c

@@ -114,6 +114,7 @@ struct dispc_features {
 	const unsigned int num_reg_fields;
 	const enum omap_overlay_caps *overlay_caps;
 	const u32 **supported_color_modes;
+	const u32 *supported_scaler_color_modes;
 	unsigned int num_mgrs;
 	unsigned int num_ovls;
 	unsigned int buffer_size_unit;
@@ -2499,6 +2500,19 @@ static int dispc_ovl_calc_scaling(struct dispc_device *dispc,
 	if (width == out_width && height == out_height)
 		return 0;
 
+	if (dispc->feat->supported_scaler_color_modes) {
+		const u32 *modes = dispc->feat->supported_scaler_color_modes;
+		unsigned int i;
+
+		for (i = 0; modes[i]; ++i) {
+			if (modes[i] == fourcc)
+				break;
+		}
+
+		if (modes[i] == 0)
+			return -EINVAL;
+	}
+
 	if (plane == OMAP_DSS_WB) {
 		switch (fourcc) {
 		case DRM_FORMAT_NV12:
@@ -4214,6 +4228,12 @@ static const u32 *omap4_dispc_supported_color_modes[] = {
 	DRM_FORMAT_RGBX8888),
 };
 
+static const u32 omap3_dispc_supported_scaler_color_modes[] = {
+	DRM_FORMAT_XRGB8888, DRM_FORMAT_RGB565, DRM_FORMAT_YUYV,
+	DRM_FORMAT_UYVY,
+	0,
+};
+
 static const struct dispc_features omap24xx_dispc_feats = {
 	.sw_start		=	5,
 	.fp_start		=	15,
@@ -4242,6 +4262,7 @@ static const struct dispc_features omap24xx_dispc_feats = {
 	.num_reg_fields		=	ARRAY_SIZE(omap2_dispc_reg_fields),
 	.overlay_caps		=	omap2_dispc_overlay_caps,
 	.supported_color_modes	=	omap2_dispc_supported_color_modes,
+	.supported_scaler_color_modes = COLOR_ARRAY(DRM_FORMAT_XRGB8888),
 	.num_mgrs		=	2,
 	.num_ovls		=	3,
 	.buffer_size_unit	=	1,
@@ -4276,6 +4297,7 @@ static const struct dispc_features omap34xx_rev1_0_dispc_feats = {
 	.num_reg_fields		=	ARRAY_SIZE(omap3_dispc_reg_fields),
 	.overlay_caps		=	omap3430_dispc_overlay_caps,
 	.supported_color_modes	=	omap3_dispc_supported_color_modes,
+	.supported_scaler_color_modes = omap3_dispc_supported_scaler_color_modes,
 	.num_mgrs		=	2,
 	.num_ovls		=	3,
 	.buffer_size_unit	=	1,
@@ -4310,6 +4332,7 @@ static const struct dispc_features omap34xx_rev3_0_dispc_feats = {
 	.num_reg_fields		=	ARRAY_SIZE(omap3_dispc_reg_fields),
 	.overlay_caps		=	omap3430_dispc_overlay_caps,
 	.supported_color_modes	=	omap3_dispc_supported_color_modes,
+	.supported_scaler_color_modes = omap3_dispc_supported_scaler_color_modes,
 	.num_mgrs		=	2,
 	.num_ovls		=	3,
 	.buffer_size_unit	=	1,
@@ -4344,6 +4367,7 @@ static const struct dispc_features omap36xx_dispc_feats = {
 	.num_reg_fields		=	ARRAY_SIZE(omap3_dispc_reg_fields),
 	.overlay_caps		=	omap3630_dispc_overlay_caps,
 	.supported_color_modes	=	omap3_dispc_supported_color_modes,
+	.supported_scaler_color_modes = omap3_dispc_supported_scaler_color_modes,
 	.num_mgrs		=	2,
 	.num_ovls		=	3,
 	.buffer_size_unit	=	1,
@@ -4378,6 +4402,7 @@ static const struct dispc_features am43xx_dispc_feats = {
 	.num_reg_fields		=	ARRAY_SIZE(omap3_dispc_reg_fields),
 	.overlay_caps		=	omap3430_dispc_overlay_caps,
 	.supported_color_modes	=	omap3_dispc_supported_color_modes,
+	.supported_scaler_color_modes = omap3_dispc_supported_scaler_color_modes,
 	.num_mgrs		=	1,
 	.num_ovls		=	3,
 	.buffer_size_unit	=	1,