drm/mediatek: add third ddp path

This patch create third crtc by third ddp path
Signed-off-by: Stu Hsieh <stu.hsieh@mediatek.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -539,6 +539,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 	int ret;
 	int i;
 
+	if (!path)
+		return 0;
+
 	for (i = 0; i < path_len; i++) {
 		enum mtk_ddp_comp_id comp_id = path[i];
 		struct device_node *node;

drivers/gpu/drm/mediatek/mtk_drm_drv.c

@@ -232,6 +232,11 @@ static int mtk_drm_kms_init(struct drm_device *drm)
 	if (ret < 0)
 		goto err_component_unbind;
 
+	ret = mtk_drm_crtc_create(drm, private->data->third_path,
+				  private->data->third_len);
+	if (ret < 0)
+		goto err_component_unbind;
+
 	/* Use OVL device for all DMA memory allocations */
 	np = private->comp_node[private->data->main_path[0]] ?:
 	     private->comp_node[private->data->ext_path[0]];

drivers/gpu/drm/mediatek/mtk_drm_drv.h

@@ -17,7 +17,7 @@
 #include <linux/io.h>
 #include "mtk_drm_ddp_comp.h"
 
-#define MAX_CRTC	2
+#define MAX_CRTC	3
 #define MAX_CONNECTOR	2
 
 struct device;
@@ -33,6 +33,9 @@ struct mtk_mmsys_driver_data {
 	unsigned int main_len;
 	const enum mtk_ddp_comp_id *ext_path;
 	unsigned int ext_len;
+	const enum mtk_ddp_comp_id *third_path;
+	unsigned int third_len;
+
 	bool shadow_register;
 };