drm/mediatek: Add encoder_index interface for mtk_ddp_comp_funcs

To support dynamic connector selection function, each ddp_comp need to
get their encoder_index to identify which connector should be selected.

Add encoder_index interface for mtk_ddp_comp_funcs to get the encoder
identifier by drm_encoder_index().
Then drm driver will call mtk_ddp_comp_encoder_index_set() to store the
encoder_index to each ddp_comp in connector routes.
Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231004024013.18956-5-jason-jh.lin@mediatek.com/Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h

@@ -80,12 +80,14 @@ struct mtk_ddp_comp_funcs {
 	void (*disconnect)(struct device *dev, struct device *mmsys_dev, unsigned int next);
 	void (*add)(struct device *dev, struct mtk_mutex *mutex);
 	void (*remove)(struct device *dev, struct mtk_mutex *mutex);
+	unsigned int (*encoder_index)(struct device *dev);
 };
 
 struct mtk_ddp_comp {
 	struct device *dev;
 	int irq;
 	unsigned int id;
+	int encoder_index;
 	const struct mtk_ddp_comp_funcs *funcs;
 };
 
@@ -275,6 +277,12 @@ static inline bool mtk_ddp_comp_disconnect(struct mtk_ddp_comp *comp, struct dev
 	return false;
 }
 
+static inline void mtk_ddp_comp_encoder_index_set(struct mtk_ddp_comp *comp)
+{
+	if (comp->funcs && comp->funcs->encoder_index)
+		comp->encoder_index = (int)comp->funcs->encoder_index(comp->dev);
+}
+
 int mtk_ddp_comp_get_id(struct device_node *node,
 			enum mtk_ddp_comp_type comp_type);
 unsigned int mtk_drm_find_possible_crtc_by_comp(struct drm_device *drm,