drm/mediatek: Add dma dev get function

This is a preparation for adding support for the ovl_adaptor sub driver
Ovl_adaptor is a DRM sub driver, which doesn't have dma dev. Add
dma_dev_get function for getting representative dma dev in ovl_adaptor.
Signed-off-by: Nancy.Lin <nancy.lin@mediatek.com>
Reviewed-by: AngeloGioachino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20230321121859.2355-5-nancy.lin@mediatek.com/Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -58,6 +58,7 @@ struct mtk_drm_crtc {
 #endif
 
 	struct device			*mmsys_dev;
+	struct device			*dma_dev;
 	struct mtk_mutex		*mutex;
 	unsigned int			ddp_comp_nr;
 	struct mtk_ddp_comp		**ddp_comp;
@@ -867,6 +868,13 @@ static int mtk_drm_crtc_init_comp_planes(struct drm_device *drm_dev,
 	return 0;
 }
 
+struct device *mtk_drm_crtc_dma_dev_get(struct drm_crtc *crtc)
+{
+	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
+
+	return mtk_crtc->dma_dev;
+}
+
 int mtk_drm_crtc_create(struct drm_device *drm_dev,
 			const enum mtk_ddp_comp_id *path, unsigned int path_len)
 {
@@ -957,6 +965,13 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 			return ret;
 	}
 
+	/*
+	 * Default to use the first component as the dma dev.
+	 * In the case of ovl_adaptor sub driver, it needs to use the
+	 * dma_dev_get function to get representative dma dev.
+	 */
+	mtk_crtc->dma_dev = mtk_ddp_comp_dma_dev_get(&priv->ddp_comp[path[0]]);
+
 	ret = mtk_drm_crtc_init(drm_dev, mtk_crtc, pipe);
 	if (ret < 0)
 		return ret;

drivers/gpu/drm/mediatek/mtk_drm_crtc.h

@@ -22,5 +22,6 @@ int mtk_drm_crtc_plane_check(struct drm_crtc *crtc, struct drm_plane *plane,
 			     struct mtk_plane_state *state);
 void mtk_drm_crtc_async_update(struct drm_crtc *crtc, struct drm_plane *plane,
 			       struct drm_atomic_state *plane_state);
+struct device *mtk_drm_crtc_dma_dev_get(struct drm_crtc *crtc);
 
 #endif /* MTK_DRM_CRTC_H */

drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h

@@ -71,6 +71,7 @@ struct mtk_ddp_comp_funcs {
 	void (*bgclr_in_off)(struct device *dev);
 	void (*ctm_set)(struct device *dev,
 			struct drm_crtc_state *state);
+	struct device * (*dma_dev_get)(struct device *dev);
 	const u32 *(*get_formats)(struct device *dev);
 	size_t (*get_num_formats)(struct device *dev);
 };
@@ -205,6 +206,13 @@ static inline void mtk_ddp_ctm_set(struct mtk_ddp_comp *comp,
 		comp->funcs->ctm_set(comp->dev, state);
 }
 
+static inline struct device *mtk_ddp_comp_dma_dev_get(struct mtk_ddp_comp *comp)
+{
+	if (comp->funcs && comp->funcs->dma_dev_get)
+		return comp->funcs->dma_dev_get(comp->dev);
+	return comp->dev;
+}
+
 static inline
 const u32 *mtk_ddp_comp_get_formats(struct mtk_ddp_comp *comp)
 {