drm/mediatek: Add gamma property according to hardware capability

If there is no gamma function in the crtc
display path, don't add gamma property
for crtc

Fixes: 2f3f4dda ("drm/mediatek: Add gamma correction.")
Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -730,6 +730,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 	int pipe = priv->num_pipes;
 	int ret;
 	int i;
+	uint gamma_lut_size = 0;
 
 	if (!path)
 		return 0;
@@ -780,6 +781,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 		}
 
 		mtk_crtc->ddp_comp[i] = comp;
+
+		if (comp->funcs && comp->funcs->gamma_set)
+			gamma_lut_size = MTK_LUT_SIZE;
 	}
 
 	for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
@@ -800,8 +804,10 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 				NULL, pipe);
 	if (ret < 0)
 		return ret;
-	drm_mode_crtc_set_gamma_size(&mtk_crtc->base, MTK_LUT_SIZE);
-	drm_crtc_enable_color_mgmt(&mtk_crtc->base, 0, false, MTK_LUT_SIZE);
+
+	if (gamma_lut_size)
+		drm_mode_crtc_set_gamma_size(&mtk_crtc->base, gamma_lut_size);
+	drm_crtc_enable_color_mgmt(&mtk_crtc->base, 0, false, gamma_lut_size);
 	priv->num_pipes++;
 	mutex_init(&mtk_crtc->hw_lock);