[PATCH] drm/mediatek: check for comp->funcs

[Hsin-Yi Wang]

There might be some comp that doesn't have funcs, eg. hdmi-connector.
Check for comp->funcs otherwise there will be NULL pointer dereference
crash.

Fixes: bd3de8cd782b ("drm/mediatek: Add gamma property according to hardware capability")
Fixes: 7395eab077f9 ("drm/mediatek: Add ctm property support")
Signed-off-by: Hsin-Yi Wang <hsinyi at chromium.org>
---
This patch is based on mediatek's drm branch:
https://github.com/ckhu-mediatek/linux.git-tags/commits/mediatek-drm-next-5.6

After
https://patchwork.freedesktop.org/patch/344477/?series=63328&rev=59,
there will also be funcs for hdmi-connector.
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index fb142fcfc353..7b392d6c71cc 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -808,11 +808,13 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 
 		mtk_crtc->ddp_comp[i] = comp;
 
-		if (comp->funcs->ctm_set)
-			has_ctm = true;
+		if (comp->funcs) {
+			if (comp->funcs->ctm_set)
+				has_ctm = true;
 
-		if (comp->funcs->gamma_set)
-			gamma_lut_size = MTK_LUT_SIZE;
+			if (comp->funcs->gamma_set)
+				gamma_lut_size = MTK_LUT_SIZE;
+		}
 	}
 
 	for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
-- 
2.25.0.rc1.283.g88dfdc4193-goog