mtk_drm_find_possible_crtc_by_comp() assumed that the main path will
always have the CRTC with id 0, the ext id 1 and the third id 2. This
is only true if the paths are all available. But paths are optional (see
also comment in mtk_drm_kms_init()), e.g. the main path might not be
enabled or available at all. Then the CRTC IDs will shift one up, e.g.
ext will be 1 and the third path will be 2.

To fix that, dynamically calculate the IDs by the precence of the paths.

Fixes: 5aa8e7647676 ("drm/mediatek: dpi/dsi: Change the getting possible_crtc 
way")
Suggested-by: Nícolas F. R. A. Prado <nfrapr...@collabora.com>
Signed-off-by: Michael Walle <mwa...@kernel.org>
---
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 41 ++++++++++++++-------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c 
b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
index 771f4e173353..f3064bff64e8 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
@@ -526,21 +526,34 @@ unsigned int mtk_drm_find_possible_crtc_by_comp(struct 
drm_device *drm,
                                                struct device *dev)
 {
        struct mtk_drm_private *private = drm->dev_private;
-       unsigned int ret = 0;
-
-       if (mtk_drm_find_comp_in_ddp(dev, private->data->main_path, 
private->data->main_len,
-                                    private->ddp_comp))
-               ret = BIT(0);
-       else if (mtk_drm_find_comp_in_ddp(dev, private->data->ext_path,
-                                         private->data->ext_len, 
private->ddp_comp))
-               ret = BIT(1);
-       else if (mtk_drm_find_comp_in_ddp(dev, private->data->third_path,
-                                         private->data->third_len, 
private->ddp_comp))
-               ret = BIT(2);
-       else
-               DRM_INFO("Failed to find comp in ddp table\n");
+       int i = 0;
+
+       if (private->data->main_path) {
+               if (mtk_drm_find_comp_in_ddp(dev, private->data->main_path,
+                                            private->data->main_len,
+                                            private->ddp_comp))
+                       return BIT(i);
+               i++;
+       }
+
+       if (private->data->ext_path) {
+               if (mtk_drm_find_comp_in_ddp(dev, private->data->ext_path,
+                                            private->data->ext_len,
+                                            private->ddp_comp))
+                       return BIT(i);
+               i++;
+       }
 
-       return ret;
+       if (private->data->third_path) {
+               if (mtk_drm_find_comp_in_ddp(dev, private->data->third_path,
+                                            private->data->third_len,
+                                            private->ddp_comp))
+                       return BIT(i);
+               i++;
+       }
+
+       DRM_INFO("Failed to find comp in ddp table\n");
+       return 0;
 }
 
 int mtk_ddp_comp_init(struct device_node *node, struct mtk_ddp_comp *comp,
-- 
2.39.2

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