[PATCH] drm/mediatek: fix crtc index computation

[Fabien Parent <fparent@xxxxxxxxxxxx>]

The code always assume that the main path is enabled, which is not
always the case. When the main path is not enabled, the CRTC index
of the ext path is incorrect which makes the secondary path
not usable. Fix the CRTC index calculation.

Signed-off-by: Fabien Parent <fparent@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 46 +++++++++++++++------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
index 5d7504a72b11..6f2abfc608fb 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
@@ -430,25 +430,47 @@ int mtk_ddp_comp_get_id(struct device_node *node,
 	return -EINVAL;
 }
 
+static bool mtk_drm_comp_is_enabled(struct drm_device *drm,
+				    const enum mtk_ddp_comp_id *path,
+				    unsigned int path_len)
+{
+	struct mtk_drm_private *priv = drm->dev_private;
+
+	return path && path_len && !!priv->comp_node[path[path_len - 1]];
+}
+
 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;
+	unsigned int index = 0;
 
-	if (mtk_drm_find_comp_in_ddp(dev, private->data->main_path, private->data->main_len,
+	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");
+		return BIT(index);
+
+	if (mtk_drm_comp_is_enabled(drm, private->data->main_path,
+				    private->data->main_len))
+		index++;
 
-	return ret;
+	if (mtk_drm_find_comp_in_ddp(dev, private->data->ext_path,
+				     private->data->ext_len,
+				     private->ddp_comp))
+		return BIT(index);
+
+	if (mtk_drm_comp_is_enabled(drm, private->data->ext_path,
+				    private->data->ext_len))
+		index++;
+
+	if (mtk_drm_find_comp_in_ddp(dev, private->data->third_path,
+					  private->data->third_len,
+					  private->ddp_comp))
+		return BIT(index);
+
+	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,
-- 
2.36.1