Re: [PATCH v8 3/8] drm/mediatek: Fix using wrong drm private data to bind mediatek-drm

[Eugen Hristev]

On 8/2/23 17:47, Jason-JH.Lin wrote:

In mtk_drm_kms_init(), each element in all_drm_priv should has one
display path private data only, such as:
all_drm_priv[CRTC_MAIN] should has main_path data only
all_drm_priv[CRTC_EXT] should has ext_path data only
all_drm_priv[CRTC_THIRD] should has third_path data only

s/should has/should have/ ?

So we need to add the length checking for each display path before
assigning their drm private data into all_drm_priv array.

Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys 
support")
Signed-off-by: Jason-JH.Lin <jason-jh....@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@collabora.com>
Reviewed-by: CK Hu <ck...@mediatek.com>
---
  drivers/gpu/drm/mediatek/mtk_drm_drv.c | 16 +++++++++++++---
  1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c 
b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 89a38561ba27..c12886f31e54 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -351,6 +351,7 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)
  {
        struct mtk_drm_private *drm_priv = dev_get_drvdata(dev);
        struct mtk_drm_private *all_drm_priv[MAX_CRTC];
+       struct mtk_drm_private *temp_drm_priv;
        struct device_node *phandle = dev->parent->of_node;
        const struct of_device_id *of_id;
        struct device_node *node;
@@ -373,9 +374,18 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)
                if (!drm_dev || !dev_get_drvdata(drm_dev))
                        continue;

- all_drm_priv[cnt] = dev_get_drvdata(drm_dev);

-               if (all_drm_priv[cnt] && all_drm_priv[cnt]->mtk_drm_bound)
-                       cnt++;
+               temp_drm_priv = dev_get_drvdata(drm_dev);
+               if (temp_drm_priv) {

This is inside a 'for' loop right ?
Why don't you just 'continue' if temp_drm_priv is null ?

+                       if (temp_drm_priv->mtk_drm_bound)
+                               cnt++;
+
+                       if (temp_drm_priv->data->main_len)
+                               all_drm_priv[CRTC_MAIN] = temp_drm_priv;
+                       else if (temp_drm_priv->data->ext_len)
+                               all_drm_priv[CRTC_EXT] = temp_drm_priv;
+                       else if (temp_drm_priv->data->third_len)
+                               all_drm_priv[CRTC_THIRD] = temp_drm_priv;
+               }
        }

if (drm_priv->data->mmsys_dev_num == cnt) {