[PATCH] media: platform: mtk-mdp3: Fix SCP device refcounting

[PATCH] media: platform: mtk-mdp3: Fix SCP device refcounting

[Guangshuo Li]

mdp_probe() first tries to get the SCP handle with scp_get(). When that
fails, it falls back to looking up the SCP platform device with
__get_pdev_by_id() and then reads its driver data.

The fallback lookup returns the platform device with a reference, just
like scp_get() does. However, the fallback path currently drops that
reference immediately after platform_get_drvdata(). The driver later
still calls scp_put(mdp->scp) unconditionally from the probe error path
and from mdp_video_device_release(), which drops the SCP device
reference again.

Keep the fallback reference until the existing scp_put() call, so that
the fallback path follows the same ownership rules as the scp_get()
path.

Fixes: 8f6f3aa21517 ("media: platform: mtk-mdp3: fix device leaks at probe")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
index 8f4da4cf55d2..121b1006ffdc 100644
--- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
+++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
@@ -294,7 +294,6 @@ static int mdp_probe(struct platform_device *pdev)
 			goto err_destroy_clock_wq;
 		}
 		mdp->scp = platform_get_drvdata(mm_pdev);
-		put_device(&mm_pdev->dev);
 	}
 
 	mdp->rproc_handle = scp_get_rproc(mdp->scp);
-- 
2.43.0

Re: [PATCH] media: platform: mtk-mdp3: Fix SCP device refcounting

[Johan Hovold]

On Sun, Jul 05, 2026 at 01:31:19AM +0800, Guangshuo Li wrote:
> mdp_probe() first tries to get the SCP handle with scp_get(). When that
> fails, it falls back to looking up the SCP platform device with
> __get_pdev_by_id() and then reads its driver data.
> 
> The fallback lookup returns the platform device with a reference, just
> like scp_get() does. However, the fallback path currently drops that
> reference immediately after platform_get_drvdata(). The driver later
> still calls scp_put(mdp->scp) unconditionally from the probe error path
> and from mdp_video_device_release(), which drops the SCP device
> reference again.
> 
> Keep the fallback reference until the existing scp_put() call, so that
> the fallback path follows the same ownership rules as the scp_get()
> path.

Thanks for catching that.
 
> Fixes: 8f6f3aa21517 ("media: platform: mtk-mdp3: fix device leaks at probe")

This one should also go to stable:

Cc: stable@vger.kernel.org

> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>

Reviewed-by: Johan Hovold <johan@kernel.org>

Johan