Re: [PATCH] media: vsp1: Fix runtime PM imbalance in vsp1_probe

Laurent Pinchart
2020-06-08T01:55:19Z

Hi Dinghao,

Thank you for the patch.

On Sat, May 23, 2020 at 07:54:26PM +0800, Dinghao Liu wrote:
> pm_runtime_get_sync() increments the runtime PM usage counter even
> when it returns an error code. Thus a pairing decrement is needed on
> the error handling path to keep the counter balanced.

I wonder how many bugs we have today, and how many bugs will keep
appearing in the future, due to this historical design mistake :-(

> Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
> ---
> drivers/media/platform/vsp1/vsp1_drv.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/vsp1/vsp1_drv.c b/drivers/media/platform/vsp1/vsp1_drv.c
> index c650e45bb0ad..017a54f2fdd8 100644
> --- a/drivers/media/platform/vsp1/vsp1_drv.c
> +++ b/drivers/media/platform/vsp1/vsp1_drv.c
> @@ -846,8 +846,10 @@ static int vsp1_probe(struct platform_device *pdev)
> pm_runtime_enable(&pdev->dev);
>
> ret = pm_runtime_get_sync(&pdev->dev);
> - if (ret < 0)
> + if (ret < 0) {
> + pm_runtime_put_sync(&pdev->dev);
> goto done;
> + }

This change looks good to me, but we also need a similar change in the
vsp1_device_get() function if I'm not mistaken. Could you combine both
in the same patch ?

>
> vsp1->version = vsp1_read(vsp1, VI6_IP_VERSION);
> pm_runtime_put_sync(&pdev->dev);