Re: [PATCH 22/25] media: sti/bdisp: fix pm_runtime_get_sync() usage count

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Wed, 5 May 2021 11:42:12 +0200
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

> The pm_runtime_get_sync() internally increments the
> dev->power.usage_count without decrementing it, even on errors.
> 
> The bdisp_start_streaming() doesn't take it into account, which
> would unbalance PM usage counter at bdisp_stop_streaming().
> 
> The logic at bdisp_probe() is correct, but the best is to use
> the same call along the driver.
> 
> So, replace it by the new pm_runtime_resume_and_get(), introduced by:
> commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> in order to properly decrement the usage counter, avoiding
> a potential PM usage counter leak.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/media/platform/sti/bdisp/bdisp-v4l2.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/sti/bdisp/bdisp-v4l2.c b/drivers/media/platform/sti/bdisp/bdisp-v4l2.c
> index 060ca85f64d5..85288da9d2ae 100644
> --- a/drivers/media/platform/sti/bdisp/bdisp-v4l2.c
> +++ b/drivers/media/platform/sti/bdisp/bdisp-v4l2.c
> @@ -499,7 +499,7 @@ static int bdisp_start_streaming(struct vb2_queue *q, unsigned int count)
>  {
>  	struct bdisp_ctx *ctx = q->drv_priv;
>  	struct vb2_v4l2_buffer *buf;
> -	int ret = pm_runtime_get_sync(ctx->bdisp_dev->dev);
> +	int ret = pm_runtime_resume_and_get(ctx->bdisp_dev->dev);
>  
>  	if (ret < 0) {
>  		dev_err(ctx->bdisp_dev->dev, "failed to set runtime PM\n");
> @@ -1364,10 +1364,10 @@ static int bdisp_probe(struct platform_device *pdev)
>  
>  	/* Power management */
>  	pm_runtime_enable(dev);
> -	ret = pm_runtime_get_sync(dev);
> +	ret = pm_runtime_resume_and_get(dev);
>  	if (ret < 0) {
>  		dev_err(dev, "failed to set PM\n");
> -		goto err_pm;
> +		goto err_remove;
>  	}
>  
>  	/* Filters */
> @@ -1395,6 +1395,7 @@ static int bdisp_probe(struct platform_device *pdev)
>  	bdisp_hw_free_filters(bdisp->dev);
>  err_pm:
>  	pm_runtime_put(dev);
> +err_remove:
>  	bdisp_debugfs_remove(bdisp);
>  	v4l2_device_unregister(&bdisp->v4l2_dev);
>  err_clk: