2021-05-05 09:43:49

by Mauro Carvalho Chehab

Subject: [PATCH 14/25] media: renesas-ceu: Properly check for PM errors

Right now, the driver just assumes that PM runtime resume
worked, but it may fail.

Well, the pm_runtime_get_sync() internally increments the
dev->power.usage_count without decrementing it, even on errors.

So, using it is tricky. Let's 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")
and return an error if something bad happens.

This should ensure that the PM runtime usage_count will be
properly decremented if an error happens at open time.

Reviewed-by: Jonathan Cameron <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
---
drivers/media/platform/renesas-ceu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/renesas-ceu.c b/drivers/media/platform/renesas-ceu.c
index cd137101d41e..17f01b6e3fe0 100644
--- a/drivers/media/platform/renesas-ceu.c
+++ b/drivers/media/platform/renesas-ceu.c
@@ -1099,10 +1099,10 @@ static int ceu_open(struct file *file)

mutex_lock(&ceudev->mlock);
/* Causes soft-reset and sensor power on on first open */
- pm_runtime_get_sync(ceudev->dev);
+ ret = pm_runtime_resume_and_get(ceudev->dev);
mutex_unlock(&ceudev->mlock);

- return 0;
+ return ret;
}

static int ceu_release(struct file *file)
--
2.30.2

2021-05-05 09:57:43

by jacopo mondi

Subject: Re: [PATCH 14/25] media: renesas-ceu: Properly check for PM errors

Hi Mauro,

On Wed, May 05, 2021 at 11:42:04AM +0200, Mauro Carvalho Chehab wrote:
> Right now, the driver just assumes that PM runtime resume
> worked, but it may fail.
>
> Well, the pm_runtime_get_sync() internally increments the
> dev->power.usage_count without decrementing it, even on errors.
>
> So, using it is tricky. Let's 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")
> and return an error if something bad happens.
>
> This should ensure that the PM runtime usage_count will be
> properly decremented if an error happens at open time.
>
> Reviewed-by: Jonathan Cameron <[email protected]>
> Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Looks good!
Acked-by: Jacopo Mondi <[email protected]>

Thanks
j

> ---
> drivers/media/platform/renesas-ceu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/renesas-ceu.c b/drivers/media/platform/renesas-ceu.c
> index cd137101d41e..17f01b6e3fe0 100644
> --- a/drivers/media/platform/renesas-ceu.c
> +++ b/drivers/media/platform/renesas-ceu.c
> @@ -1099,10 +1099,10 @@ static int ceu_open(struct file *file)
>
> mutex_lock(&ceudev->mlock);
> /* Causes soft-reset and sensor power on on first open */
> - pm_runtime_get_sync(ceudev->dev);
> + ret = pm_runtime_resume_and_get(ceudev->dev);
> mutex_unlock(&ceudev->mlock);
>
> - return 0;
> + return ret;
> }
>
> static int ceu_release(struct file *file)
> --
> 2.30.2
>