Re: [PATCH 57/78] media: exynos4-is: use pm_runtime_resume_and_get()

[Sylwester Nawrocki]

On 26.04.2021 15:12, Mauro Carvalho Chehab wrote:
> Em Sun, 25 Apr 2021 22:57:25 +0200
> Sylwester Nawrocki <snawrocki@xxxxxxxxxx> escreveu:
>
> > On 24.04.2021 08:45, Mauro Carvalho Chehab wrote:
> > > Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> > > added pm_runtime_resume_and_get() in order to automatically handle
> > > dev->power.usage_count decrement on errors.
> > >
> > > Use the new API, in order to cleanup the error check logic.
> > >
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>

> > > diff --git a/drivers/media/platform/exynos4-is/fimc-is.c b/drivers/media/platform/exynos4-is/fimc-is.c
> > > index 972d9601d236..bca35866cc74 100644
> > > --- a/drivers/media/platform/exynos4-is/fimc-is.c
> > > +++ b/drivers/media/platform/exynos4-is/fimc-is.c
> > > @@ -828,7 +828,7 @@ static int fimc_is_probe(struct platform_device *pdev)
> > >    			goto err_irq;
> > >    	}
> > >    
> > > -	ret = pm_runtime_get_sync(dev);
> > > +	ret = pm_runtime_resume_and_get(dev);
> > >    	if (ret < 0)
> > >    		goto err_pm;
> >
> > It seems you intended to use err_suspend label here. We don't need
> > a new label though, instead of err_pm we can jump to err_irq when
> > pm_runtime_resume_and_get() fails.
>
> Thanks! Will fix at the next version.
>
> > Note that when runtime PM is
> > disabled pm_runtime_resume_and_get() always returns 0.
>
> Ok, but there are a couple of conditions at rpm_resume() function
> at drivers/base/power/runtime.c (which is the code that actually
> handles those PM macros) that could make it to return errors,
> which are independent on the PM callbacks, like those:
>
>          if (dev->power.runtime_error)
>                  retval = -EINVAL;
>          else if (dev->power.disable_depth > 0)
>                  retval = -EACCES;
>
> and more might be added as the PM core changes.

Right, I looked only at !CONFIG_PM case, this is what the "if (!pm_runtime_enabled(dev))"
test and explicit fimc_is_runtime_{resume,suspend} calls were originally for.
Agreed, better not to rely too much on internal implementation as there is
no specific guarantees about return value at the API documentation.

Regards,
Sylwester

> > > @@ -862,6 +862,7 @@ static int fimc_is_probe(struct platform_device *pdev)
> > >    	fimc_is_unregister_subdevs(is);
> > >    err_pm:
> > >    	pm_runtime_put_noidle(dev);
> > > +err_suspend:
> > >    	if (!pm_runtime_enabled(dev))
> > >    		fimc_is_runtime_suspend(dev);
> > >    err_irq: