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SubjectRe: [PATCH 58/78] media: exynos-gsc: use pm_runtime_resume_and_get()
Em Tue, 27 Apr 2021 11:30:55 +0200
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> escreveu:

> Em Tue, 27 Apr 2021 10:18:12 +0200
> Sylwester Nawrocki <s.nawrocki@samsung.com> 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@kernel.org>
> > > ---
> > > drivers/media/platform/exynos-gsc/gsc-core.c | 3 +--
> > > drivers/media/platform/exynos-gsc/gsc-m2m.c | 2 +-
> > > 2 files changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/media/platform/exynos-gsc/gsc-core.c b/drivers/media/platform/exynos-gsc/gsc-core.c
> > > index 9f41c2e7097a..9d5841194f6b 100644
> > > --- a/drivers/media/platform/exynos-gsc/gsc-core.c
> > > +++ b/drivers/media/platform/exynos-gsc/gsc-core.c
> > > @@ -1210,7 +1210,7 @@ static int gsc_remove(struct platform_device *pdev)
> > > struct gsc_dev *gsc = platform_get_drvdata(pdev);
> > > int i;
> > >
> > > - pm_runtime_get_sync(&pdev->dev);
> > > + pm_runtime_resume_and_get(&pdev->dev);
> > >
> > > gsc_unregister_m2m_device(gsc);
> > > v4l2_device_unregister(&gsc->v4l2_dev);
> > > @@ -1219,7 +1219,6 @@ static int gsc_remove(struct platform_device *pdev)
> > > for (i = 0; i < gsc->num_clocks; i++)
> > > clk_disable_unprepare(gsc->clock[i]);
> > >
> > > - pm_runtime_put_noidle(&pdev->dev);
> >
> > If we do this then the device usage count will not get decremented
> > after the pm_runtime_resume_and_get() call above and after driver
> > unload/load cycle it will not be possible to suspend the device.
> > I wouldn't be changing anything in gsc_remove(), pm_runtime_get_sync()
> > works better in that case.
>
> Good point.
>
> Actually, I don't see any reason why to call a PM resume
> function - either being pm_runtime_get_sync() or
> pm_runtime_resume_and_get().
>
> The code there could simply be:
>
> static int gsc_remove(struct platform_device *pdev)
> {
> struct gsc_dev *gsc = platform_get_drvdata(pdev);
> int i;
>
> gsc_unregister_m2m_device(gsc);
> v4l2_device_unregister(&gsc->v4l2_dev);
>
> vb2_dma_contig_clear_max_seg_size(&pdev->dev);
> for (i = 0; i < gsc->num_clocks; i++)
> clk_disable_unprepare(gsc->clock[i]);
>
> pm_runtime_disable(&pdev->dev);
>
> dev_dbg(&pdev->dev, "%s driver unloaded\n", pdev->name);
> return 0;
> }
>
> Eventually also adding:
> pm_runtime_suspended(&pdev->dev);

In time: I actually meant:

pm_runtime_set_suspended(&pdev->dev);

but after double-checking the PM runtime code, it sounds to me that
just calling pm_runtime_disable() would be enough. Not 100% sure
here. Btw, some media drivers call it after pm_runtime_disable(),
while others don't do.

Thanks,
Mauro

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