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SubjectRe: [PATCH 58/78] media: exynos-gsc: use pm_runtime_resume_and_get()
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On 27.04.2021 11:42, Mauro Carvalho Chehab wrote:
> 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.

I think if the device is brought into suspended state (e.g. by
disabling clocks as above) the pm_runtime_set_suspended() call
should be there. IOW a following sequence:

pm_runtime_disable(dev);
if (!pm_runtime_status_suspended(dev))
/* put device into suspended state (disable clocks,
voltage regulators, assert GPIOs, etc. */
pm_runtime_set_suspended(dev);

--
Regards,
Sylwester

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