linux-kernel - Re: [PATCH v3 06/79] media: exynos-gsc: don't resume at remove time

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Date:   Tue, 27 Apr 2021 13:21:32 +0200
From:   Sylwester Nawrocki <s.nawrocki@...sung.com>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v3 06/79] media: exynos-gsc: don't resume at remove time

On 27.04.2021 12:25, Mauro Carvalho Chehab wrote:
> Calling pm_runtime_get_sync() at driver's removal time is not
> needed, as this will resume PM runtime. Also, the PM runtime
> code at pm_runtime_disable() already calls it, if it detects
> the need.
> 
> So, simplify the code by getting rid of that.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
>  drivers/media/platform/exynos-gsc/gsc-core.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/media/platform/exynos-gsc/gsc-core.c b/drivers/media/platform/exynos-gsc/gsc-core.c
> index 9f41c2e7097a..70e86cdc1012 100644
> --- a/drivers/media/platform/exynos-gsc/gsc-core.c
> +++ b/drivers/media/platform/exynos-gsc/gsc-core.c
> @@ -1210,8 +1210,6 @@ static int gsc_remove(struct platform_device *pdev)
>  	struct gsc_dev *gsc = platform_get_drvdata(pdev);
>  	int i;
>  
> -	pm_runtime_get_sync(&pdev->dev);
> -
>  	gsc_unregister_m2m_device(gsc);
>  	v4l2_device_unregister(&gsc->v4l2_dev);
>  
> @@ -1219,7 +1217,6 @@ 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);
>  	pm_runtime_disable(&pdev->dev);

This will result in unbalanced clk_disable_unprepare() calls when 
the device is not runtime PM active at the time of gsc_remove() call. 
I think we need to first disable runtime PM for the device and then 
disable the clocks only when pm_runtime_status_suspended(&pdev->dev)
returns false.


Thanks,
Sylwester