linux-kernel - Re: [PATCH v4 16/79] media: mtk-vcodec: fix pm_runtime_get

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Message-ID: <20210430174413.0000452c@Huawei.com>
Date:   Fri, 30 Apr 2021 17:44:13 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
CC:     <linuxarm@...wei.com>, <mauro.chehab@...wei.com>,
        Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v4 16/79] media: mtk-vcodec: fix pm_runtime_get_sync()
 usage count

On Wed, 28 Apr 2021 16:51:37 +0200
Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:

> The pm_runtime_get_sync() internally increments the
> dev->power.usage_count without decrementing it, even on errors.
> 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")
> in order to properly decrement the usage counter and avoid memory
> leaks.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Without a return value, this seems like it's not complete as driver
will carry on and eventually call mtk_vcode_dec_pw_off() which will assume
it needs to decrement the count.


> ---
>  drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_pm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_pm.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_pm.c
> index ddee7046ce42..fe096fe61c9d 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_pm.c
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_pm.c
> @@ -92,9 +92,9 @@ void mtk_vcodec_dec_pw_on(struct mtk_vcodec_pm *pm)
>  {
>  	int ret;
>  
> -	ret = pm_runtime_get_sync(pm->dev);
> +	ret = pm_runtime_resume_and_get(pm->dev);
>  	if (ret)
> -		mtk_v4l2_err("pm_runtime_get_sync fail %d", ret);
> +		mtk_v4l2_err("pm_runtime_resume_and_get fail %d", ret);
>  }
>  
>  void mtk_vcodec_dec_pw_off(struct mtk_vcodec_pm *pm)