linux-kernel - Re: [PATCH v3 78/79] media: rcar-vin: use pm_runtime_resume_and

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Date:   Tue, 27 Apr 2021 22:12:30 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v3 78/79] media: rcar-vin: use pm_runtime_resume_and_get()

Hi Mauro,

On 2021-04-27 12:27:08 +0200, 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.
> 
> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
>  drivers/media/platform/rcar-vin/rcar-csi2.c | 6 ++++++
>  drivers/media/platform/rcar-vin/rcar-dma.c  | 6 ++----
>  drivers/media/platform/rcar-vin/rcar-v4l2.c | 6 ++----
>  3 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index e06cd512aba2..ce8e84f9e3d9 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -408,6 +408,12 @@ static void rcsi2_enter_standby(struct rcar_csi2 *priv)
>  
>  static void rcsi2_exit_standby(struct rcar_csi2 *priv)
>  {
> +	/*
> +	 * The code at rcsi2_enter_standby() assumes
> +	 * inconditionally that PM runtime usage count was
> +	 * incremented. So, it shouldn't use pm_runtime_resume_and_get()
> +	 * here.
> +	 */

I think this comment is a bit much. I won't object if you really want to 
keep it but my preference would be to drop it.

>  	pm_runtime_get_sync(priv->dev);
>  	reset_control_deassert(priv->rstc);
>  }
> diff --git a/drivers/media/platform/rcar-vin/rcar-dma.c b/drivers/media/platform/rcar-vin/rcar-dma.c
> index f30dafbdf61c..f5f722ab1d4e 100644
> --- a/drivers/media/platform/rcar-vin/rcar-dma.c
> +++ b/drivers/media/platform/rcar-vin/rcar-dma.c
> @@ -1458,11 +1458,9 @@ int rvin_set_channel_routing(struct rvin_dev *vin, u8 chsel)
>  	u32 vnmc;
>  	int ret;
>  
> -	ret = pm_runtime_get_sync(vin->dev);
> -	if (ret < 0) {
> -		pm_runtime_put_noidle(vin->dev);
> +	ret = pm_runtime_resume_and_get(vin->dev);
> +	if (ret < 0)
>  		return ret;
> -	}
>  
>  	/* Make register writes take effect immediately. */
>  	vnmc = rvin_read(vin, VNMC_REG);
> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> index 457a65bf6b66..b1e9f86caa5c 100644
> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> @@ -870,11 +870,9 @@ static int rvin_open(struct file *file)
>  	struct rvin_dev *vin = video_drvdata(file);
>  	int ret;
>  
> -	ret = pm_runtime_get_sync(vin->dev);
> -	if (ret < 0) {
> -		pm_runtime_put_noidle(vin->dev);
> +	ret = pm_runtime_resume_and_get(vin->dev);
> +	if (ret < 0)
>  		return ret;
> -	}
>  
>  	ret = mutex_lock_interruptible(&vin->lock);
>  	if (ret)
> -- 
> 2.30.2
> 

-- 
Regards,
Niklas Söderlund