linux-kernel - Re: [PATCH v2 2/5] media: cadence: csi2rx: Add system PM support

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Message-ID: <26af0977-8e38-47d0-a521-c5b1e505d564@ideasonboard.com>
Date: Fri, 19 Jul 2024 13:28:41 +0300
From: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
To: Changhuang Liang <changhuang.liang@...rfivetech.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Maxime Ripard <mripard@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Hans Verkuil <hverkuil-cisco@...all.nl>
Cc: Jacopo Mondi <jacopo.mondi@...asonboard.com>,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Jack Zhu <jack.zhu@...rfivetech.com>,
 Keith Zhao <keith.zhao@...rfivetech.com>, Jayshri Pawar
 <jpawar@...ence.com>, Jai Luthra <j-luthra@...com>,
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-staging@...ts.linux.dev
Subject: Re: [PATCH v2 2/5] media: cadence: csi2rx: Add system PM support

Hi,

On 18/07/2024 06:28, Changhuang Liang wrote:
> Add system PM support make it stopping streaming at system suspend time,
> and restarting streaming at system resume time.
> 
> Signed-off-by: Changhuang Liang <changhuang.liang@...rfivetech.com>
> ---
>   drivers/media/platform/cadence/cdns-csi2rx.c | 32 ++++++++++++++++++++
>   1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 981819adbb3a..81e90b31e9f8 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -776,8 +776,40 @@ static int csi2rx_runtime_resume(struct device *dev)
>   	return ret;
>   }
>   
> +static int __maybe_unused csi2rx_suspend(struct device *dev)
> +{
> +	struct csi2rx_priv *csi2rx = dev_get_drvdata(dev);
> +
> +	mutex_lock(&csi2rx->lock);
> +	if (csi2rx->count)
> +		csi2rx_stop(csi2rx);
> +	mutex_unlock(&csi2rx->lock);
> +
> +	pm_runtime_force_suspend(dev);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused csi2rx_resume(struct device *dev)
> +{
> +	struct csi2rx_priv *csi2rx = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = pm_runtime_force_resume(dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_lock(&csi2rx->lock);
> +	if (csi2rx->count)
> +		csi2rx_start(csi2rx);
> +	mutex_unlock(&csi2rx->lock);
> +
> +	return 0;
> +}
> +
>   static const struct dev_pm_ops csi2rx_pm_ops = {
>   	SET_RUNTIME_PM_OPS(csi2rx_runtime_suspend, csi2rx_runtime_resume, NULL)
> +	SET_SYSTEM_SLEEP_PM_OPS(csi2rx_suspend, csi2rx_resume)
>   };
>   
>   static const struct of_device_id csi2rx_of_table[] = {

If I'm not mistaken, this is a subdev driver, and is somewhere in the 
middle of the pipeline. Afaiu, only the driver that handles the v4l2 
video devices should have system suspend hooks. The job of that driver 
is then to disable or enable the pipeline using v4l2 functions, and for 
the rest of the pipeline system suspend looks just like a normal 
pipeline disable.

  Tomi