linux-kernel - Re: [PATCH 2/3] media: i2c: imx219: Serialize during stream start/stop

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Message-ID: <YEi+FBRbXBJch1DM@pendragon.ideasonboard.com>
Date:   Wed, 10 Mar 2021 14:39:48 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Pavel Machek <pavel@...x.de>,
        Andrey Konovalov <andrey.konovalov@...aro.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Jacopo Mondi <jacopo@...ndi.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Prabhakar <prabhakar.csengg@...il.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH 2/3] media: i2c: imx219: Serialize during stream
 start/stop

Hi Prabhakar,

Thank you for the patch.

On Wed, Mar 10, 2021 at 12:20:13PM +0000, Lad Prabhakar wrote:
> Serialize during stream start/stop in suspend/resume callbacks.

Could you please explain why this is needed ?

> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/media/i2c/imx219.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index f0cf1985a4dc..87c021de1460 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -1172,8 +1172,10 @@ static int __maybe_unused imx219_suspend(struct device *dev)
>  	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>  	struct imx219 *imx219 = to_imx219(sd);
>  
> +	mutex_lock(&imx219->mutex);
>  	if (imx219->streaming)
>  		imx219_stop_streaming(imx219);
> +	mutex_unlock(&imx219->mutex);
>  
>  	return 0;
>  }
> @@ -1184,11 +1186,13 @@ static int __maybe_unused imx219_resume(struct device *dev)
>  	struct imx219 *imx219 = to_imx219(sd);
>  	int ret;
>  
> +	mutex_lock(&imx219->mutex);
>  	if (imx219->streaming) {
>  		ret = imx219_start_streaming(imx219);
>  		if (ret)
>  			goto error;
>  	}
> +	mutex_unlock(&imx219->mutex);
>  
>  	return 0;
>  
> @@ -1197,6 +1201,7 @@ static int __maybe_unused imx219_resume(struct device *dev)
>  	imx219->streaming = false;
>  	__v4l2_ctrl_grab(imx219->vflip, false);
>  	__v4l2_ctrl_grab(imx219->hflip, false);
> +	mutex_unlock(&imx219->mutex);
>  
>  	return ret;
>  }

-- 
Regards,

Laurent Pinchart