linux-kernel - Re: [PATCH v2 09/20] media: i2c: ov4689: Use runtime PM autosuspend

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Date: Mon, 8 Jan 2024 11:18:39 +0000
From: Sakari Ailus <sakari.ailus@....fi>
To: Mikhail Rudenko <mike.rudenko@...il.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Jacopo Mondi <jacopo@...ndi.org>,
	Tommaso Merciai <tomm.merciai@...il.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: Re: [PATCH v2 09/20] media: i2c: ov4689: Use runtime PM autosuspend

Hi Mikhail,

On Mon, Dec 18, 2023 at 08:40:30PM +0300, Mikhail Rudenko wrote:
> Use runtime PM autosuspend to avoid powering off the sensor during
> fast stop-reconfigure-restart cycles.
> 
> Signed-off-by: Mikhail Rudenko <mike.rudenko@...il.com>
> ---
>  drivers/media/i2c/ov4689.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov4689.c b/drivers/media/i2c/ov4689.c
> index 5300e621ff90..64cc6d9e48cc 100644
> --- a/drivers/media/i2c/ov4689.c
> +++ b/drivers/media/i2c/ov4689.c
> @@ -407,26 +407,27 @@ static int ov4689_s_stream(struct v4l2_subdev *sd, int on)
>  					  ov4689->cur_mode->num_regs,
>  					  NULL);
>  		if (ret) {
> -			pm_runtime_put(dev);
> +			pm_runtime_put_sync(dev);

Why are you switching to pm_runtime_put_sync() here? That isn't covered by
the commit message (nor I think should be done).

>  			goto unlock_and_return;
>  		}
>  
>  		ret = __v4l2_ctrl_handler_setup(&ov4689->ctrl_handler);
>  		if (ret) {
> -			pm_runtime_put(dev);
> +			pm_runtime_put_sync(dev);
>  			goto unlock_and_return;
>  		}
>  
>  		ret = cci_write(ov4689->regmap, OV4689_REG_CTRL_MODE,
>  				OV4689_MODE_STREAMING, NULL);
>  		if (ret) {
> -			pm_runtime_put(dev);
> +			pm_runtime_put_sync(dev);
>  			goto unlock_and_return;
>  		}
>  	} else {
>  		cci_write(ov4689->regmap, OV4689_REG_CTRL_MODE,
>  			  OV4689_MODE_SW_STANDBY, NULL);
> -		pm_runtime_put(dev);
> +		pm_runtime_mark_last_busy(dev);
> +		pm_runtime_put_autosuspend(dev);
>  	}
>  
>  unlock_and_return:
> @@ -606,7 +607,9 @@ static int ov4689_set_ctrl(struct v4l2_ctrl *ctrl)
>  		break;
>  	}
>  
> -	pm_runtime_put(dev);
> +	pm_runtime_mark_last_busy(dev);
> +	pm_runtime_put_autosuspend(dev);

Also note that with runtime PM autosuspend,  you have to use
pm_runtime_get_if_active() instead of pm_runtime_get_if_in_use().

> +
>  	return ret;
>  }
>  
> @@ -877,8 +880,10 @@ static int ov4689_probe(struct i2c_client *client)
>  	}
>  
>  	pm_runtime_set_active(dev);
> +	pm_runtime_get_noresume(dev);
>  	pm_runtime_enable(dev);
> -	pm_runtime_idle(dev);
> +	pm_runtime_set_autosuspend_delay(dev, 1000);
> +	pm_runtime_use_autosuspend(dev);
>  
>  	ret = v4l2_async_register_subdev_sensor(sd);
>  	if (ret) {
> @@ -886,11 +891,14 @@ static int ov4689_probe(struct i2c_client *client)
>  		goto err_clean_subdev_pm;
>  	}
>  
> +	pm_runtime_mark_last_busy(dev);
> +	pm_runtime_put_autosuspend(dev);
> +
>  	return 0;
>  
>  err_clean_subdev_pm:
>  	pm_runtime_disable(dev);
> -	pm_runtime_set_suspended(dev);
> +	pm_runtime_put_noidle(dev);
>  	v4l2_subdev_cleanup(sd);
>  err_clean_entity:
>  	media_entity_cleanup(&sd->entity);

-- 
Regards,

Sakari Ailus