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

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Date: Mon, 08 Jan 2024 18:06:52 +0300
From: Mikhail Rudenko <mike.rudenko@...il.com>
To: Sakari Ailus <sakari.ailus@....fi>
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 Sakari,

Thanks for the review!

On 2024-01-08 at 11:18 GMT, Sakari Ailus <sakari.ailus@....fi> wrote:

> 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).

PM autosuspend conversion was suggested earlier by Laurent in his review
of this series [1], and he adviced looking at how it was done for the
imx290 driver. I followed along the lines of the corresponding patch
[2].

>>  			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().

Noted, will do so in v3.

>> +
>>  	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);

[1] https://lore.kernel.org/all/20231211181935.GG27535@pendragon.ideasonboard.com/
[2] https://lore.kernel.org/all/20230116144454.1012-14-laurent.pinchart@ideasonboard.com/

--
Best regards,
Mikhail Rudenko