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

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Message-ID: <87edd0d1pq.fsf@gmail.com>
Date: Sun, 25 Feb 2024 17:58:43 +0300
From: Mikhail Rudenko <mike.rudenko@...il.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Sakari Ailus <sakari.ailus@....fi>, linux-media@...r.kernel.org,
 linux-kernel@...r.kernel.org, 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


On 2024-02-24 at 19:38 GMT, Sakari Ailus <sakari.ailus@...ux.intel.com> wrote:

> Hi Mikhail,
>
> On Fri, Feb 23, 2024 at 06:18:12PM +0300, Mikhail Rudenko wrote:
>>
>> Hi Sakari,
>>
>> and thanks for the review!
>>
>> On 2024-02-23 at 08:19 GMT, Sakari Ailus <sakari.ailus@...ux.intel.com> wrote:
>>
>> > Hi Mikhail,
>> >
>> > On Mon, Jan 08, 2024 at 06:06:52PM +0300, Mikhail Rudenko wrote:
>> >> 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].
>> >
>> > There's no need to use the _sync() variant here. And at least it wouldn't
>> > be related to autosuspend, were you to switch to that.
>>
>> Ok, will use pm_runtime_put in v3. Or do you suggest dropping this patch
>> altogether? Laurent?
>
> Using autosuspend is preferred.
>
> Much of the benefit come from avoiding redundant register writes but that's
> a separate matter.

I see, will try to do it in a separate patch outside this series. Could
you please point to a driver which does this right?

>
>>
>> >>
>> >> >>  			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