Re: [PATCH v2] media: ov5640: Use runtime PM

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Fri, Mar 11, 2022 at 02:23:53PM +0200, Sakari Ailus wrote:
> On Fri, Mar 11, 2022 at 08:12:59PM +0900, Paul Elder wrote:
> > Switch to using runtime PM for power management.
> > 
> > Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
> > 
> > ---
> > Changes in v2:
> > - replace manual tracking of power status with pm_runtime_get_if_in_use
> > - power on the sensor before reading the checking the chip id
> > - add dependency on PM to Kconfig
> > ---
> >  drivers/media/i2c/Kconfig  |   1 +
> >  drivers/media/i2c/ov5640.c | 112 ++++++++++++++++++++++---------------
> >  2 files changed, 67 insertions(+), 46 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > index e7194c1be4d2..97c3611d9304 100644
> > --- a/drivers/media/i2c/Kconfig
> > +++ b/drivers/media/i2c/Kconfig
> > @@ -1025,6 +1025,7 @@ config VIDEO_OV5640
> >  	tristate "OmniVision OV5640 sensor support"
> >  	depends on OF
> >  	depends on GPIOLIB && VIDEO_V4L2 && I2C
> > +	depends on PM
> 
> I think this is not needed as the sensor is powered on explicitly in probe.
> 
> You should similarly power it off explicitly in remove, set the runtime PM
> status suspended and disable runtime PM. See e.g. imx319 driver for an
> example. It doesn't have resume callback but that doesn't really matter ---
> it's just ACPI-only.

Do we want to continue supporting !PM ? Does it have any real use case
when dealing with camera sensors ?

> >  	select MEDIA_CONTROLLER
> >  	select VIDEO_V4L2_SUBDEV_API
> >  	select V4L2_FWNODE
> > diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> > index 4de83d0ef85d..454ffd3c6d59 100644
> > --- a/drivers/media/i2c/ov5640.c
> > +++ b/drivers/media/i2c/ov5640.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/init.h>
> >  #include <linux/module.h>
> >  #include <linux/of_device.h>
> > +#include <linux/pm_runtime.h>
> >  #include <linux/regulator/consumer.h>
> >  #include <linux/slab.h>
> >  #include <linux/types.h>
> > @@ -445,8 +446,6 @@ struct ov5640_dev {
> >  	/* lock to protect all members below */
> >  	struct mutex lock;
> >  
> > -	int power_count;
> > -
> >  	struct v4l2_mbus_framefmt fmt;
> >  	bool pending_fmt_change;
> >  
> > @@ -2693,37 +2692,6 @@ static int ov5640_set_power(struct ov5640_dev *sensor, bool on)
> >  
> >  /* --------------- Subdev Operations --------------- */
> >  
> > -static int ov5640_s_power(struct v4l2_subdev *sd, int on)
> > -{
> > -	struct ov5640_dev *sensor = to_ov5640_dev(sd);
> > -	int ret = 0;
> > -
> > -	mutex_lock(&sensor->lock);
> > -
> > -	/*
> > -	 * If the power count is modified from 0 to != 0 or from != 0 to 0,
> > -	 * update the power state.
> > -	 */
> > -	if (sensor->power_count == !on) {
> > -		ret = ov5640_set_power(sensor, !!on);
> > -		if (ret)
> > -			goto out;
> > -	}
> > -
> > -	/* Update the power count. */
> > -	sensor->power_count += on ? 1 : -1;
> > -	WARN_ON(sensor->power_count < 0);
> > -out:
> > -	mutex_unlock(&sensor->lock);
> > -
> > -	if (on && !ret && sensor->power_count == 1) {
> > -		/* restore controls */
> > -		ret = v4l2_ctrl_handler_setup(&sensor->ctrls.handler);
> > -	}
> > -
> > -	return ret;
> > -}
> > -
> >  static int ov5640_try_frame_interval(struct ov5640_dev *sensor,
> >  				     struct v4l2_fract *fi,
> >  				     u32 width, u32 height)
> > @@ -3288,6 +3256,9 @@ static int ov5640_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
> >  
> >  	/* v4l2_ctrl_lock() locks our own mutex */
> >  
> > +	if (!pm_runtime_get_if_in_use(&sensor->i2c_client->dev))
> > +		return 0;
> > +
> >  	switch (ctrl->id) {
> >  	case V4L2_CID_AUTOGAIN:
> >  		val = ov5640_get_gain(sensor);
> > @@ -3303,6 +3274,8 @@ static int ov5640_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
> >  		break;
> >  	}
> >  
> > +	pm_runtime_put_autosuspend(&sensor->i2c_client->dev);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -3334,7 +3307,7 @@ static int ov5640_s_ctrl(struct v4l2_ctrl *ctrl)
> >  	 * not apply any controls to H/W at this time. Instead
> >  	 * the controls will be restored right after power-up.
> >  	 */
> > -	if (sensor->power_count == 0)
> > +	if (!pm_runtime_get_if_in_use(&sensor->i2c_client->dev))
> >  		return 0;
> >  
> >  	switch (ctrl->id) {
> > @@ -3376,6 +3349,8 @@ static int ov5640_s_ctrl(struct v4l2_ctrl *ctrl)
> >  		break;
> >  	}
> >  
> > +	pm_runtime_put_autosuspend(&sensor->i2c_client->dev);
> > +
> >  	return ret;
> >  }
> >  
> > @@ -3657,6 +3632,12 @@ static int ov5640_s_stream(struct v4l2_subdev *sd, int enable)
> >  	struct ov5640_dev *sensor = to_ov5640_dev(sd);
> >  	int ret = 0;
> >  
> > +	if (enable) {
> > +		ret = pm_runtime_resume_and_get(&sensor->i2c_client->dev);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> >  	mutex_lock(&sensor->lock);
> >  
> >  	if (sensor->streaming == !enable) {
> > @@ -3681,8 +3662,13 @@ static int ov5640_s_stream(struct v4l2_subdev *sd, int enable)
> >  		if (!ret)
> >  			sensor->streaming = enable;
> >  	}
> > +
> >  out:
> >  	mutex_unlock(&sensor->lock);
> > +
> > +	if (!enable || ret)
> > +		pm_runtime_put(&sensor->i2c_client->dev);
> > +
> >  	return ret;
> >  }
> >  
> > @@ -3704,7 +3690,6 @@ static int ov5640_init_cfg(struct v4l2_subdev *sd,
> >  }
> >  
> >  static const struct v4l2_subdev_core_ops ov5640_core_ops = {
> > -	.s_power = ov5640_s_power,
> >  	.log_status = v4l2_ctrl_subdev_log_status,
> >  	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> >  	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
> > @@ -3750,15 +3735,11 @@ static int ov5640_check_chip_id(struct ov5640_dev *sensor)
> >  	int ret = 0;
> >  	u16 chip_id;
> >  
> > -	ret = ov5640_set_power_on(sensor);
> > -	if (ret)
> > -		return ret;
> > -
> >  	ret = ov5640_read_reg16(sensor, OV5640_REG_CHIP_ID, &chip_id);
> >  	if (ret) {
> >  		dev_err(&client->dev, "%s: failed to read chip identifier\n",
> >  			__func__);
> > -		goto power_off;
> > +		return ret;
> >  	}
> >  
> >  	if (chip_id != 0x5640) {
> > @@ -3767,8 +3748,6 @@ static int ov5640_check_chip_id(struct ov5640_dev *sensor)
> >  		ret = -ENXIO;
> >  	}
> >  
> > -power_off:
> > -	ov5640_set_power_off(sensor);
> >  	return ret;
> >  }
> >  
> > @@ -3863,20 +3842,35 @@ static int ov5640_probe(struct i2c_client *client)
> >  
> >  	mutex_init(&sensor->lock);
> >  
> > -	ret = ov5640_check_chip_id(sensor);
> > +	ret = ov5640_init_controls(sensor);
> >  	if (ret)
> >  		goto entity_cleanup;
> >  
> > -	ret = ov5640_init_controls(sensor);
> > +	ret = ov5640_set_power(sensor, true);
> >  	if (ret)
> > -		goto entity_cleanup;
> > +		goto free_ctrls;
> > +
> > +	pm_runtime_set_active(dev);
> > +	pm_runtime_enable(dev);
> > +	pm_runtime_get(dev);
> > +
> > +	ret = ov5640_check_chip_id(sensor);
> > +	if (ret)
> > +		goto err_pm_runtime;
> >  
> >  	ret = v4l2_async_register_subdev_sensor(&sensor->sd);
> >  	if (ret)
> > -		goto free_ctrls;
> > +		goto err_pm_runtime;
> > +
> > +	pm_runtime_set_autosuspend_delay(dev, 1000);
> > +	pm_runtime_use_autosuspend(dev);
> > +	pm_runtime_put_autosuspend(dev);
> >  
> >  	return 0;
> >  
> > +err_pm_runtime:
> > +	pm_runtime_disable(dev);
> > +	pm_runtime_put_noidle(dev);
> >  free_ctrls:
> >  	v4l2_ctrl_handler_free(&sensor->ctrls.handler);
> >  entity_cleanup:
> > @@ -3898,6 +3892,31 @@ static int ov5640_remove(struct i2c_client *client)
> >  	return 0;
> >  }
> >  
> > +static int __maybe_unused ov5640_sensor_suspend(struct device *dev)
> > +{
> > +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > +	struct ov5640_dev *ov5640 = to_ov5640_dev(sd);
> > +
> > +	return ov5640_set_power(ov5640, false);
> > +}
> > +
> > +static int __maybe_unused ov5640_sensor_resume(struct device *dev)
> > +{
> > +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > +	struct ov5640_dev *ov5640 = to_ov5640_dev(sd);
> > +	int ret;
> > +
> > +	ret = ov5640_set_power(ov5640, true);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return v4l2_ctrl_handler_setup(&ov5640->ctrls.handler);
> > +}
> > +
> > +static const struct dev_pm_ops ov5640_pm_ops = {
> > +	SET_RUNTIME_PM_OPS(ov5640_sensor_suspend, ov5640_sensor_resume, NULL)
> > +};
> > +
> >  static const struct i2c_device_id ov5640_id[] = {
> >  	{"ov5640", 0},
> >  	{},
> > @@ -3914,6 +3933,7 @@ static struct i2c_driver ov5640_i2c_driver = {
> >  	.driver = {
> >  		.name  = "ov5640",
> >  		.of_match_table	= ov5640_dt_ids,
> > +		.pm = &ov5640_pm_ops,
> >  	},
> >  	.id_table = ov5640_id,
> >  	.probe_new = ov5640_probe,
> 
> -- 
> Kind regards,
> 
> Sakari Ailus

-- 
Regards,

Laurent Pinchart