Re: [PATCH v2 14/17] media: i2c: imx290: Initialize runtime PM before subdev

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

Hi Alexander,

On Mon, Jan 16, 2023 at 12:14:46PM +0100, Alexander Stein wrote:
> Am Samstag, 14. Januar 2023, 18:17:59 CET schrieb Laurent Pinchart:
> > Initializing the subdev before runtime PM means that no subdev
> > initialization can interact with the runtime PM framework. This can be
> > problematic when modifying controls, as the .s_ctrl() handler commonly
> > calls pm_runtime_get_if_in_use(). These code paths are not trivial,
> > making the driver fragile and possibly causing subtle bugs.
> > 
> > To make the subdev initialization more robust, initialize runtime PM
> > first.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thank you for giving me my own ack, but yours would be more useful :-)

> > ---
> >  drivers/media/i2c/imx290.c | 57 ++++++++++++++++++++++----------------
> >  1 file changed, 33 insertions(+), 24 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> > index 6a3e93c10fb1..c3ffb23104bf 100644
> > --- a/drivers/media/i2c/imx290.c
> > +++ b/drivers/media/i2c/imx290.c
> > @@ -581,9 +581,7 @@ static int imx290_set_ctrl(struct v4l2_ctrl *ctrl)
> > 
> >  	/*
> >  	 * Return immediately for controls that don't need to be applied to the
> > -	 * device. This includes all controls modified in imx290_ctrl_update(),
> > -	 * which is called at probe time before runtime PM is initialized, so
> > -	 * we can't proceed to the pm_runtime_get_if_in_use() call below.
> > +	 * device.
> >  	 */
> >  	switch (ctrl->id) {
> >  	case V4L2_CID_LINK_FREQ:
> > @@ -1054,22 +1052,20 @@ static void imx290_subdev_cleanup(struct imx290 *imx290)
> >   * Power management
> >   */
> > 
> > -static int imx290_power_on(struct device *dev)
> > +static int imx290_power_on(struct imx290 *imx290)
> >  {
> > -	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > -	struct imx290 *imx290 = to_imx290(sd);
> >  	int ret;
> > 
> >  	ret = clk_prepare_enable(imx290->xclk);
> >  	if (ret) {
> > -		dev_err(dev, "Failed to enable clock\n");
> > +		dev_err(imx290->dev, "Failed to enable clock\n");
> >  		return ret;
> >  	}
> > 
> >  	ret = regulator_bulk_enable(ARRAY_SIZE(imx290->supplies),
> >  				    imx290->supplies);
> >  	if (ret) {
> > -		dev_err(dev, "Failed to enable regulators\n");
> > +		dev_err(imx290->dev, "Failed to enable regulators\n");
> >  		clk_disable_unprepare(imx290->xclk);
> >  		return ret;
> >  	}
> > @@ -1084,20 +1080,33 @@ static int imx290_power_on(struct device *dev)
> >  	return 0;
> >  }
> > 
> > -static int imx290_power_off(struct device *dev)
> > +static void imx290_power_off(struct imx290 *imx290)
> >  {
> > -	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > -	struct imx290 *imx290 = to_imx290(sd);
> > -
> >  	clk_disable_unprepare(imx290->xclk);
> >  	gpiod_set_value_cansleep(imx290->rst_gpio, 1);
> >  	regulator_bulk_disable(ARRAY_SIZE(imx290->supplies), imx290->supplies);
> > +}
> > +
> > +static int imx290_runtime_resume(struct device *dev)
> > +{
> > +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > +	struct imx290 *imx290 = to_imx290(sd);
> > +
> > +	return imx290_power_on(imx290);
> > +}
> > +
> > +static int imx290_runtime_suspend(struct device *dev)
> > +{
> > +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> > +	struct imx290 *imx290 = to_imx290(sd);
> > +
> > +	imx290_power_off(imx290);
> > 
> >  	return 0;
> >  }
> > 
> >  static const struct dev_pm_ops imx290_pm_ops = {
> > -	SET_RUNTIME_PM_OPS(imx290_power_off, imx290_power_on, NULL)
> > +	SET_RUNTIME_PM_OPS(imx290_runtime_suspend, imx290_runtime_resume, NULL)
> >  };
> > 
> >  /* ----------------------------------------------------------------------------
> > @@ -1276,20 +1285,15 @@ static int imx290_probe(struct i2c_client *client)
> > if (ret)
> >  		return ret;
> > 
> > -	/* Initialize the V4L2 subdev. */
> > -	ret = imx290_subdev_init(imx290);
> > -	if (ret)
> > -		return ret;
> > -
> >  	/*
> >  	 * Enable power management. The driver supports runtime PM, but needs to
> >  	 * work when runtime PM is disabled in the kernel. To that end, power
> >  	 * the sensor on manually here.
> >  	 */
> > -	ret = imx290_power_on(dev);
> > +	ret = imx290_power_on(imx290);
> >  	if (ret < 0) {
> >  		dev_err(dev, "Could not power on the device\n");
> > -		goto err_subdev;
> > +		return ret;
> >  	}
> > 
> >  	/*
> > @@ -1303,6 +1307,11 @@ static int imx290_probe(struct i2c_client *client)
> >  	pm_runtime_set_autosuspend_delay(dev, 1000);
> >  	pm_runtime_use_autosuspend(dev);
> > 
> > +	/* Initialize the V4L2 subdev. */
> > +	ret = imx290_subdev_init(imx290);
> > +	if (ret)
> > +		goto err_pm;
> > +
> >  	/*
> >  	 * Finally, register the V4L2 subdev. This must be done after
> >  	 * initializing everything as the subdev can be used immediately after
> > @@ -1323,12 +1332,12 @@ static int imx290_probe(struct i2c_client *client)
> > 
> >  	return 0;
> > 
> > +err_subdev:
> > +	imx290_subdev_cleanup(imx290);
> >  err_pm:
> >  	pm_runtime_disable(dev);
> >  	pm_runtime_put_noidle(dev);
> > -	imx290_power_off(dev);
> > -err_subdev:
> > -	imx290_subdev_cleanup(imx290);
> > +	imx290_power_off(imx290);
> >  	return ret;
> >  }
> > 
> > @@ -1346,7 +1355,7 @@ static void imx290_remove(struct i2c_client *client)
> >  	 */
> >  	pm_runtime_disable(imx290->dev);
> >  	if (!pm_runtime_status_suspended(imx290->dev))
> > -		imx290_power_off(imx290->dev);
> > +		imx290_power_off(imx290);
> >  	pm_runtime_set_suspended(imx290->dev);
> >  }

-- 
Regards,

Laurent Pinchart