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

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Laurent,

thanks for the update.

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>

> ---
>  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);
>  }