Re: [PATCH v3 6/8] media: i2c: ov5670: Add runtime_pm operations

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Jacopo,

On Tue, Mar 29, 2022 at 11:01:31AM +0200, Jacopo Mondi wrote:
> Implement the power up and power down routines and install them as
> runtime_pm handler for runtime_suspend and runtime_resume operations.
> 
> Rework the runtime_pm enablement and the chip power handling during
> probe, as calling pm_runtime_idle() in a driver that registers no
> idle callback is a nop.

The suspend callback is called by rpm_idle() in the absence of the
idle callback.

> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>  drivers/media/i2c/ov5670.c | 58 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 52 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5670.c b/drivers/media/i2c/ov5670.c
> index 9e69b4008917..b63b07d8ca2f 100644
> --- a/drivers/media/i2c/ov5670.c
> +++ b/drivers/media/i2c/ov5670.c
> @@ -4,6 +4,7 @@
>  #include <linux/acpi.h>
>  #include <linux/clk.h>
>  #include <linux/gpio/consumer.h>
> +#include <linux/delay.h>
>  #include <linux/i2c.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/module.h>
> @@ -2424,6 +2425,39 @@ static int ov5670_set_stream(struct v4l2_subdev *sd, int enable)
>  	return ret;
>  }
>  
> +static int __maybe_unused ov5670_runtime_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct ov5670 *ov5670 = to_ov5670(sd);
> +	int ret;
> +
> +	ret = regulator_bulk_enable(OV5670_NUM_SUPPLIES, ov5670->supplies);
> +	if (ret)
> +		return ret;
> +
> +	gpiod_set_value_cansleep(ov5670->pwdn_gpio, 0);
> +	gpiod_set_value_cansleep(ov5670->reset_gpio, 0);
> +
> +	/* 8192 * 2 clock pulses before the first SCCB transaction. */
> +	usleep_range(1000, 1500);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused ov5670_runtime_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct ov5670 *ov5670 = to_ov5670(sd);
> +
> +	gpiod_set_value_cansleep(ov5670->reset_gpio, 1);
> +	gpiod_set_value_cansleep(ov5670->pwdn_gpio, 1);
> +	regulator_bulk_disable(OV5670_NUM_SUPPLIES, ov5670->supplies);
> +
> +	return 0;
> +}
> +
>  static int __maybe_unused ov5670_suspend(struct device *dev)
>  {
>  	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> @@ -2564,14 +2598,25 @@ static int ov5670_probe(struct i2c_client *client)
>  		goto error_print;
>  	}
>  
> +	pm_runtime_enable(&client->dev);
> +
>  	full_power = acpi_dev_state_d0(&client->dev);
>  	if (full_power) {
> +		ret = pm_runtime_resume_and_get(&client->dev);

Please see how e.g. the CCS driver does this (no need for autosuspend
though). E.g. don't use runtime PM to power the sensor on in probe, or off
in remove.

> +		if (ret) {
> +			err_msg = "Failed to power on";
> +			goto error_print;
> +		}
> +
>  		/* Check module identity */
>  		ret = ov5670_identify_module(ov5670);
>  		if (ret) {
>  			err_msg = "ov5670_identify_module() error";
> -			goto error_print;
> +			goto error_power_off;
>  		}
> +
> +		/* Set the device's state to active if it's in D0 state. */
> +		pm_runtime_set_active(&client->dev);
>  	}
>  
>  	mutex_init(&ov5670->mutex);
> @@ -2608,11 +2653,7 @@ static int ov5670_probe(struct i2c_client *client)
>  
>  	ov5670->streaming = false;
>  
> -	/* Set the device's state to active if it's in D0 state. */
> -	if (full_power)
> -		pm_runtime_set_active(&client->dev);
> -	pm_runtime_enable(&client->dev);
> -	pm_runtime_idle(&client->dev);
> +	pm_runtime_suspend(&client->dev);
>  
>  	return 0;
>  
> @@ -2625,6 +2666,9 @@ static int ov5670_probe(struct i2c_client *client)
>  error_mutex_destroy:
>  	mutex_destroy(&ov5670->mutex);
>  
> +error_power_off:
> +	pm_runtime_put(&client->dev);
> +
>  error_print:
>  	dev_err(&client->dev, "%s: %s %d\n", __func__, err_msg, ret);
>  
> @@ -2641,6 +2685,7 @@ static int ov5670_remove(struct i2c_client *client)
>  	v4l2_ctrl_handler_free(sd->ctrl_handler);
>  	mutex_destroy(&ov5670->mutex);
>  
> +	pm_runtime_put(&client->dev);
>  	pm_runtime_disable(&client->dev);
>  
>  	return 0;
> @@ -2648,6 +2693,7 @@ static int ov5670_remove(struct i2c_client *client)
>  
>  static const struct dev_pm_ops ov5670_pm_ops = {
>  	SET_SYSTEM_SLEEP_PM_OPS(ov5670_suspend, ov5670_resume)
> +	SET_RUNTIME_PM_OPS(ov5670_runtime_suspend, ov5670_runtime_resume, NULL)
>  };
>  
>  #ifdef CONFIG_ACPI

-- 
Kind regards,

Sakari Ailus