Re: [PATCH v4 1/1] cap11xx: add runtime PM support

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Matt,

On Sun, Aug 23, 2015 at 02:17:57PM -0700, Matt Ranostay wrote:
> Puts device into DEEP SLEEP when no LEDs are in in the on-state, and no
> input_handlers are in use. Also uses *_autosuspend to prevent a LED
> trigger from constantly suspending and resuming device.
> 
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
> ---
>  drivers/input/keyboard/cap11xx.c | 84 +++++++++++++++++++++++++++++++---------
>  1 file changed, 65 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c
> index 378db10..13fae03 100644
> --- a/drivers/input/keyboard/cap11xx.c
> +++ b/drivers/input/keyboard/cap11xx.c
> @@ -14,6 +14,7 @@
>  #include <linux/input.h>
>  #include <linux/leds.h>
>  #include <linux/of_irq.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
>  #include <linux/i2c.h>
>  #include <linux/gpio/consumer.h>
> @@ -84,9 +85,9 @@ struct cap11xx_led {
>  struct cap11xx_priv {
>  	struct regmap *regmap;
>  	struct input_dev *idev;
> +	struct i2c_client *i2c_client;
>  
>  	struct cap11xx_led *leds;
> -	int num_leds;
>  
>  	/* config */
>  	u32 keycodes[];
> @@ -207,12 +208,6 @@ out:
>  
>  static int cap11xx_set_sleep(struct cap11xx_priv *priv, bool sleep)
>  {
> -	/*
> -	 * DLSEEP mode will turn off all LEDS, prevent this
> -	 */
> -	if (IS_ENABLED(CONFIG_LEDS_CLASS) && priv->num_leds)
> -		return 0;
> -
>  	return regmap_update_bits(priv->regmap, CAP11XX_REG_MAIN_CONTROL,
>  				  CAP11XX_REG_MAIN_CONTROL_DLSEEP,
>  				  sleep ? CAP11XX_REG_MAIN_CONTROL_DLSEEP : 0);
> @@ -222,14 +217,16 @@ static int cap11xx_input_open(struct input_dev *idev)
>  {
>  	struct cap11xx_priv *priv = input_get_drvdata(idev);
>  
> -	return cap11xx_set_sleep(priv, false);
> +	pm_runtime_get(&priv->i2c_client->dev);
> +
> +	return 0;
>  }
>  
>  static void cap11xx_input_close(struct input_dev *idev)
>  {
>  	struct cap11xx_priv *priv = input_get_drvdata(idev);
>  
> -	cap11xx_set_sleep(priv, true);
> +	pm_runtime_put_autosuspend(&priv->i2c_client->dev);
>  }
>  
>  #ifdef CONFIG_LEDS_CLASS
> @@ -251,10 +248,16 @@ static void cap11xx_led_set(struct led_classdev *cdev,
>  			   enum led_brightness value)
>  {
>  	struct cap11xx_led *led = container_of(cdev, struct cap11xx_led, cdev);
> +	struct cap11xx_priv *priv = led->priv;
>  
>  	if (led->new_brightness == value)
>  		return;
>  
> +	if (value)
> +		pm_runtime_get(&priv->i2c_client->dev);
> +	else
> +		pm_runtime_put_autosuspend(&priv->i2c_client->dev);
> +

IIRC cap11xx_led_set() can not sleep (that is why we use workqueue to
actually toggle the led) so I do not think that you can call
pm_runtime_get() here, as it is likely to involve sleep as well.

I also wonder if there is a race between PM state that you set here and
work item trying to access device state.

I'd look into moving PM handling into work function.

>  	led->new_brightness = value;
>  	schedule_work(&led->work);
>  }
> @@ -315,8 +318,6 @@ static int cap11xx_init_leds(struct device *dev,
>  		error = devm_led_classdev_register(dev, &led->cdev);
>  		if (error)
>  			return error;
> -
> -		priv->num_leds++;
>  		led++;
>  	}
>  
> @@ -330,6 +331,16 @@ static int cap11xx_init_leds(struct device *dev,
>  }
>  #endif
>  
> +static void cap11xx_shutdown_act(void *data)
> +{
> +	struct i2c_client *i2c_client = data;
> +	struct cap11xx_priv *priv = i2c_get_clientdata(i2c_client);
> +
> +	cap11xx_set_sleep(priv, true);
> +	pm_runtime_disable(&i2c_client->dev);
> +	pm_runtime_set_suspended(&i2c_client->dev);
> +}
> +
>  static int cap11xx_i2c_probe(struct i2c_client *i2c_client,
>  			     const struct i2c_device_id *id)
>  {
> @@ -363,6 +374,14 @@ static int cap11xx_i2c_probe(struct i2c_client *i2c_client,
>  	if (IS_ERR(priv->regmap))
>  		return PTR_ERR(priv->regmap);
>  
> +	error = devm_add_action(dev, cap11xx_shutdown_act, i2c_client);
> +	if (error) {
> +		dev_err(dev, "failed to register remove action\n");
> +		return error;
> +	}
> +	i2c_set_clientdata(i2c_client, priv);
> +	priv->i2c_client = i2c_client;
> +
>  	error = regmap_read(priv->regmap, CAP11XX_REG_PRODUCT_ID, &val);
>  	if (error)
>  		return error;
> @@ -388,7 +407,6 @@ static int cap11xx_i2c_probe(struct i2c_client *i2c_client,
>  		return error;
>  
>  	dev_info(dev, "CAP11XX detected, revision 0x%02x\n", rev);
> -	i2c_set_clientdata(i2c_client, priv);
>  	node = dev->of_node;
>  
>  	if (!of_property_read_u32(node, "microchip,sensor-gain", &gain32)) {
> @@ -450,22 +468,28 @@ static int cap11xx_i2c_probe(struct i2c_client *i2c_client,
>  	priv->idev->open = cap11xx_input_open;
>  	priv->idev->close = cap11xx_input_close;
>  
> -	error = cap11xx_init_leds(dev, priv, cap->num_leds);
> +	error = cap11xx_set_sleep(priv, true);
>  	if (error)
>  		return error;
>  
> -	input_set_drvdata(priv->idev, priv);
> +	error = pm_runtime_set_active(dev);

I am confused - we put device to sleep above and then declare it active?

> +	if (error)
> +		return error;
>  
> -	/*
> -	 * Put the device in deep sleep mode for now.
> -	 * ->open() will bring it back once the it is actually needed.
> -	 */
> -	cap11xx_set_sleep(priv, true);
> +	pm_runtime_enable(dev);
> +	pm_runtime_set_autosuspend_delay(dev, 1000);
> +	pm_runtime_use_autosuspend(dev);
> +
> +	input_set_drvdata(priv->idev, priv);
>  
>  	error = input_register_device(priv->idev);
>  	if (error)
>  		return error;
>  
> +	error = cap11xx_init_leds(dev, priv, cap->num_leds);
> +	if (error)
> +		return error;
> +
>  	irq = irq_of_parse_and_map(node, 0);
>  	if (!irq) {
>  		dev_err(dev, "Unable to parse or map IRQ\n");
> @@ -496,10 +520,32 @@ static const struct i2c_device_id cap11xx_i2c_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, cap11xx_i2c_ids);
>  
> +#ifdef CONFIG_PM
> +static int cap11xx_runtime_suspend(struct device *dev)

__maybe_unused instead of #ifdef please.

> +{
> +	struct cap11xx_priv *priv = i2c_get_clientdata(to_i2c_client(dev));
> +
> +	return cap11xx_set_sleep(priv, true);
> +}
> +
> +static int cap11xx_runtime_resume(struct device *dev)
> +{
> +	struct cap11xx_priv *priv = i2c_get_clientdata(to_i2c_client(dev));
> +
> +	return cap11xx_set_sleep(priv, false);
> +}
> +#endif
> +
> +static const struct dev_pm_ops cap11xx_pm_ops = {
> +	SET_RUNTIME_PM_OPS(cap11xx_runtime_suspend,
> +			   cap11xx_runtime_resume, NULL)
> +};
> +
>  static struct i2c_driver cap11xx_i2c_driver = {
>  	.driver = {
>  		.name	= "cap11xx",
>  		.of_match_table = cap11xx_dt_ids,
> +		.pm	= &cap11xx_pm_ops,
>  	},
>  	.id_table	= cap11xx_i2c_ids,
>  	.probe		= cap11xx_i2c_probe,
> -- 
> 1.9.1
> 

Thanks.

-- 
Dmitry