Date:   Sat, 21 Jan 2017 14:58:12 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Brian Masney <masneyb@...tation.org>, linux-iio@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        linux-kernel@...r.kernel.org, ldewangan@...dia.com
Subject: Re: [PATCH v2 15/15] staging: iio: isl29028: add runtime power
 management support

On 17/01/17 09:25, Brian Masney wrote:
> This patch adds runtime power management support to the isl29028 driver.
> It defaults to powering off the device after two seconds of inactivity.
> 
> isl29028_chip_init_and_power_on() currently only zeros the CONFIGURE
> register on the chip, which will cause the chip to turn off. This patch
> also renames that function to isl29028_clear_configure_reg() since it is
> now used in several places.
> 
> Signed-off-by: Brian Masney <masneyb@...tation.org>
Whilst I'm not against it by an means, runtime PM is hardly a requirement
for moving out of staging! Good stuff though so I'm not going to turn it
down ;)

I'm not 100% sure about the one comment I made at the end.
It's a very unlikely to occur condition anyway, but if you want to follow up
with a patch on that then feel free.

Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

thanks,

Jonathan
> ---
>  drivers/staging/iio/light/isl29028.c | 118 ++++++++++++++++++++++++++++++++---
>  1 file changed, 110 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/iio/light/isl29028.c b/drivers/staging/iio/light/isl29028.c
> index 598a5a5..a3264f7 100644
> --- a/drivers/staging/iio/light/isl29028.c
> +++ b/drivers/staging/iio/light/isl29028.c
> @@ -26,6 +26,7 @@
>  #include <linux/regmap.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/pm_runtime.h>
>  
>  #define ISL29028_CONV_TIME_MS			100
>  
> @@ -60,6 +61,8 @@
>  
>  #define ISL29028_NUM_REGS			(ISL29028_REG_TEST2_MODE + 1)
>  
> +#define ISL29028_POWER_OFF_DELAY_MS		2000
> +
>  enum isl29028_als_ir_mode {
>  	ISL29028_MODE_NONE = 0,
>  	ISL29028_MODE_ALS,
> @@ -297,6 +300,23 @@ static int isl29028_ir_get(struct isl29028_chip *chip, int *ir_data)
>  	return isl29028_read_als_ir(chip, ir_data);
>  }
>  
> +static int isl29028_set_pm_runtime_busy(struct isl29028_chip *chip, bool on)
> +{
> +	struct device *dev = regmap_get_device(chip->regmap);
> +	int ret;
> +
> +	if (on) {
> +		ret = pm_runtime_get_sync(dev);
> +		if (ret < 0)
> +			pm_runtime_put_noidle(dev);
> +	} else {
> +		pm_runtime_mark_last_busy(dev);
> +		ret = pm_runtime_put_autosuspend(dev);
> +	}
> +
> +	return ret;
> +}
> +
>  /* Channel IO */
>  static int isl29028_write_raw(struct iio_dev *indio_dev,
>  			      struct iio_chan_spec const *chan,
> @@ -304,9 +324,15 @@ static int isl29028_write_raw(struct iio_dev *indio_dev,
>  {
>  	struct isl29028_chip *chip = iio_priv(indio_dev);
>  	struct device *dev = regmap_get_device(chip->regmap);
> -	int ret = -EINVAL;
> +	int ret;
> +
> +	ret = isl29028_set_pm_runtime_busy(chip, true);
> +	if (ret < 0)
> +		return ret;
>  
>  	mutex_lock(&chip->lock);
> +
> +	ret = -EINVAL;
>  	switch (chan->type) {
>  	case IIO_PROXIMITY:
>  		if (mask != IIO_CHAN_INFO_SAMP_FREQ) {
> @@ -350,6 +376,13 @@ static int isl29028_write_raw(struct iio_dev *indio_dev,
>  
>  	mutex_unlock(&chip->lock);
>  
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = isl29028_set_pm_runtime_busy(chip, false);
> +	if (ret < 0)
> +		return ret;
> +
>  	return ret;
>  }
>  
> @@ -359,9 +392,15 @@ static int isl29028_read_raw(struct iio_dev *indio_dev,
>  {
>  	struct isl29028_chip *chip = iio_priv(indio_dev);
>  	struct device *dev = regmap_get_device(chip->regmap);
> -	int ret = -EINVAL;
> +	int ret, pm_ret;
> +
> +	ret = isl29028_set_pm_runtime_busy(chip, true);
> +	if (ret < 0)
> +		return ret;
>  
>  	mutex_lock(&chip->lock);
> +
> +	ret = -EINVAL;
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
>  	case IIO_CHAN_INFO_PROCESSED:
> @@ -405,6 +444,18 @@ static int isl29028_read_raw(struct iio_dev *indio_dev,
>  
>  	mutex_unlock(&chip->lock);
>  
> +	if (ret < 0)
> +		return ret;
> +
> +	/**
> +	 * Preserve the ret variable if the call to
> +	 * isl29028_set_pm_runtime_busy() is successful so the reading
> +	 * (if applicable) is returned to user space.
> +	 */
> +	pm_ret = isl29028_set_pm_runtime_busy(chip, false);
> +	if (pm_ret < 0)
> +		return pm_ret;
> +
>  	return ret;
>  }
>  
> @@ -445,17 +496,18 @@ static const struct iio_info isl29028_info = {
>  	.write_raw = isl29028_write_raw,
>  };
>  
> -static int isl29028_chip_init_and_power_on(struct isl29028_chip *chip)
> +static int isl29028_clear_configure_reg(struct isl29028_chip *chip)
>  {
>  	struct device *dev = regmap_get_device(chip->regmap);
>  	int ret;
>  
>  	ret = regmap_write(chip->regmap, ISL29028_REG_CONFIGURE, 0x0);
> -	if (ret < 0) {
> +	if (ret < 0)
>  		dev_err(dev, "%s(): Error %d clearing the CONFIGURE register\n",
>  			__func__, ret);
> -		return ret;
> -	}
> +
> +	chip->als_ir_mode = ISL29028_MODE_NONE;
> +	chip->enable_prox = false;
>  
>  	return ret;
>  }
> @@ -509,7 +561,6 @@ static int isl29028_probe(struct i2c_client *client,
>  	chip->enable_prox  = false;
>  	chip->prox_sampling = 20;
>  	chip->lux_scale = 2000;
> -	chip->als_ir_mode = ISL29028_MODE_NONE;
>  
>  	ret = regmap_write(chip->regmap, ISL29028_REG_TEST1_MODE, 0x0);
>  	if (ret < 0) {
> @@ -527,7 +578,7 @@ static int isl29028_probe(struct i2c_client *client,
>  		return ret;
>  	}
>  
> -	ret = isl29028_chip_init_and_power_on(chip);
> +	ret = isl29028_clear_configure_reg(chip);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -538,6 +589,11 @@ static int isl29028_probe(struct i2c_client *client,
>  	indio_dev->dev.parent = &client->dev;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  
> +	pm_runtime_enable(&client->dev);
> +	pm_runtime_set_autosuspend_delay(&client->dev,
> +					 ISL29028_POWER_OFF_DELAY_MS);
> +	pm_runtime_use_autosuspend(&client->dev);
> +
>  	ret = devm_iio_device_register(indio_dev->dev.parent, indio_dev);
>  	if (ret < 0) {
>  		dev_err(&client->dev,
> @@ -549,6 +605,50 @@ static int isl29028_probe(struct i2c_client *client,
>  	return 0;
>  }
>  
> +static int isl29028_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct isl29028_chip *chip = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +	pm_runtime_put_noidle(&client->dev);
> +
> +	return isl29028_clear_configure_reg(chip);
> +}
> +
> +static int __maybe_unused isl29028_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct isl29028_chip *chip = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&chip->lock);
> +
> +	ret = isl29028_clear_configure_reg(chip);
I'm stretching a bit, but there might be a race here.
If we get a suspend and resume in under the time it takes for
the auto suspend to conclude it is good to suspend, it might think
the device is still ready to go when it isn't.
> +
> +	mutex_unlock(&chip->lock);
> +
> +	return ret;
> +}
> +
> +static int __maybe_unused isl29028_resume(struct device *dev)
> +{
> +	/**
> +	 * The specific component (ALS/IR or proximity) will enable itself as
> +	 * needed the next time that the user requests a reading. This is done
> +	 * above in isl29028_set_als_ir_mode() and isl29028_enable_proximity().
> +	 */
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops isl29028_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(isl29028_suspend, isl29028_resume)
> +	SET_RUNTIME_PM_OPS(isl29028_suspend, isl29028_resume, NULL)
> +};
> +
>  static const struct i2c_device_id isl29028_id[] = {
>  	{"isl29028", 0},
>  	{}
> @@ -565,9 +665,11 @@ MODULE_DEVICE_TABLE(of, isl29028_of_match);
>  static struct i2c_driver isl29028_driver = {
>  	.driver  = {
>  		.name = "isl29028",
> +		.pm = &isl29028_pm_ops,
>  		.of_match_table = isl29028_of_match,
>  	},
>  	.probe	 = isl29028_probe,
> +	.remove  = isl29028_remove,
>  	.id_table = isl29028_id,
>  };
>  
> 

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