Re: [PATCH v5 1/1] iio: pulsedlight-lidar-lite: add runtime PM

[Jonathan Cameron <jic23@kernel.org>]

On 16/11/15 01:20, Matt Ranostay wrote:
> Add runtime PM support for the lidar-lite module to enable low power
> mode when last device requested reading is over a second.
> 
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
In principal fine. One small comment inline.
It's not critical in any way so 
applied to the togreg branch of iio.git - initially pushed out
as testing for the autobuilders to play with it.

Also, a tiny process point. It's rarely worth bothering with a cover
letter for a single patch - just put extra info below the --- in the patch
itself.

Jonathan
> ---
>  drivers/iio/proximity/pulsedlight-lidar-lite-v2.c | 56 ++++++++++++++++++++++-
>  1 file changed, 55 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> index 961f9f99..be8ccef 100644
> --- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> +++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> @@ -13,7 +13,7 @@
>   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>   * GNU General Public License for more details.
>   *
> - * TODO: runtime pm, interrupt mode, and signal strength reporting
> + * TODO: interrupt mode, and signal strength reporting
>   */
>  
>  #include <linux/err.h>
> @@ -21,6 +21,7 @@
>  #include <linux/i2c.h>
>  #include <linux/delay.h>
>  #include <linux/module.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
>  #include <linux/iio/buffer.h>
> @@ -37,6 +38,7 @@
>  
>  #define LIDAR_REG_DATA_HBYTE	0x0f
>  #define LIDAR_REG_DATA_LBYTE	0x10
> +#define LIDAR_REG_PWR_CONTROL	0x65
>  
>  #define LIDAR_DRV_NAME "lidar"
>  
> @@ -90,6 +92,12 @@ static inline int lidar_write_control(struct lidar_data *data, int val)
>  	return i2c_smbus_write_byte_data(data->client, LIDAR_REG_CONTROL, val);
>  }
>  
> +static inline int lidar_write_power(struct lidar_data *data, int val)
> +{
> +	return i2c_smbus_write_byte_data(data->client,
> +					 LIDAR_REG_PWR_CONTROL, val);
> +}
This wrapper doesn't do all that much.  It might have been worth
a wrapper if you took a boolean in instead of val.  As it stands
the user still needs to know what magic value to write to the register.
As such I'd drop the wrapper and call the i2c_smbus_write_byte_data
directly where needed.

> +
>  static int lidar_read_measurement(struct lidar_data *data, u16 *reg)
>  {
>  	int ret;
> @@ -116,6 +124,8 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
>  	int tries = 10;
>  	int ret;
>  
> +	pm_runtime_get_sync(&client->dev);
> +
>  	/* start sample */
>  	ret = lidar_write_control(data, LIDAR_REG_CONTROL_ACQUIRE);
>  	if (ret < 0) {
> @@ -144,6 +154,8 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
>  		}
>  		ret = -EIO;
>  	}
> +	pm_runtime_mark_last_busy(&client->dev);
> +	pm_runtime_put_autosuspend(&client->dev);
>  
>  	return ret;
>  }
> @@ -243,6 +255,17 @@ static int lidar_probe(struct i2c_client *client,
>  	if (ret)
>  		goto error_unreg_buffer;
>  
> +	pm_runtime_set_autosuspend_delay(&client->dev, 1000);
> +	pm_runtime_use_autosuspend(&client->dev);
> +
> +	ret = pm_runtime_set_active(&client->dev);
> +	if (ret)
> +		goto error_unreg_buffer;
> +	pm_runtime_enable(&client->dev);
> +
> +	pm_runtime_mark_last_busy(&client->dev);
> +	pm_runtime_idle(&client->dev);
> +
>  	return 0;
>  
>  error_unreg_buffer:
> @@ -258,6 +281,9 @@ static int lidar_remove(struct i2c_client *client)
>  	iio_device_unregister(indio_dev);
>  	iio_triggered_buffer_cleanup(indio_dev);
>  
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +
>  	return 0;
>  }
>  
> @@ -273,10 +299,38 @@ static const struct of_device_id lidar_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, lidar_dt_ids);
>  
> +#ifdef CONFIG_PM
> +static int lidar_pm_runtime_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct lidar_data *data = iio_priv(indio_dev);
> +
> +	return lidar_write_power(data, 0x0f);
> +}
> +
> +static int lidar_pm_runtime_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct lidar_data *data = iio_priv(indio_dev);
> +	int ret = lidar_write_power(data, 0);
> +
> +	/* regulator and FPGA needs settling time */
> +	usleep_range(15000, 20000);
> +
> +	return ret;
> +}
> +#endif
> +
> +static const struct dev_pm_ops lidar_pm_ops = {
> +	SET_RUNTIME_PM_OPS(lidar_pm_runtime_suspend,
> +			   lidar_pm_runtime_resume, NULL)
> +};
> +
>  static struct i2c_driver lidar_driver = {
>  	.driver = {
>  		.name	= LIDAR_DRV_NAME,
>  		.of_match_table	= of_match_ptr(lidar_dt_ids),
> +		.pm	= &lidar_pm_ops,
>  	},
>  	.probe		= lidar_probe,
>  	.remove		= lidar_remove,
>