Re: [PATCH v2] HID: i2c-hid: add runtime PM support

[Jiri Kosina]

On Wed, 29 Jan 2014, Mika Westerberg wrote:

> This patch adds runtime PM support for the HID over I2C driver. When the
> i2c-hid device is first opened we power it on and on the last close we
> power it off. This is actually what the driver is already doing but in
> addition it allows subsystems, like ACPI power domain to power off the
> device during runtime PM suspend, which should save even more power.
> 
> The implementation is not the most power efficient because it needs some
> interaction from the userspace (e.g close the device node whenever we are
> no more interested in getting events), nevertheless it allows us to save
> some power and works with devices that are not wake capable.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> ---
> v2:
>   - Update changelog to mention that ACPI power domain for example can
>     power off the device on suspend.
>   - Make i2c_hid_power to just call RPM get/put

Applied, thanks Mika, thanks Benjamin.

> 
>  drivers/hid/i2c-hid/i2c-hid.c | 68 ++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 57 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index d1f81f52481a..923ff818a1bf 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -25,6 +25,7 @@
>  #include <linux/delay.h>
>  #include <linux/slab.h>
>  #include <linux/pm.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/device.h>
>  #include <linux/wait.h>
>  #include <linux/err.h>
> @@ -454,10 +455,18 @@ static void i2c_hid_init_reports(struct hid_device *hid)
>  		return;
>  	}
>  
> +	/*
> +	 * The device must be powered on while we fetch initial reports
> +	 * from it.
> +	 */
> +	pm_runtime_get_sync(&client->dev);
> +
>  	list_for_each_entry(report,
>  		&hid->report_enum[HID_FEATURE_REPORT].report_list, list)
>  		i2c_hid_init_report(report, inbuf, ihid->bufsize);
>  
> +	pm_runtime_put(&client->dev);
> +
>  	kfree(inbuf);
>  }
>  
> @@ -703,8 +712,8 @@ static int i2c_hid_open(struct hid_device *hid)
>  
>  	mutex_lock(&i2c_hid_open_mut);
>  	if (!hid->open++) {
> -		ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
> -		if (ret) {
> +		ret = pm_runtime_get_sync(&client->dev);
> +		if (ret < 0) {
>  			hid->open--;
>  			goto done;
>  		}
> @@ -712,7 +721,7 @@ static int i2c_hid_open(struct hid_device *hid)
>  	}
>  done:
>  	mutex_unlock(&i2c_hid_open_mut);
> -	return ret;
> +	return ret < 0 ? ret : 0;
>  }
>  
>  static void i2c_hid_close(struct hid_device *hid)
> @@ -729,7 +738,7 @@ static void i2c_hid_close(struct hid_device *hid)
>  		clear_bit(I2C_HID_STARTED, &ihid->flags);
>  
>  		/* Save some power */
> -		i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
> +		pm_runtime_put(&client->dev);
>  	}
>  	mutex_unlock(&i2c_hid_open_mut);
>  }
> @@ -738,19 +747,18 @@ static int i2c_hid_power(struct hid_device *hid, int lvl)
>  {
>  	struct i2c_client *client = hid->driver_data;
>  	struct i2c_hid *ihid = i2c_get_clientdata(client);
> -	int ret = 0;
>  
>  	i2c_hid_dbg(ihid, "%s lvl:%d\n", __func__, lvl);
>  
>  	switch (lvl) {
>  	case PM_HINT_FULLON:
> -		ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
> +		pm_runtime_get_sync(&client->dev);
>  		break;
>  	case PM_HINT_NORMAL:
> -		ret = i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
> +		pm_runtime_put(&client->dev);
>  		break;
>  	}
> -	return ret;
> +	return 0;
>  }
>  
>  static struct hid_ll_driver i2c_hid_ll_driver = {
> @@ -973,13 +981,17 @@ static int i2c_hid_probe(struct i2c_client *client,
>  	if (ret < 0)
>  		goto err;
>  
> +	pm_runtime_get_noresume(&client->dev);
> +	pm_runtime_set_active(&client->dev);
> +	pm_runtime_enable(&client->dev);
> +
>  	ret = i2c_hid_fetch_hid_descriptor(ihid);
>  	if (ret < 0)
> -		goto err;
> +		goto err_pm;
>  
>  	ret = i2c_hid_init_irq(client);
>  	if (ret < 0)
> -		goto err;
> +		goto err_pm;
>  
>  	hid = hid_allocate_device();
>  	if (IS_ERR(hid)) {
> @@ -1010,6 +1022,7 @@ static int i2c_hid_probe(struct i2c_client *client,
>  		goto err_mem_free;
>  	}
>  
> +	pm_runtime_put(&client->dev);
>  	return 0;
>  
>  err_mem_free:
> @@ -1018,6 +1031,10 @@ err_mem_free:
>  err_irq:
>  	free_irq(client->irq, ihid);
>  
> +err_pm:
> +	pm_runtime_put_noidle(&client->dev);
> +	pm_runtime_disable(&client->dev);
> +
>  err:
>  	i2c_hid_free_buffers(ihid);
>  	kfree(ihid);
> @@ -1029,6 +1046,11 @@ static int i2c_hid_remove(struct i2c_client *client)
>  	struct i2c_hid *ihid = i2c_get_clientdata(client);
>  	struct hid_device *hid;
>  
> +	pm_runtime_get_sync(&client->dev);
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +	pm_runtime_put_noidle(&client->dev);
> +
>  	hid = ihid->hid;
>  	hid_destroy_device(hid);
>  
> @@ -1074,7 +1096,31 @@ static int i2c_hid_resume(struct device *dev)
>  }
>  #endif
>  
> -static SIMPLE_DEV_PM_OPS(i2c_hid_pm, i2c_hid_suspend, i2c_hid_resume);
> +#ifdef CONFIG_PM_RUNTIME
> +static int i2c_hid_runtime_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
> +	disable_irq(client->irq);
> +	return 0;
> +}
> +
> +static int i2c_hid_runtime_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	enable_irq(client->irq);
> +	i2c_hid_set_power(client, I2C_HID_PWR_ON);
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops i2c_hid_pm = {
> +	SET_SYSTEM_SLEEP_PM_OPS(i2c_hid_suspend, i2c_hid_resume)
> +	SET_RUNTIME_PM_OPS(i2c_hid_runtime_suspend, i2c_hid_runtime_resume,
> +			   NULL)
> +};
>  
>  static const struct i2c_device_id i2c_hid_id_table[] = {
>  	{ "hid", 0 },
> -- 
> 1.8.5.2
> 

-- 
Jiri Kosina
SUSE Labs
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