Subject: [PATCH 1/2] hwmon: (lm90) Add power control

From: [email-masked] (Wei Ni)
Date: Wed, 7 Aug 2013 15:32:33 +0800

On 08/07/2013 03:27 PM, Alexander Shiyan wrote:
>> The device lm90 can be controlled by the vdd rail.
>> Adding the power control support to power on/off the vdd rail.
>> And make sure that power is enabled before accessing the device.
>>
>> Signed-off-by: Wei Ni <[email-masked]>
>> ---
>>  drivers/hwmon/lm90.c |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++
> [...]
>> +	if (!data->lm90_reg) {
>> +		data->lm90_reg = regulator_get(&client->dev, "vdd");
>> +		if (IS_ERR_OR_NULL(data->lm90_reg)) {
>> +			if (PTR_ERR(data->lm90_reg) == -ENODEV)
>> +				dev_info(&client->dev,
>> +					 "No regulator found for vdd. Assuming vdd is always powered.");
>> +			else
>> +				dev_warn(&client->dev,
>> +					 "Error [%ld] in getting the regulator handle for vdd.\n",
>> +					 PTR_ERR(data->lm90_reg));
>> +			data->lm90_reg = NULL;
>> +			mutex_unlock(&data->update_lock);
>> +			return -ENODEV;
>> +		}
>> +	}
>> +	if (is_enable) {
>> +		ret = regulator_enable(data->lm90_reg);
>> +		msleep(POWER_ON_DELAY);
> 
> Can this delay be handled directly from regulator?

I think it should be handled in the device driver.
Because there have different delay time to wait devices stable.

> [...]
> ---