[PATCH 1/2] hwmon: (lm90) Add power control
Guenter Roeck
linux at roeck-us.net
Wed Aug 7 03:50:04 EDT 2013
On 08/07/2013 12:32 AM, Wei Ni wrote:
> 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 <wni at nvidia.com>
>>> ---
>>> 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.
>
Then why does no other caller of regulator_enable() need this ?
I don't think lm90 is so much different to other users of regulator
functionality.
Besides that, your delay is unconditional, even for static regulators
which are always on. Other callers of regulator_enable() don't need
all that complexity, which I take as sign that it is not needed here either.
Guenter
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