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

[Guenter Roeck]

On 08/07/2013 12:27 AM, 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@xxxxxxxxxx>
> > ---
> >   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?

Good question. Browsing through other regulator_enable calls,
I don't see a similar delay anywhere else, so one should assume
that this is not necessary.

Guenter

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