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SubjectRe: [PATCH v3 1/2] hwmon: (lm90) Add power control
On 09/09/2013 09:36 PM, Guenter Roeck wrote:
> On 09/09/2013 08:22 PM, Wei Ni wrote:
>> On 09/09/2013 11:50 PM, Guenter Roeck wrote:
>>> On Mon, Sep 09, 2013 at 02:50:22PM +0100, Mark Brown wrote:
>>>> On Mon, Sep 09, 2013 at 04:34:43AM -0700, Guenter Roeck wrote:
>>>>> On 09/09/2013 04:12 AM, Mark Brown wrote:
>>>>>> On Mon, Sep 09, 2013 at 06:29:11PM +0800, Wei Ni wrote:
>>>>
>>>>>> This doesn't look good, it is going to ignore actual errors - I
>>>>>> *really*
>>>>>> doubt that vcc is optional, it looks like it's the main power
>>>>>> supply for
>>>>>> the device. You should use normal regulator_get(), _optional() is
>>>>>> for
>>>>>> supplies which could physically not be provided in a system (eg,
>>>>>> if the
>>>>>> device can generate them internally if required).
>>>>
>>>>> Then he'll have to make sure that all devicetree files in the system
>>>>> contain references to this regulator.
>>>>
>>>> Or get the patches applied on top of the code that'll be going in this
>>>> cycle implementing get_optional() properly - when that's done the
>>>> default will be to provide a dummy supply for regulator_get(). If you
>>>> ack the patch I'd be happy to carry it.
>>>>
>>> Jean will have to ack it.
>>>
>> I think it's better to use get_optional(), and ignore the errors except
>> -EPROBE_DEFER. Because many platform may always power on this device,
>> and will not provide regulator for it, so if we get errors from
>> regulator subsystem and return it directly, then the probe() can't be
>> implemented, this driver can't work properly, even though it can work
>> without regulator support.
>> Mark, do you mean you have patches for regulator_get_optional() and
>> regulator_get()?
>>
>
> My understanding is that by adding regulator support you essentially
> committed to adding regulators (if necessary dummy ones) for this driver
> to all those platforms. This is quite similar to other drivers in the
> same situation. Once you start along that route, you'll have to go it
> all the way.

By using regulator_get_optional(), the regulator should be optional,
hence you only have to add it to platforms that need it.



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