Re: [PATCH 0/3] PM / core: Invent a WAKEUP_POWERED driver flag

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On Thu, Nov 9, 2017 at 3:41 PM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> Hi Ulf,
>
> On Thu, Nov 9, 2017 at 3:28 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>> [...]
>>
>>>>> The Ethernet driver can still call device_set_wakeup_enable(... , false)
>>>>> to control this.  If WoL is disabled by the user (or deemed not usable, see
>>>>> below), it already does so.
>>>>
>>>> I don't think that API is intended to be used like that and I wonder
>>>> if it even works as expected.
>>>>
>>>> Quoting the doc:
>>>> "If device wakeup mechanisms are enabled or disabled directly by
>>>> drivers, they also should use :c:func:`device_may_wakeup()` to decide what to do
>>>> during a system sleep transition.  Device drivers, however, are not expected to
>>>> call :c:func:`device_set_wakeup_enable()` directly in any case."
>>>>
>>>> Rafael, can you comment on this?
>>>
>>> There are ca. 100 callers in drivers.
>>
>> Yeah, but those doesn't normally use it to toggle the setting, but
>> instead only to set a default value during ->probe() or whatever
>> initialization code that runs.
>>
>> I think that makes a big difference, doesn't it?
>
> The few Ethernet drivers I looked at change the state in their
> ethtool_ops.set_wol() callback, not during probe.
> This is to be configured from userspace using ethtool.

Which is the case I was talking about.

Since changing the WoL setting via ethtool is expected to cause the
sysfs knob to reflect its status, using device_set_wakeup_enable() in
there is not actually confusing.

The same applies to setting the default from ->probe().

It will be confusing in all of the other cases, though.

Thanks,
Rafael



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