Re: [linux-pm] subtle pm_runtime_put_sync race and sdio functions

[Ohad Ben-Cohen <ohad@wizery.com>]

On Sat, Dec 18, 2010 at 6:40 PM, Johannes Berg
<johannes@sipsolutions.net> wrote:
> On Sat, 2010-12-18 at 18:00 +0200, Ohad Ben-Cohen wrote:
>
>> > That's where the problem is.  If there's a difference, from the driver's
>> > point of view, between suspend and some other operation, there should be a
>> > way to tell the driver what case it actually is dealing with.
>>
>> Yes, the problem will be solved if the driver would bypass the runtime
>> PM framework on system suspend. mac80211 obviously has this
>> information, and technically it's very easy to let the driver know
>> about it.
>>
>> But the difference between suspend and normal operation is really
>> artificial: in both cases mac80211 just asks the driver to power its
>> device down, and the end result is exactly the same (a GPIO line of
>> the device is de-asserted in our case). The difference between these
>> two scenarios
>> exist only because runtime PM is effectively disabled during system
>> suspend, and therefore the driver has to look for an alternative way
>> to power down the device.
>
> Sounds to me like the difference isn't really in the driver, but the
> core PM subsystem. Why does it care when powering off a device whether
> it's during suspend, or during runtime?

Agree.

If we can add a dev_pm_info bit, that would allow using runtime PM API
during suspend/resume transitions, the driver will not have to care.

Rafael what do you think ? Is that totally unacceptable ?

Thanks,
Ohad.