[linux-pm] [PATCH 01/13] PM: Add wake lock api.

[Nigel Cunningham]

On Thu, 2009-02-12 at 18:21 -0800, Arve Hjønnevåg wrote:
> On Thu, Feb 12, 2009 at 5:10 PM, Matthew Garrett <mjg59 at srcf.ucam.org> wrote:
> > I dislike the kernel-side use of wakelocks. They're basically equivalent
> > to a device returning -EBUSY during the suspend phase, which is
> > something that can be done without any kernel modifications.
> 
> I don't get why people object to wakelocks supporting timeouts, but
> think drivers returning -EBUSY to abort suspend is ok. If suspend
> fails, the higher level code has to periodically retry until it can
> succeed. This means that the device is awake for longer than it need
> to, and you are repeatedly wasting time freezing all tasks and
> suspending a set of drivers before you get to the driver that is
> preventing suspend.

I for one don't think drivers returning -EBUSY is okay. Once a user asks
for suspend to ram or hibernation, nothing but improper configuration
(in the hibernation case) should stop them getting it. Even if they ask
to suspend to ram in the middle of writing a cd, they should get the
suspend to ram. But, of course, I'm just one voice.

Regards,

Nigel