Re: suspend/resume support for driver requires an external firmware

[Pavel Machek <pavel-AlSwsSmVLrQ@public.gmane.org>]

Hi!

> > I make the ipw2100 driver (http://ipw2100.sf.net) support suspend/resume
> > with below patch.
> > http://cache.gmane.org//gmane/linux/drivers/ipw2100/devel/2129-001.bin
> > 
> > Current state is the patch makes ipw2100 suspend/resume work in the
> > expense
> > of addtional ~200k kernel runtime memory. So I'd rather look on it as a
> > workaround instead of a finial solution.
> > 
> > The problem is ipw2100 requires an external on-disk firmware support. When
> > the device is put to D3 state, firmware needs to be unloaded. And the
> > firmware should be loaded again after the device is put to D0 state. But
> > currently there is no suspend/resume order(dependency) for the online
> > devices list in the kernel (dpm_active). So the ide disk might still be in
> > the suspend state when ipw2100->resume is called. This causes a deadlock.
> > 
> > 
> > I propose 2 choices to fix the problem.
> > 
> > Choice 1. In 2.5 kernel, there used to be a ->save_state method in the
> > device PM interface. From the "not yet updated" document
> > 
> > Choice 2. Add a notifier call chain for swsusp before prepare_suspend.
> > Each
> > driver requires the notification(i.e. ipw2100) registers its own callback.
> > For people who think device PM ->save_state is an overkill since 99%
> > devices
> > don't require firmwares (really today, who knows the future?), this can be
> > considered as another (better) solution.
> > 
> > 
> > Choice 3? or I missed something here?
> > 
> 
> What about splitting resume in 2 parts - the ->resume method
> would just schedule_work() real resume for the card out of
> line where it can safely wait for drive to be available without
> blocking other devices from resuming. This way you do not need
> to pre-load firmware on suspend.

That way, userspace could see wifi card in half-suspended state. Not
good.

								Pavel
-- 
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!


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