Re: [PATCH v4] pm_ops: add system quiesce/activate hooks

[Pavel Machek <pavel@ucw.cz>]

On Fri 2007-04-13 23:45:48, Johannes Berg wrote:
> On Fri, 2007-04-13 at 23:33 +0200, Pavel Machek wrote:
> 
> > Still, swsusp shuts down the devices:
> > 
> >         if ((error = arch_prepare_suspend()))
> >                 return error;
> > 
> >         local_irq_disable();
> >         /* At this point, device_suspend() has been called, but *not*
> >          * device_power_down(). We *must* device_power_down() now.
> >          * Otherwise, drivers for some devices (e.g. interrupt
> > controllers)
> >          * become desynchronized with the actual state of the hardware
> >          * at resume time, and evil weirdness ensues.
> >          */
> >         if ((error = device_power_down(PMSG_FREEZE))) {
> >                 printk(KERN_ERR "Some devices failed to power down, aborting suspend\n");
> >                 goto Enable_irqs;
> >         }
> > 
> > This local_irq_disable() is very similar to the one you are doing in
> > suspend-to-RAM. According to your description, it needs to play with
> > the decrementor, too. But I'd really prefer not to have pm_ops call
> > here -- exactly because swsusp has nothing to do with pm_ops in
> > shutdown mode.
> 
> Right. But we don't actually care because we just power down, we don't
> have to put the CPU into a proper state.

Look again, this sequence is before taking system snapshot, and then
we have to recover and save the snapshot, too.

									Pavel
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