Re: [PATCH 4/7] PM / Domains: Rework system suspend callback routines

Rafael J. Wysocki
2012-02-17T20:57:14Z

On Friday, February 17, 2012, Pavel Machek wrote:
> On Mon 2011-11-07 01:08:11, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > The current generic PM domains code attempts to use the generic
> > system suspend operations along with the domains' device stop/start
> > routines, which requires device drivers to assume that their
> > system suspend/resume (and hibernation/restore) callbacks will always
> > be used with generic PM domains. However, in theory, the same
> > hardware may be used in devices that don't belong to any PM domain,
> > in which case it would be necessary to add "fake" PM domains to
> > satisfy the above assumption. Also, the domain the hardware belongs
> > to may not be handled with the help of the generic code.
> >
> > To allow device drivers that may be used along with the generic PM
> > domains code of more flexibility, add new device callbacks, .freeze(),
> > .freeze_late(), .thaw_early() and .thaw(), that can be supplied by
> > the drivers in addition to their "standard" system suspend and
> > hibernation callbacks. These new callbacks, if defined, will be used
> > by the generic PM domains code for the handling of system suspend and
> > hibernation instead of the "standard" ones. This will allow drivers
> > to be designed to work with generic PM domains as well as without
> > them.
>
> Should this go to Documentation/ somewhere? May concern is that we
> have way too many callbacks these days. Why is fake PM domain such a
> bad thing?

I'm not sure what you mean, really. This particular patch only affects
the generic PM domains framework, which only has a few users now.

Thanks,
Rafael