Re: [PATCH] fix tulip suspend/resume

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2005-06-07 at 15:51 +1000, Nigel Cunningham wrote:
> Hi.
> 
> On Tue, 2005-06-07 at 15:03, Adam Belay wrote:
> > I'd tend to agree with Pat then.  The original pm_ops seem to be
> > designed around ACPI and after looking at the spec I don't think they're
> > correct. (e.g. it looks like _PTS and _GTS should be run after
> > device_suspend() instead of before, so *prepare may not be needed).  In
> > short, this tends to be tricky.  It's probably best to have platforms
> > handle it on their own with kernel/power as a library.
> 
> Hmm....
> 
> - We need a lot of arch dependent hooks so the right things are done at
> the right time
> - We need a lot of arch independent code run between the arch dependent
> code so that the right things are done at the right time.
> 
> Therefore it doesn't matter whether the centre of the universe is arch
> dependent or independent - either way we have to have hooks to get the
> other stuff done.

Except that one direction is hooks, the other is normal function calls,
that is, one is up layer with hook to low level the other is up layer
calling library to low level, I prefer the later.
 
> Swsusp takes a minimalist design, so it doesn't look like much to worry
> about if some of that code gets duplicated in arch specific places (taht
> said, I'm not sure what whoever-it-was was thinking of duplicating).
> Suspend2 takes a feature complete/user friendly/etc design and therefore
> has a lot more arch independent code. We definitely want to minimise
> duplication of code there.

There may not be much differences, but I'll have to look at your code to
see.

> So I'd suggest leaving the arch independent code in the drivers seat,
> but simultaneously replacing/redesigning pm_ops & swsusp so that all the
> ops that are or might be needed are there and called at the appropriate
> time.