Re: [PATCH 2/2] enable generic rtc hook for the MPC8349 mITX

[Tom Rini <trini@kernel.crashing.org>]

On Wed, Sep 27, 2006 at 11:43:04PM -0500, Kim Phillips wrote:
> On Wed, 27 Sep 2006 08:58:53 -0700
> Tom Rini <trini@kernel.crashing.org> wrote:
> 
> > On Tue, Sep 26, 2006 at 11:34:43PM -0500, Kumar Gala wrote:
> > > On Sep 26, 2006, at 5:46 PM, Kim Phillips wrote:
> > [snip]
> > > > diff --git a/arch/powerpc/platforms/83xx/mpc834x_itx.c b/arch/ 
> > > > powerpc/platforms/83xx/mpc834x_itx.c
> > > > index 969fbb6..8c676d7 100644
> > > > --- a/arch/powerpc/platforms/83xx/mpc834x_itx.c
> > > > +++ b/arch/powerpc/platforms/83xx/mpc834x_itx.c
> > > > @@ -109,6 +109,10 @@ static int __init mpc834x_itx_probe(void
> > > >  	return 1;
> > > >  }
> > > >
> > > > +#ifdef CONFIG_RTC_CLASS
> > > > +late_initcall(rtc_class_hookup);
> > > > +#endif
> > > 
> > > Any reason we can't just do this in setup_arch?
> > 
> > I think because of rtc-over-i2c and similar where we need the whole rest
> > of the system 'up' before we can try and use the RTC (which might not be
> > the case for this specific board, but for consistency it looks like a
> > good thing to always do it like this).
> > 
> this is indeed the case, as with the static assignment of the ppc_md rtc_time functions in define_machine.  In the early assignment case, the kernel oopses early in rtc_class_open().
> 
> During testing I noticed hwclock get/set operations worked even without hooking up with the ppc_md rtc_time functions.  Turns out this rtc_class provides access to the RTC to the whole kernel and userspace:
> 
> http://lkml.org/lkml/2005/12/20/220
> 
> so, both of these patches are really unnecessary, unless there's a genuine consumer in arch/powerpc that I can't find (I'm assuming get_boot_time() isn't one of them since it gets called way too early in the rtc-over-i2c based platform case).
> 
> So we should just configure RTC_CLASS and the specific chip and we're done. :)

Does this mean we can then rip out some existing code, so long as
there's associated cleanup / rtc class support additions?

-- 
Tom Rini