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

[Kim Phillips <kim.phillips@freescale.com>]

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. :)

Kim