[PATCH] powerpc/85xx: don't init the mpic ipi for the SoC which has doorbell support

[Scott Wood]

On Fri, 2013-11-08 at 09:54 +0800, Kevin Hao wrote:
> On Thu, Nov 07, 2013 at 11:34:51AM -0600, Scott Wood wrote:
> > On Thu, 2013-11-07 at 15:17 +0800, Kevin Hao wrote:
> > > It makes no sense to initialize the mpic ipi for the SoC which has
> > > doorbell support. So set the smp_85xx_ops.probe to NULL for this
> > > case. Since the smp_85xx_ops.probe is also used in function
> > > smp_85xx_setup_cpu() to check if we need to invoke
> > > mpic_setup_this_cpu(), we introduce a new setup_cpu function
> > > smp_85xx_basic_setup() to remove this dependency.
> > 
> > Is there any harm caused by setting up the IPIs?
> 
> No real harm. Just make no sense to do so and it does cause confusion
> when you cat /proc/interrupts and get something like this:
>   507:          0          0   OpenPIC   2043 Edge      ipi call function
>   508:          0          0   OpenPIC   2044 Edge      ipi reschedule
>   509:          0          0   OpenPIC   2045 Edge      ipi call function single
>   DBL:       7053      10137   Doorbell interrupts
> 
> > 
> > What about other MPIC setup, such as setting the current task priority
> > register?
> 
> This is done by the invoking of function mpic_setup_this_cpu() in
> smp_85xx_setup_cpu().

OK...  Why are you splitting out smp_85xx_basic_setup()?  Where do you
call it other than from smp_85xx_setup_cpu()?  Couldn't you have just
removed the conditional without splitting up the function?  The change
log says it's "to check if we need to invoke mpic_setup_this_cpu()"
which doesn't make sense since we always want to call
mpic_setup_this_cpu() if we have an MPIC.

-Scott