Re: [PATCH] powerpc/pasemi,cbe: Do not process decremeter or external wakeup from powersave

[Nicholas Piggin <npiggin@gmail.com>]

On Fri, 17 Mar 2017 17:12:11 +1100
Michael Ellerman <mpe@ellerman.id.au> wrote:

> Michael Ellerman <mpe@ellerman.id.au> writes:
> 
> > Nicholas Piggin <npiggin@gmail.com> writes:
> >  
> >> Hi,
> >>
> >> I would like to start using a dedicated stack for system reset interrupt
> >> and treat it as a Linux nmi, which makes it tricky to call complex
> >> interrupt handlers directly from the system reset trap handler.
> >>
> >> So I would like to remove the decrementer and external handler calls from
> >> Cell and Pasemi platforms' system reset handler. I think we can just
> >> remove them if they can be handled when they re-fire as normal interrupts?
> >> At the moment I don't have environments set up to test if this works.  
> >
> > My QS22 has booted OK with it applied, so it seems OK.
> >
> > I'll test it a bit more tomorrow.  
> 
> OK, seems fine, and I have a trace that shows it's definitely going
> through that path:

Thanks for testing it.

>  1)               |    .default_idle_call() {
>  1)               |      .arch_cpu_idle() {
>  1)               |        .cbe_power_save() {
>  1)   0.128 us    |          .prep_irq_for_idle();
>  1)               |          .system_reset_exception() {
>  1)   0.512 us    |            .cbe_system_reset_exception();
>  1)   6.016 us    |          }
>  1)               |          .do_IRQ() {

It seems to do the right thing. I think decrementer should be working
proprely by setting it to 1 to get another exception?

In that case I will add a changelog and submit the patch.

Thanks,
Nick