Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations

[Chenhui Zhao]

On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@xxxxxxxxxxxxx> 
wrote:
> On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote:
> >  >
>
> >  On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood <scottwood@xxxxxxxxxxxxx>
> >  wrote:
>
> >  >
> >  > Could you explain irq_mask()?  Why would there still be IRQs 
> > destined
> >  > for
> >  > this CPU at this point?
> >
> >  This function just masks irq by setting the registers in RCPM (for
> >  example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to this CPU
> >  have been migrated to other CPUs.
>
> So why do we need to set those bits in RCPM?  Is it just caution?

Setting these bits can mask interrupts signalled to RCPM from MPIC as a 
means of
waking up from a lower power state. So, cores will not be waked up 
unexpectedly.

> >  > @@ -431,21 +415,9 @@ void __init mpc85xx_smp_init(void)
> >  > >                smp_85xx_ops.probe = NULL;
> >  > >        }
> >  > >
> >  > >  -     np = of_find_matching_node(NULL, mpc85xx_smp_guts_ids);
> >  > >  -     if (np) {
> >  > >  -             guts = of_iomap(np, 0);
> >  > >  -             of_node_put(np);
> >  > >  -             if (!guts) {
> >  > >  -                     pr_err("%s: Could not map guts node
> >  > > address\n",
> >  > >  -
> >  > > __func__);
> >  > >  -                     return;
> >  > >  -             }
> >  > >  -             smp_85xx_ops.give_timebase = 
> > mpc85xx_give_timebase;
> >  > >  -             smp_85xx_ops.take_timebase = 
> > mpc85xx_take_timebase;
> >  > >   #ifdef CONFIG_HOTPLUG_CPU
> >  > >  -             ppc_md.cpu_die = smp_85xx_mach_cpu_die;
> >  > >  +     ppc_md.cpu_die = qoriq_cpu_dying;
> >  > >   #endif
> >  >
> >  > Shouldn't you make sure there's a valid qoriq_pm_ops before 
> > setting
> >  > cpu_die()?  Or make sure that qoriq_cpu_dying() works regardless.
> >  >
> >  > -Scott
> >
> >  This patch is just for e500v2. The following patches will handle the
> >  case of e500mc, e5500 and e6500.
>
> What stops a user from trying to use cpu hotplug on unsupported cpus, 
> or in a
> virtualized environment, and crashing here?
>
> -Scott

Will set these callback functions only if qoriq_pm_ops is valid.

-Chenhui

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