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


On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@freescale.com>
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@freescale.com>
>> 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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