Re: [Xen-devel] [PATCH 3/4] xen/arm: Add PSCI system_off and system_reset support

[Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx>]

On 10/1/2014 9:46 AM, Ian Campbell wrote:
> On Wed, 2014-10-01 at 09:15 -0500, Suravee Suthikulpanit wrote:
> > On 10/01/2014 05:26 AM, Ian Campbell wrote:
> > > On Wed, 2014-10-01 at 11:07 +0100, Stefano Stabellini wrote:
> > > > > diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
> > > > > index b6360d5..b0d94a8 100644
> > > > > --- a/xen/arch/arm/psci.c
> > > > > +++ b/xen/arch/arm/psci.c
> > > > > @@ -58,6 +58,16 @@ int call_psci_cpu_on(int cpu)
> > > > >                                    cpu_logical_map(cpu), __pa(init_secondary), 
> > > > > 0);
> > > > >    }
> > > > >
> > > > > +void call_psci_system_off(void)
> > > > > +{
> > > > > +    __invoke_psci_fn_smc(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
> > > > > +}
> > > > > +
> > > > > +void call_psci_system_reset(void)
> > > > > +{
> > > > > +    __invoke_psci_fn_smc(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
> > > > > +}
> > > > This assumes PSCI 0.2 but actually the cpu_on function is still reading
> > > > the id from device tree.
> > > > Could you please change that too for uniformity?
> > Sure, I can add that.
> >
> > > There's actually quite a bit more required, detecting the DT compat
> > > string for v0.2 and following the updated bindings for that case.
> > >
> > > Having done that we need to use the 0.2 function ids for the existing
> > > calls too. And these new calls need to check that 0.2 is present and
> > > fail on 0.1.
> > >
> > > Ian.
> > So, it seems that minimally, we would need support for all PSCI-0.2
> > functions except MIGRATION. Also, once the system uses "arm,psci-0.2",
> > the power_off and reset code path should hook into the PSCI interface by
> > default.Does this sound right?
> Yes.
>
> > However, for Seattle, I would still need to provide the
> > "platform.[reset|poweroff] ops since it's not full PSCI-0.2 (yet).
> OOI is it also PSCI-0.1 compatible?
>
> Implementing the full PSCI 0.2 support is the thing I'm more worried
> about wrt the release, since it is likely to be the large bit of new
> work and it might not meet with Release Manager approval.
>
> Ian.
No, the only functions the firmware handles are just the system_off / 
system_reset (work in progress).
If you concern about changes to the PSCI subsystem, I could probably 
just making SMC call directly the platforms/seattle.c, until we have 
full PSCI-0.2 support ready in the arch/arm/psci.c
Suravee


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