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

[Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>]

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?

However, for Seattle, I would still need to provide the 
"platform.[reset|poweroff] ops since it's not full PSCI-0.2 (yet).

Suravee