[PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power

[sudeep.holla@arm.com (Sudeep Holla)]

On 21/02/17 18:27, Sudeep Holla wrote:
> 
> 
> On 21/02/17 17:51, Sudeep Holla wrote:
>>
>>
>> On 21/02/17 17:34, Geert Uytterhoeven wrote:
> 
> [...]
> 
>>>
>>> The SoC can wake-up. It's just not guaranteed that it can wake-up using
>>> the wakeup-source configured from Linux. Which wakeup-sources are available
>>> depends on the actual PSCI implementation.  It's not specified by the PSCI
>>> specification.
>>>
>>>> Just botching whatever shallow state you can enter on a particular SoC
>>>> into standard "mem" state sounds *horrible* to me.
>>>
>>> That's more or less what /sys/power/mem_sleep does, though.
>>>
>>
>> OK, I will go through that in detail.
>>
> 
> OK, I went through the patch and the main intention is was added.
> So I will begin by summarizing my understanding:
> 
> A new suspend interface(/sys/power/mem_sleep) is added to allow the
> "mem" string in /sys/power/state to represent multiple things that can
> be selected.
> 
> Before:
> A. echo freeze > /sys/power/state ---> Enters s2idle
> B. echo mem > /sys/power/state ---> Enters s2r(a.k.a now deep mem sleep)
> 
> After:
> 1. echo freeze > /sys/power/state ---> Enters s2idle still same
> 2. echo s2idle > /sys/power/mem_sleep
>    echo mem > /sys/power/state ---> Also enter s2idle
> 3. echo deep > /sys/power/mem_sleep
>    echo mem > /sys/power/state ---> Also enter s2r(same as [B] above)
> 
> Please note I have carefully dropped standby/shallow as we will not
> support that state on ARM64 platforms(refer previous discussions for the
> same)
> 
> Now IIUC, you need 2 above. So, since this new interface allow mem to
> mean "s2idle", we need to fix the core to register default suspend_ops
> to achieve what you need. 

I take this back, you have everything you need in place, nothing needs
to be done. I just checked again. If I don't register PSCI suspend_ops,
I still get mem in /sys/power/state with s2idle in /sys/power/mem_sleep
which is exactly what we need. Again we don't support standby/shallow
state on ARM64/PSCI.

-- 
Regards,
Sudeep