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

Sudeep Holla
2017-02-21T18:27:59Z

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. And since I now better understand you problem,
you get extra NACK for this series ;)

--
Regards,
Sudeep