Re: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power
From: Sudeep Holla
Date: Tue Feb 21 2017 - 13:46:16 EST
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
>>>> 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.
> A. echo freeze > /sys/power/state ---> Enters s2idle
> B. echo mem > /sys/power/state ---> Enters s2r(a.k.a now deep mem sleep)
> 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
> 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.