how to enable suspend to ram for arm-64 bits

[Sudeep Holla]

On 22/08/16 15:41, yoma sophian wrote:
> hi Sudeep:
>
>>> Yes, I agree with you.
>>> But it may not mean the ONLY way for all armv8 platform that support
>>> suspend method is PSCI.
>>
>> I would say yes but if you have a real good reason not to adopt PSCI on
>> your platform then you can try present that. It should be convincing
>> enough to deviate from the standards :)
>
> Since we don't implement full features of PSCI on our platform, that
> is why we wants to know whether there is registration of platform
> suspend method.
>

For adding support for your platform in the mainline kernel, you need to
support SYSTEM_SUSPEND in psci. There's no other way currently with the
mainline.

> BTW, from the git log, it seems psci.c doesn't register system suspend
> until Linux 4.4.

Correct.

> if so, before 4.4, how aarch64 support such as str, echo mem >
> /sys/power/state , suspend flow?
>

You can back-port those patches, they are quite trivial if you need
it on pre-v4.4 kernel.

Moreover, how do you plan to support system system without PSCI ?
How will you let the higher exception softwares know that you are
entering system suspend. How will their context resumed back ?

-- 
Regards,
Sudeep