[RFC] how to implement suspend to ram for arm64?

[RFC] how to implement suspend to ram for arm64?

[Jisheng Zhang]

Hi list,

we need the suspend to ram feature on arm64. And I think the fundamental code
is ready, for example  __cpu_suspend() etc.

However, there are several issues need to be resolved...

1. where to put platform_suspend_ops implementation? drivers/power?

2. If the "put ddr to self refresh" code must be in EL3 or secure EL1, how
linux tell the firmware to trigger it? extend PSCI or use the context_id
of PSCI CPU_SUSPEND function?

3. where to put the cod of invoke suspend_to_ram psci call?

Thanks in advance,
Jisheng

[RFC] how to implement suspend to ram for arm64?

[Lorenzo Pieralisi]

Hi Jisheng,

On Thu, Jan 08, 2015 at 11:54:08AM +0000, Jisheng Zhang wrote:
> Hi list,
> 
> we need the suspend to ram feature on arm64. And I think the fundamental code
> is ready, for example  __cpu_suspend() etc.
> 
> However, there are several issues need to be resolved...
> 
> 1. where to put platform_suspend_ops implementation? drivers/power?
> 
> 2. If the "put ddr to self refresh" code must be in EL3 or secure EL1, how
> linux tell the firmware to trigger it? extend PSCI or use the context_id
> of PSCI CPU_SUSPEND function?
> 
> 3. where to put the cod of invoke suspend_to_ram psci call?

We are working on all the items you mentioned above, inclusive of a PSCI spec
update.

I will make sure we post the required code on the lists shortly, and keep
you in the loop.

Thanks,
Lorenzo

[RFC] how to implement suspend to ram for arm64?

[Jisheng Zhang]

Dear Lorenzo,

On Thu, 8 Jan 2015 05:49:26 -0800
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:

> Hi Jisheng,
> 
> On Thu, Jan 08, 2015 at 11:54:08AM +0000, Jisheng Zhang wrote:
> > Hi list,
> > 
> > we need the suspend to ram feature on arm64. And I think the fundamental
> > code is ready, for example  __cpu_suspend() etc.
> > 
> > However, there are several issues need to be resolved...
> > 
> > 1. where to put platform_suspend_ops implementation? drivers/power?
> > 
> > 2. If the "put ddr to self refresh" code must be in EL3 or secure EL1, how
> > linux tell the firmware to trigger it? extend PSCI or use the context_id
> > of PSCI CPU_SUSPEND function?
> > 
> > 3. where to put the cod of invoke suspend_to_ram psci call?
> 
> We are working on all the items you mentioned above, inclusive of a PSCI
> spec update.
> 
> I will make sure we post the required code on the lists shortly, and keep
> you in the loop.
> 

Wow, great! Thank you very much. I have an ugly hack in private repo to support
this feature. I'm sure the hack will be definitely rejected :D 

Looking forward to the beautiful standard solution!

Thanks,
Jisheng