From: "ext Shilimkar, Santosh" <redacted>
Subject: RE: [RFC][PATCH 1/1] ARM: Add initial hibernation support
Date: Fri, 16 Jul 2010 10:48:00 +0200

Hiroshi,

quoted

-----Original Message-----
From: linux-omap-owner at vger.kernel.org [mailto:linux-omap-
owner at vger.kernel.org] On Behalf Of Russell King - ARM Linux
Sent: Friday, July 16, 2010 1:23 PM
To: Hiroshi DOYU
Cc: linux-arm-kernel at lists.infradead.org; pavel at ucw.cz;
khilman at deeprootsystems.com; Reddy, Teerth; linux-pm at lists.linux-
foundation.org; Yoshiya.Hirase at nokia.com; linux-omap at vger.kernel.org
Subject: Re: [RFC][PATCH 1/1] ARM: Add initial hibernation support

On Thu, Jul 15, 2010 at 12:08:07PM +0300, Hiroshi DOYU wrote:

quoted

From: ext Russell King - ARM Linux <redacted>
Subject: Re: [RFC][PATCH 1/1] ARM: Add initial hibernation support
Date: Thu, 15 Jul 2010 10:41:18 +0200

quoted

On Thu, Jul 15, 2010 at 08:34:50AM +0300, Hiroshi DOYU wrote:

quoted

Russell, would it be possible to put this into your next merge queue?

I think it needs quite a bit of rework - I certainly don't like all
those CP15 register accesses there - that's asking for lots of ifdefs
to spring up as more CPUs are supported.

Eg, what about ensuring that state such as iWMMXt on PXA CPUs is
properly restored?

Right. This arch specific part can be something like
"suspend-v[3-7].S" to accomodate those differences

It's not quite that simple - things like iWMMXt aren't part of the ARM
arch specs.

quoted

quoted

We already have code which knows what needs to be saved across a
power-off transition - its what we use for our normal suspend/resume
functionality, so we should look at re-using that code for hibernate
as well.  We really don't want to be maintaining two sets of code
doing the same thing.

Could you explain which code you're refering for the existing one?

The code which handles saving state for the existing suspend/resume
support.  This code already saves the necessary state from CP15 and
any other state which needs to be saved prior to putting the system
into low power mode.

Every machine class which supports suspend today has their own chunk
of code which does this, normally called something like sleep.S

When this getting developed in TI, we had one more concern about handling
the trustzone part for the CP15 resgiters.
This patch will hang on restoration on some devices implementing trustzone.

Thanks for the info.

I think that this trustzone issue and PXA part can be revisited later
once the basic stuff is accepted.