linux-kernel - Re: 2.6.25-rc2 System no longer powers off after suspend-to-disk. Screen becomes green.

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Date:	Wed, 20 Feb 2008 12:41:30 -0800
From:	Jesse Barnes <jesse.barnes@...el.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Jeff Chua <jeff.chua.linux@...il.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Dave Airlie <airlied@...ux.ie>, linux-acpi@...r.kernel.org,
	suspend-devel List <suspend-devel@...ts.sourceforge.net>,
	Greg KH <gregkh@...e.de>
Subject: Re: 2.6.25-rc2 System no longer powers off after suspend-to-disk. Screen becomes green.

On Wednesday, February 20, 2008 12:29 pm Linus Torvalds wrote:
> On Wed, 20 Feb 2008, Rafael J. Wysocki wrote:
> > I think we should export the target sleep state somehow.
>
> Yeah. By *not* using "->suspend()" for freezing or hibernate.
>
> Please, Rafael - just make the f*cking suspend-to-disk use other routines
> already. 99% of all hardware needs to do exactly *nothing* on
> suspend-to-disk, and the ones that really do need things tend to need to
> not do a whole lot.

In talking with Rafael on IRC about this, I think we're agreed that we need 
separate entry points.  Even with a kexec based hibernate, we'll probably 
want ->hibernate callbacks so we don't end up shutting down the device.

The current callback system looks like this (according to Rafael and the last 
time I looked):
  ->suspend(PMSG_FREEZE)
  ->resume()
  ->suspend(PMSG_SUSPEND)
  *enter S3 or power off*
  ->resume()
The fact that we get suspend/resume called once before suspend again in the 
hibernate case is somewhat obnoxious, but it's even worse that we don't know 
what we're about to enter after ->suspend(PMSG_SUSPEND).  So in the short 
term it would be nice to at least get the target state exported.

And in the long term we could have:
  ->suspend()
  *enter S3*
  ->resume()
or:
  ->hibernate()
  *kexec to another kernel to save image*
  *power off*
  ->return_from_hibernate() (or somesuch)

Jesse
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