Re: Thinkpad suspend-to-disk regression

["Guilherme Salgado" <gsalgado@gmail.com>]

On 5/2/07, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Wednesday, 2 May 2007 19:28, Guilherme Salgado wrote:
> > On 4/25/07, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > On Wednesday, 25 April 2007 04:25, Guilherme Salgado wrote:
> > > > On 4/24/07, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > > > On Tuesday, 24 April 2007 20:29, Guilherme Salgado wrote:
> > > > > > (I've already sent this to linux-acpi but got no response so far, so I
> > > > > > thought it could be a good idea to send directly to you)
> > > > > >
> > > > > > Hi there,
> > > > > >
> > > > > > I recently noticed that my thinkpad T60 would lose the sound after
> > > > > > being suspended to disk (https://launchpad.net/bugs/80893), requiring
> > > > > > a cold restart to fix it. After some git-bisect work I found this
> > > > > > regression was a consequence of
> > > > > > http://git.kernel.org/?p=linux/kernel/git/lenb/linux-acpi-2.6.git;a=commitdiff;h=9185cfa92507d07ac787bc73d06c42222eec7239
> > > > > > (patch inlined here)
> > > > > >
> > > > > > Is there any chance of fixing the regression this introduced without
> > > > > > reverting it? Please let me know if you want any other info or have a
> > > > > > patch for me to try.
> > > > >
> > > > > You don't need a patch, I think.  Please try
> > > > >
> > > > > # echo shutdown > /sys/power/disk
> > > > >
> > > > > before the suspend (assuming you use the built-in swsusp).  If that works,
> > > > > just make your configuration scripts echo 'shutdown' to /sys/power/disk at
> > > > > system startup.
> > > > >
> > > >
> > > > I use Ubuntu's default /etc/acpi/hibernate.sh, which already sets
> > > > /sys/power/disk to shutdown before echoing "disk" to /sys/power/state.
> > >
> > > In that case it's impossible that the commit you have identified causes the
> > > problem to happen.
> > >
> > > It doesn't even touch the 'shutdown' code path.
> >
> > Is it be possible that the change to /sys/power/disk is not doing what
> > it should? I think that's likely to be the case because I got a bunch
> > of people to try a kernel with the patch reverted and it fixed the
> > problem they were having.
> >
> > The most recent comments at https://bugs.launchpad.net/+bugs/80893 are
> > all confirming that the kernel at
> > http://rookery.ubuntu.com/~kyle/kernels/salgado/2007-04-25/ fixes
> > their problem.
> >
> > I'd be glad to do anything to further debug this if you can give me
> > some pointers.
>
> Well, the problem is that we have switched to the platform mode by default
> and "echo shutdown > /sys/power/disk" before the suspend should get the old
> behavior back
>

Right, that's why I asked if it'd be possible that echoing "shutdown"
to /sys/power/disk could somehow be a no-op in this case.

> Please try to apply the appended patch instead of reverting the entire commit
> and see if the problem is still present.
>

That works just fine, yes. Are you willing to change the default back
to PM_DISK_SHUTDOWN or should we find out why "echo shutdown >
/sys/power/disk" is not having the same effect as changing the
default, as it should?

Cheers,
Guilherme