Re: [PATCH v2] ACPI: Leave Bus Master Arbitration enabled for suspend/resume

[Rafael J. Wysocki]

On Sunday, July 08, 2012, Octavio Alvarez wrote:
> On Sun, 08 Jul 2012 13:08:19 -0700, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> 
> >> This is an old suspend/resume lockup fix:
> >>
> >> 	commit 2780cc4660e1
> >> 	Author: Len Brown <len.brown@xxxxxxxxx>
> >> 	Date:   Thu Dec 23 13:43:30 2004 -0500
> >>
> >> 	    [ACPI] Fix suspend/resume lockup issue
> >> 	    by leaving Bus Master Arbitration enabled.
> >> 	    The ACPI spec mandates it be disabled only for C3.
> >>
> >> The bug snuck back in in commit 2feec47d4c5f (ACPICA: ACPI 5: Support
> >> for new FADT SleepStatus, SleepControl registers, 2012-02-14),
> >> presumably by copy/pasting a copy of the code without that fix for the
> >> legacy case.
> >>
> >> On affected machines, after that commit, the machine locks up hard on
> >> resume from suspend.  The same fix as seven years ago still works.
> >>
> > Applied to the linux-next branch of the linux-pm.git tree.
> >
> > I think I'll push it for v3.6, since the bug is serious and is a  
> > regression.
> >
> > Bob, I think we should incorporate this into ACPICA, shouldn't we?
> 
> This bug affects since 3.4. I'd like to ask for this to be applied in the
> stable branches too, considering Jonathan's comments that this is a replay
> of an old and proven fix.
> 
> (I don't know if 3.3 is affected too. I know 3.2 is not affected by this.)

The problem seems to have been introduced during the 3.4 development cycle,
so v3.3 shouldn't be affected by it too.

Thanks,
Rafael
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