Re: [git pull request] ACPI patches for 2.6.34-rc6

Matthew Garrett
2010-05-11T17:25:55Z

On Fri, May 07, 2010 at 10:36:00PM +0100, Matthew Garrett wrote:
> On Fri, May 07, 2010 at 02:21:08PM -0700, Linus Torvalds wrote:
> > Well, is there any reason to have 'set_sci_en_on_resume' at all then?
>
> I'd hope not, but it depends on what Windows does on resume. If it
> doesn't do the SMM call and just does the register write instead, then
> it may be that some machines are on that list because the SMM call
> breaks them rather than because they need the register to be set by
> hand. I'm planning on instrumenting it to check, but haven't had time to
> do so yet.

I've now checked the behaviour of Windows. It turns out that it never
makes the ACPI enable SMM call on resume. This is consistent with
http://bugzilla.kernel.org/show_bug.cgi?id=13745 which shows a bug
being introduced by us making the enable call in the first place.
Merging my patch and removing the blacklist would re-break these
machines. Instead, we should just unconditionally set SCI_EN since this
is the tested configuration. I'll send a followup patch.

--
Matthew Garrett | mjg59@srcf.ucam.org