linux-kernel - Re: [PATCH] ACPI Suspend: Enable ACPI during resume if SCI

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Message-Id: <200810061445.33151.rjw@sisk.pl>
Date:	Mon, 6 Oct 2008 14:45:32 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Len Brown <lenb@...nel.org>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@...e.cz>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Thomas Renninger <trenn@...e.de>,
	Romano Giannetti <romano.giannetti@...il.com>
Subject: Re: [PATCH] ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On Monday, 6 of October 2008, Len Brown wrote:
> applied to acpi-test.

Thanks!

Actually, it appears to fix a recent regression for Romano
(http://bugzilla.kernel.org/show_bug.cgi?id=11634).  If that's verified, it
would be -stable material.

[I guess the regression was caused by the Linus' patch we were discussing on
IRC.]

It also evidently fixes my resume problem on the MSI Wind.  Both machines
(the Wind and the Romano's box) have the problem with ACPI not being enabled
by the BIOS on resume from S3.

Thanks,
Rafael


> On Sat, 4 Oct 2008, Rafael J. Wysocki wrote:
> 
> > From: Rafael J. Wysocki <rjw@...k.pl>
> > 
> > ACPI Suspend: Enable ACPI during resume if SCI_EN is not set
> > 
> > On some machines, like for example MSI Wind U100, the BIOS doesn't
> > enable ACPI before returning control to the OS, which sometimes
> > causes resume to fail.  This is against the ACPI specification,
> > which clearly states that "When the platform is waking from an S1, S2
> > or S3 state, OSPM assumes the hardware is already in the ACPI mode
> > and will not issue an ACPI_ENABLE", but it won't hurt to check the
> > SCI_EN bit and enable ACPI during resume from S3 if this bit is not
> > set.
> > 
> > Fortunately, we already have acpi_enable() for that, so use it in the
> > resume code path, before executing _BFS, in analogy with the
> > resume-from-hibernation code path.
> > 
> > NOTE: We aren't supposed to set SCI_EN directly, because it's owned
> > by the hardware.
> > 
> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > ---
> >  drivers/acpi/sleep/main.c |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > Index: linux-2.6/drivers/acpi/sleep/main.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/acpi/sleep/main.c
> > +++ linux-2.6/drivers/acpi/sleep/main.c
> > @@ -200,6 +200,8 @@ static int acpi_suspend_enter(suspend_st
> >  		break;
> >  	}
> >  
> > +	/* If ACPI is not enabled by the BIOS, we need to enable it here. */
> > +	acpi_enable();
> >  	/* Reprogram control registers and execute _BFS */
> >  	acpi_leave_sleep_state_prep(acpi_state);
> >  
> > 
> 
> 


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