linux-kernel - Re: x86: Increase PCIBIOS_MIN_IO to 0x1500 to fix nForce 4 suspend-to-RAM

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Message-Id: <200712251511.41296.rjw@sisk.pl>
Date:	Tue, 25 Dec 2007 15:11:40 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Carlos Corbacho <carlos@...angeworlds.co.uk>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	Robert Hancock <hancockr@...w.ca>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...e.de>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Len Brown <lenb@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: x86: Increase PCIBIOS_MIN_IO to 0x1500 to fix nForce 4 suspend-to-RAM

On Tuesday, 25 of December 2007, Carlos Corbacho wrote:
> On Tuesday 25 December 2007 13:26:12 Rafael J. Wysocki wrote:
> > Well, citing from the ACPI 2.0 specification, section 9.1.6 Transitioning
> > from the Working to the Sleeping State (which is what we're discussing
> > here):
> >
> > 3. OSPM places all device drivers into their respective Dx state. If the
> > device is enabled for wake, it enters the Dx state associated with the wake
> > capability. If the device is not enabled to wake the system, it enters the
> > D3 state.
> > 4. OSPM executes the _PTS control method, passing an argument that
> > indicates the desired sleeping state (1, 2, 3, or 4 representing S1, S2,
> > S3, and S4).
> >
> > My opinion is that we should follow this part of the specification and so
> > we do.
> 
> This is that same section from ACPI 1.0B:
> 
> 3. The OS executes the Prepare To Sleep (_PTS) control method, passing an
> argument that indicates the desired sleeping state (1, 2, 3, or 4 representing
> S1, S2, S3, and S4).
> 
> 4. The OS places all device drivers into their respective Dx state. If the
> device is enabled for wakeup, it enters the Dx state associated with the 
> wakeup capability. If the device is not enabled to wakeup the system, it 
> enters the D3 state.
> 
> The DSDTs in question also claim ACPI 1.0 compatiblity.
> 
> > You're wrong, sorry.
> 
> No, I'm not entirely wrong - read the 1.0 spec, and read section 7.3.2 of the 
> ACPI 2.0 spec.
> 
> * ACPI 1.0 is very clear - we are breaking the 1.0 spec

By following the 2.0 and later ones.  Well ...

> * ACPI 2.0 is contradictory - section 7.3.2 repeats 1.0 ad verbatim (which is 
> what I quote in reply to Robert Hancock), but as you point out, 9.3.2 says 
> the opposite.
> 
> So, 1.0 and 3.0 are very clear and rather different on this, and 2.0 is 
> contradictory (and I presume this is one of the points ACPI 3.0 set out to 
> clean up).
> 
> I will rescind my point on ACPI 2.0 - I don't know what we should or shouldn't 
> be doing there, the spec is unclear.

I think we should follow section 9.3.2 that is explicit and has been reiterated
in the 3.0 specification.

> But for ACPI 1.0, we are doing the wrong thing.

Yes, we are.

OK, I think we can rearrange things to call _PTS early for ACPI 1.0x-compliant
systems.

Thanks,
Rafael
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