linux-kernel - Re: PCI PM: Restore standard config registers of all devices early

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Date:	Tue, 03 Feb 2009 12:12:05 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jesse Barnes <jesse.barnes@...el.com>,
	Andreas Schwab <schwab@...e.de>, Len Brown <lenb@...nel.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: PCI PM: Restore standard config registers of all devices early

On Mon, 2009-02-02 at 16:28 -0800, Linus Torvalds wrote:
> 
> On Tue, 3 Feb 2009, Rafael J. Wysocki wrote:
> > 
> > BTW, on the PMAC the problematic driver appears to be the radeon driver,
> > according to Ben, and the breakage is not related to USB.

> Hmm. atyfb_base.c has the same kind of things with magic PMAC code, but it 
> doesn't follow the USB pattern - it just replaces "pci_set_power_state()" 
> _entirely_. 

radeonfb_pm.c is the culprit here, I haven't looked at atyfb (mach64)
yet, but it has similar issues yes. I just attached a patch to the BZ
cleaning up radeonfb. I can have a look at doing a similar cleanup to
atyfb and aty128fb next.

> It seems a very interesting suspend routine, btw. It doesn't seem to do 
> any of the pci_save_state() at all, just re-initializes from scratch. 
> Maybe it is unhappy with the PM layer deciding to try to restore state 
> since it clearly didn't..

Well, I wrote that so ... :-) bear in mind that this code was mostly
written way before the PCI layer knew how to save and restore state.
Also, atyfb has some cases of chips that don't support PCI D states but
use private MMIO register to control suspend/resume.

Anyway, my proposed radeonfb patch is at:

 http://bugzilla.kernel.org/attachment.cgi?id=20085

I'll look at cleaning up atyfb and aty128fb later today if needed.

Cheers,
Ben.

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