linux-kernel - Re: commit "radeonfb: Fix resume from D3Cold on some platforms" breaks resume from RAM on PowerBook

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Message-ID: <20090310213027.GB6272@soziologie.ch>
Date:	Tue, 10 Mar 2009 22:30:27 +0100
From:	Gaudenz Steinlin <gaudenz@...iologie.ch>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: commit "radeonfb: Fix resume from D3Cold on some platforms"
	breaks resume from RAM on PowerBook

On Tue, Mar 10, 2009 at 09:37:44AM +1100, Benjamin Herrenschmidt wrote:
> On Fri, 2009-03-06 at 12:41 +0100, Gaudenz Steinlin wrote:
> 
> > > Another thing you can try in radeonfb_pci_resume():
> > > 
> > >         if (pdev->dev.power.power_state.event == PM_EVENT_SUSPEND) {
> > > +		pci_restore_state(pdev);
> > 
> > Adding this fixes the bug. Apparently the PCI core does not fully
> > restore the state. Before your suggestions I also tried to find out
> > which part of your commit breaks resume and I found out that if I
> > reinsert the parts to save and restore the pci configuration the bug is
> > fixed. It seems that somehow the PCI coniguration is not fully restored [1].  
> 
> Ok so this doesn't make sense to me at this stage... I see two
> possibilities:
> 
>  1- You haven't properly done the test disabling the early resume hack
> (ie, you may have done it with also CPU_FREQ disabled for example) and
> got a false negative there. The platform code calls into the early
> resume stuff before the PCI core gets a chance to restore things so that
> would be an explanation. I'll send a patch fixing that.
> 
> or
> 
>  2- For some reason, the core call to pci_raw_set_power_state() from
> pci_restore_standard_config() is returning an error. That would cause
> the later not to restore the rest of the config.
> 
> So what I suggest is that while keeping your added pci_restore_state()
> in there, you also add some printk's in pci_restore_standard_config() to
> see anything weird happens in there or if it appears to properly call
> pci_restore_state(). It would be useful for us to know.

Are you still interested in these tests after that disabling the early
resume hack fixed things? I can try my best to test and add printk's but
it will probably take some time because I can't constantly reboot my
computer and still do some usefull work...

Gaudenz


-- 
Ever tried. Ever failed. No matter.
Try again. Fail again. Fail better.
~ Samuel Beckett ~
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