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

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Date:	Fri, 6 Mar 2009 12:41:49 +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 Fri, Mar 06, 2009 at 08:57:20PM +1100, Benjamin Herrenschmidt wrote:
> 
> > So you are able to resume with my minimal config + CPU_FREQ? This would
> > be really strange if it is really the exact same model.
> 
> Yes, it appears to be :-)
> 
> > To verify if we really have the same model I included some data below. I
> > also included the gcc and binutils versions.
> > 
> > Please tell me if you have any further ideas on what to test.
> 
> In the commmit your revert, I added a function that "tests" if the chip
> appears to need to be POSTed: radeon_check_power_loss(). Try commenting
> out the content and make it always return 1.

This does not help.

> 
> 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].  

> +		pci_enable_device(pdev);

This does not help.

> +		pci_set_master(pdev);

This does not help.

Gaudenz

[1] These are just my wild guesses. I don't really understand much of
the code involved.

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