netdev - Re: [PATCH 5/7] pci: Export the pci_restore_msi

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Date:	Mon, 22 Oct 2007 11:49:24 +1000
From:	Michael Ellerman <michael@...erman.id.au>
To:	David Miller <davem@...emloft.net>
Cc:	mcarlson@...adcom.com, netdev@...r.kernel.org,
	linux-pci@...ey.karlin.mff.cuni.cz, linas@...tin.ibm.com,
	mchan@...adcom.com, linuxppc-dev list <linuxppc-dev@...abs.org>
Subject: Re: [PATCH 5/7] pci: Export the pci_restore_msi_state() function

On Sun, 2007-10-21 at 16:21 -0700, David Miller wrote:
> From: "Matt Carlson" <mcarlson@...adcom.com>
> Date: Fri, 19 Oct 2007 14:36:56 -0700
> 
> > This patch exports the pci_restore_msi_state() function.  This function
> > is needed to restore the MSI state during PCI error recovery.
> > 
> > Signed-off-by: Linas Vepstas <linas@...tin.ibm.com>
> > Signed-off-by: Matt Carlson <mcarlson@...adcom.com>
> > Signed-off-by: Michael Chan <mchan@...adcom.com>
> 
> I'm not so sure about this.

On pseries there's a chance it will work for PCI error recovery, but if
so it's just lucky that firmware has left everything configured the same
way. For actual suspend/resume it will never work, we need to ask
firmware to configure things.

> Perhaps, instead, you should do a pci_msi_disable() and
> pci_msi_enable() in the error detection and recovery sequence.

Yes I think so. That way we can properly reconfigure via the firmware
interface. The other option would be to design some new arch hook to do
resume, but just doing a disable/enable seems simpler to me.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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