linux-kernel - Re: [PATCH 1/2] [PCI] Check that MWI bit really did get set

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Date:	Fri, 13 Oct 2006 22:21:10 -0700
From:	Greg KH <gregkh@...e.de>
To:	Andrew Morton <akpm@...l.org>
Cc:	Matthew Wilcox <matthew@....cx>,
	Val Henson <val_henson@...ux.intel.com>,
	netdev@...r.kernel.org, linux-pci@...ey.karlin.mff.cuni.cz,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] [PCI] Check that MWI bit really did get set

On Fri, Oct 13, 2006 at 09:41:35PM -0700, Andrew Morton wrote:
> On Fri, 06 Oct 2006 13:05:18 -0600
> Matthew Wilcox <matthew@....cx> wrote:
> 
> > Since some devices may not implement the MWI bit, we should check that
> > the write did set it and return an error if it didn't.
> > 
> > Signed-off-by: Matthew Wilcox <matthew@....cx>
> > 
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index a544997..3d041f4 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -900,13 +900,17 @@ #endif
> >  		return rc;
> >  
> >  	pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > -	if (! (cmd & PCI_COMMAND_INVALIDATE)) {
> > -		pr_debug("PCI: Enabling Mem-Wr-Inval for device %s\n", pci_name(dev));
> > -		cmd |= PCI_COMMAND_INVALIDATE;
> > -		pci_write_config_word(dev, PCI_COMMAND, cmd);
> > -	}
> > -	
> > -	return 0;
> > +	if (cmd & PCI_COMMAND_INVALIDATE)
> > +		return 0;
> > +
> > +	pr_debug("PCI: Enabling Mem-Wr-Inval for device %s\n", pci_name(dev));
> > +	cmd |= PCI_COMMAND_INVALIDATE;
> > +	pci_write_config_word(dev, PCI_COMMAND, cmd);
> > +
> > +	/* read result from hardware (in case bit refused to enable) */
> > +	pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > +
> > +	return (cmd & PCI_COMMAND_INVALIDATE) ? 0 : -EINVAL;
> >  }
> >  
> >  /**
> 
> Bisection shows that this patch
> (pci-check-that-mwi-bit-really-did-get-set.patch in Greg's PCI tree) breaks
> suspend-to-disk on my Vaio.  It writes the suspend image and gets to the
> point where it's supposed to power down, but doesn't.
> 
> After a manual power-cycle it successfully resumes from disk, but
> networking (at least) is dead.

Ok, I'll drop this from my tree too.

Matthew, let me know whn you have a revised patch you wish to have me
include.

thanks,

greg k-h
-
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