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

From: Greg KH
Date: Sat Oct 14 2006 - 01:22:46 EST


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@xxxxxx> 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@xxxxxx>
> >
> > 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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