On Wednesday, September 22, 2010 03:48:44 pm Yinghai Lu wrote:
> On 09/22/2010 02:22 PM, tip-bot for Bjorn Helgaas wrote:
> > Commit-ID: e72a6c8f7ac715a9cdb473afbc30743348d0a1e2
> > Gitweb: http://git.kernel.org/tip/e72a6c8f7ac715a9cdb473afbc30743348d0a1e2
> > Author: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
> > AuthorDate: Wed, 22 Sep 2010 14:15:47 -0600
> > Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> > CommitDate: Wed, 22 Sep 2010 13:29:39 -0700
> >
> > x86, pci: Ignore any PCI BARs that match an HPET we already know about
> >
> > We often discover the HPET early, via the static ACPI HPET table,
> > before enumerating PCI devices. If the HPET is implemented as a PCI
> > function, we will discover it again during PCI device enumeration. We
> > must ignore the PCI function so we don't inadvertently move it out
> > from under the driver.
> >
> > I think it's better to ignore *any* PCI BAR that matches a previously
> > discovered HPET; that way we don't need platform-specific knowledge,
> > and we won't have to add more quirks for future machines.
> >
> > This is for a regression from 2.6.34, but the reporter has been
> > unable to test it yet.
> >
> > [ hpa: if this fixes the regression, it should be promoted to x86/urgent ]
> >
> > Reference: https://bugzilla.kernel.org/show_bug.cgi?id=18482
> > Reported-by: Simon Arlott <simon@xxxxxxxxxxx>
> > Signed-off-by: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
> > LKML-Reference: <20100922201547.3197.33702.stgit@xxxxxxx>
> > Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> > ---
> > arch/x86/kernel/quirks.c | 21 +++++++++++++++++++++
> > arch/x86/pci/fixup.c | 28 ----------------------------
> > 2 files changed, 21 insertions(+), 28 deletions(-)
> >
> > diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
> > index 939b9e9..99a7d4b 100644
> > --- a/arch/x86/kernel/quirks.c
> > +++ b/arch/x86/kernel/quirks.c
> > @@ -507,6 +507,27 @@ static void force_disable_hpet_msi(struct pci_dev *unused)
> > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
> > force_disable_hpet_msi);
> >
> > +static void disable_pci_hpet(struct pci_dev *dev)
> > +{
> > + int i;
> > +
> > + if (!hpet_address)
> > + return;
> > +
> > + for (i = 0; i < 6; i++) {
> > + struct resource *res = &dev->resource[i];
> > +
> > + if (resource_type(res) == IORESOURCE_MEM &&
> > + res->start == hpet_address) {
> > + dev_info(&dev->dev, "BAR %d: %pR is an HPET we found earlier; ignoring this BAR\n",
> > + i, res);
> > + res->flags = 0;
> > + res->start = 0;
> > + res->end = 0;
> > + }
> > + }
> > +}
>
> It seems there is some problem here:
>
> hpet_res is inserted to resource with late_initcall().
> so if you don't touch that hpet address in bar and not put in the resource.
> kernel could allocate that address to other devices that doesn't get resource from BIOS.
Hmm, yes, that's a problem. Let me look into it tomorrow; maybe we
can do something like setting IORESOURCE_PCI_FIXED instead of just
clearing out the resource.
Bjorn
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