Re: Re: Fw: Anybody? 2.6.11 (stable and -rc) ACPI breaks USB

Li Shaohua
2005-03-17T01:33:37Z

Hi,
On Thu, 2005-03-17 at 00:10, Bjorn Helgaas wrote:
> On Tue, 2005-03-15 at 16:02 -0700, Zwane Mwaikambo wrote:
> > On Tue, 15 Mar 2005, Bjorn Helgaas wrote:
> > > That seems awfully suspicious to me. So the following is
> > > probably safe as far as it goes, but not sufficient for all
> > > cases.
> >
> > VIA bridges allow for IRQ routing updates by programming
> > PCI_INTERRUPT_LINE, so it is supposed to work even if we do it for
> all the
> > devices, so it appears to be a board/bios specific problem.
>
> This just feels like a sledgehammer approach, i.e., we're
> programming PCI_INTERRUPT_LINE in more cases that we actually
> need to. I especially don't like that any Via device with
> devfn==0 triggers the quirk. That doesn't seem like the
> right test if we're really looking for a Via bridge.
>
> > > -static void __devinit quirk_via_bridge(struct pci_dev *pdev)
> > > +static void __devinit quirk_via_irqpic(struct pci_dev *dev)
> > > {
> > > - if(pdev->devfn == 0) {
> > > - printk(KERN_INFO "PCI: Via IRQ fixup\n");
> > > - via_interrupt_line_quirk = 1;
> > > + u8 irq, new_irq = dev->irq & 0xf;
> > > +
> > > + pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq);
> > > + if (new_irq != irq) {
> > > + printk(KERN_INFO "PCI: Via IRQ fixup for %s, from %d
> to %d\n",
> > > + pci_name(dev), irq, new_irq);
> > > + udelay(15);
> > > + pci_write_config_byte(dev, PCI_INTERRUPT_LINE,
> new_irq);
> > > }
> > > }
> > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA,
> PCI_ANY_ID, quirk_via_bridge );
> > > +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_82C586_2, quirk_via_irqpic);
> > > +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_82C686_5, quirk_via_irqpic);
> > > +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_82C686_6, quirk_via_irqpic);
> > > +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_8233_5, quirk_via_irqpic);
> > > +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_8233_7, quirk_via_irqpic);
> >
> > This looks like it'll only affect the PCI device associated with the
> > listed south bridges, which might break systems which relied on the
> per
> > device setting. Your 'debug' patch actually made sense to me, that
> is,
> > moving the PCI_INTERRUPT_LINE fixup at gsi register.
>
> Yes, that's what I meant by the above probably not being sufficient.
>
> The main thing the debug patch did was to move the write to after
> the IOAPIC programming. (And I think it added back the mysterious
> udelay().) My point is that the write could just as easily be done
> in a pci_enable fixup, because that also happens after the IOAPIC
> update.
The comments in previous quirk said it's required only in PIC mode.

>
> The quirk would have to be something like this:
>
> static void __devinit quirk_via_irq(struct pci_dev *dev)
> {
> if (!via_interrupt_line_quirk)
> return;
>
> /* update PCI_INTERRUPT_LINE */
> ...
> }
> DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID,
> quirk_via_irq);
>
> with a PCI_FIXUP_HEADER quirk that sets via_interrupt_line_quirk when
> we find a Via bridge.
>
> But I'm uneasy even about this -- what if there are multiple bridges,
> with only one of them being a Via? Why would we want to apply this
> quirk to the devices under the non-Via bridges? Wouldn't it be better
> to search up the hierarchy of each device, looking for a Via bridge,
> and apply the quirk only if we find one?
I feel we concerned too much. Changing the interrupt line isn't harmful,
right? Linux actually ignored interrupt line. Maybe just a
PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_ANY_ID, quirk_via_irq) is
sufficient.
and
quirk_via_irq(..)
{
update_interrupt_line
}

Thanks,
Shaohua