Re: [Xen-devel] pv_ops dom0 kernel failure with ata_piix / irq problems

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sat, 2009-01-24 at 16:59 -0800, Jeremy Fitzhardinge wrote:
> Pasi KÃrkkÃinen wrote:
> > rc = devm_request_irq(dev, ATA_PRIMARY_IRQ(pdev), irq_handler, IRQF_SHARED, 
> > drv_name, host);
> > if (rc)
> >     goto out;
> >
> > and ports names never get assigned because that "goto out;" is executed.
> >
> > So.. Any ideas why devm_request_irq() fails? 
> 
> 
> Good question.  Will need to pick through
> 
> Hm, wonder if its something to do with the handling of the legacy irqs:
> 
> ata_pci_sff_activate_host: pci_read_config_byte()
> ata_pci_sff_activate_host: if (!devres_open_group(dev, NULL, GFP_KERNEL))
> ata_pci_sff_activate_host: if (!legacy_mode && pdev->irq)
> ata_pci_sff_activate_host: legacy_mode
> ata_pci_sff_activate_host: port 0 not dummy: devm_request_irq()
> ata_pci_sff_activate_host: non-legacy-mode irq: 30
> ata_pci_sff_activate_host: requesting ATA_PRIMARY_IRQ(pdev) irq: 14
> ata_pci_sff_activate_host: devm_request_irq() returned != 0, goto out

I see a similar failure to allocate IRQ 14 although in my case some
other driver comes along and makes it work so I hadn't noticed until
just now.

In my case request_irq() was being called direct rather than via
devm_request_irq and the return was -ENOSYS (it'd be interesting to know
what != 0 value was seen here). I followed this down to __setup_irq()
which has:
        if (desc->chip == &no_irq_chip)
                return -ENOSYS;

So it looks like something expects there to already be a chip present
for the legacy IRQ. For non-legacy IRQs I think we setup the chip
through xen_pci_pirq_enable() -> xen_register_gsi() ->
xen_allocate_pirq() -> set_irq_chip_and_handler_name(). Perhaps legacy
IRQs do not (always) get explicitly enabled?

This little hack made things work for me. Possibly the correct fix might
be to use xen_register_gsi() here instead of xen_allocate_pirq() and get
rid of the special case for IRQ 14 and 15 in xen_pci_pirq_enable().
Maybe only 14 and 15 need this special treatment.

--- a/arch/x86/xen/pci.c        Fri Jan 30 17:39:54 2009 +0000
+++ b/arch/x86/xen/pci.c        Fri Jan 30 18:08:36 2009 +0000
@@ -133,4 +133,7 @@
        /* Blerk. */
        acpi_gbl_FADT.sci_interrupt = irq;
 #endif
+
+       for (irq = 0 ; irq < 16 ; irq ++)
+               xen_allocate_pirq(irq);
 }



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