Re: [PATCH,RFC] quirks for VIA VT8237 southbridge

[Karsten Wiese]

Am Dienstag, 16. August 2005 00:31 schrieb Bjorn Helgaas:
> These patches seem unrelated except that they both contain the
> text "via", so I think you should at least split them.

Will do.

> This quirk_via_irq() change seems like an awful lot of work to
> get rid of a few log messages.  In my opinion, it's just not
> worth it, because it's so hard to debug problems in that area
> already.

What about the following version?
quirk_via_686irq() only works on pci_devs that are part of the 686.
Sooner or later there'll be more VIA southbridge types, which will
not need quirk_via_irq() like the 8237.

------
/*
 * Via 686A/B:  The PCI_INTERRUPT_LINE register for the on-chip
 * devices, USB0/1, AC97, MC97, and ACPI, has an unusual feature:
 * when written, it makes an internal connection to the PIC.
 * For these devices, this register is defined to be 4 bits wide.
 * Normally this is fine.  However for IO-APIC motherboards, or
 * non-x86 architectures (yes Via exists on PPC among other places),
 * we must mask the PCI_INTERRUPT_LINE value versus 0xf to get
 * interrupts delivered properly.
 */
static void quirk_via_686irq(struct pci_dev *dev)
{
	u8 irq, new_irq;
		/*
		 * The ISA bridge is used to identify the 686.
		 * It shares it's PCI slot and bus with the device under test
		 * and is assigned to function 0.
		 */
	unsigned int isa_bridge_devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 0);
	struct pci_dev * isa_bridge = pci_find_slot(dev->bus->number, isa_bridge_devfn);
		
	if (isa_bridge == NULL || isa_bridge->vendor != PCI_VENDOR_ID_VIA ||
	    isa_bridge->device != PCI_DEVICE_ID_VIA_82C686)
		return;		/* We are not on a 686. Lets leave */

	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);	/* unknown if delay really needed */
		pci_write_config_byte(dev, PCI_INTERRUPT_LINE, new_irq);
	} 
}
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_1, quirk_via_686irq);
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_2, quirk_via_686irq);
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_4, quirk_via_686irq);
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_5, quirk_via_686irq);
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_6, quirk_via_686irq);
------

We could also add a "pci_dev * housed_in;" to "struct pci_dev"
to get rid of search done above under pci_find_slot().
To fill in "pci_dev * housed_in;", we'd need another quirk though.

Side note 1: IIRC via82xxx IDE code could also make use of such a "pci_dev * housed_in;"

Side note 2: The members
./include/linux/pci.h:542:	unsigned short vendor_compatible[DEVICE_COUNT_COMPATIBLE];
./include/linux/pci.h:543:	unsigned short device_compatible[DEVICE_COUNT_COMPATIBLE];
of "struct pci_dev" are unused in the current kernel and can vanish.
So a new "pci_dev * housed_in;" in "struct pci_dev" wouldn't add code in the sum.

   Karsten

	

	
		
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