Re: [patch] PCI: disable MSI on more ATI NorthBridges

Jeff Garzik
2007-10-19T20:21:40Z

Linas Vepstas wrote:
> On Fri, Oct 19, 2007 at 09:17:23PM +0800, Shane Huang wrote:
>> Since we have little experience on PCI and MSI here, we had to try to
>
> As someone else pointed out, AMD should have *lots* of people with
> pci and msi experience on the payroll. (Folks here buy AMD-designed
> pci chips ...)
>
>> ONLY
>> comment out the pci_intx() call in drivers/ata/ahci.c
>> My system can boot up too with MSI enabled!
>>
>> So does it mean that the root cause is our SB700 SATA controller
>> has a hardware bug where setting INTX_DISABLE in the PCI COMMAND
>> register masks MSI interrupts too?
>
> That's what it sounds like, to me.
>
>> And what is the software solution or workaround?
>
> Not sure. Sounds like the device driver needs a quirk for this part.

Take a look at tg3.c net driver change
2fbe43f6f631dd7ce19fb1499d6164a5bdb34568 which is a similar situation.

However, it may turn out that removing the pci_intx() stuff as a general
rule is easier than quirking these devices, if enough of them turn out
to have this hardware bug.

The tg3.c change should illustrate how to fix immediately, though.

Jeff