Re: Kernel 2.6.12 + IO-APIC + uhci_hcd = Trouble

From: Alan Stern
Date: Mon Jul 11 2005 - 13:43:25 EST


On Mon, 11 Jul 2005, Michel Bouissou wrote:

> Hi Nathalie,
>
> Thanks for your answer and pointer. Unfortunately it doesn't help.
>
> The patch you mention won't apply on my kernel alone, I need first to apply
> the patch from
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c434b7a6aedfe428ad17cd61b21b125a7b7a29ce ,
> then your patch applies OK.
>
> Unfortunately, it doesn't solve my issue. Booting this kernel still results in
> an interrupt issue with uhci_hcd.
>
> After boot, "cat /proc/interrupts" shows:
> CPU0
> 0: 188066 IO-APIC-edge timer
> 1: 308 IO-APIC-edge i8042
> 2: 0 XT-PIC cascade
> 4: 413 IO-APIC-edge serial
> 7: 3 IO-APIC-edge parport0
> 14: 1177 IO-APIC-edge ide4
> 15: 1186 IO-APIC-edge ide5
> 18: 1028 IO-APIC-level eth0, eth1
> 19: 8513 IO-APIC-level ide0, ide1, ide2, ide3, ehci_hcd:usb4
> 21: 100000 IO-APIC-level uhci_hcd:usb1, uhci_hcd:usb2, uhci_hcd:usb3
> 22: 0 IO-APIC-level VIA8233
> NMI: 0
> LOC: 187967
> ERR: 0
> MIS: 0
>
> (The problem is with IRQ 21 for uhci_hcd)
>
> (It is to note that without those patches, I didn't see any IRQ managed by
> "XT-PIC", all were managed by the IO-APIC...)

It's possible that the errors you're getting are caused by some other
device erroneously generating interrupt requests on IRQ 21. Then when
uhci-hcd enables that IRQ, there's no driver available to handle the
interrupts...

It's also possible that the UHCI controllers are generating the unwanted
interrupt requests. You should make sure that Legacy USB Support is
turned off in your BIOS settings. You can also try adding the
"usb-handoff" kernel parameter to your boot command line.

Alan Stern

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