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SubjectRe: 2.6.7-rc1 breaks forcedeth


On Sun, 6 Jun 2004 ktech@wanadoo.es wrote:
>
> 2.6.7rc
>
> ------------
> CPU0
> 0: 163490 XT-PIC timer
> 1: 170 XT-PIC i8042
> 2: 0 XT-PIC cascade
> 5: 0 XT-PIC Bt87x audio
> 7: 0 XT-PIC NVidia nForce2
> 8: 2 XT-PIC rtc
> 9: 0 XT-PIC acpi
> 11: 100000 XT-PIC ehci_hcd
> 12: 1162 XT-PIC i8042
> 14: 14766 XT-PIC ide0
> 15: 18 XT-PIC ide1
> NMI: 0
> ERR: 0

This doesn't show the forcedeth driver at all. Not on irq11 (where it
should be), and not anywhere else either.

The thing is, the driver seems to not actually even register the irq
handler until the device is opened, which seems a bit bogus. It will
certainly result in problems if the device ever sends an interrupt. And
that seems to be exactly the behaviour you see.

I suspect that the driver should at the very least make sure to disable
any potentially pending interrupts in the "nv_probe()" function. I have no
idea how to do that, but it looks like something like

writel(0, base + NvRegIrqMask);
writel(NVREG_IRQSTAT_MASK, base + NvRegIrqStatus);

should probably do it. It would be better to reset the thing completely,
methinks, but whatever.

Anyway, this really looks very much like an irq is pending on the ethernet
controller, and isn't cleared, and then when the USB driver registers the
same irq (which was previously masked because nobody had actually
registered it), you get a storm of irq's.

As to _why_ this happens only with the current kernel, I don't know. Might
be an irq level/edge issue.

It would be interesting to have the forcedeth driver print out the irq it
will use in nv_probe, just to verify that it's 11. So when it currently
just says "forcedeth.c: subsystem: %05x:%04x bound to %s", make it print
out "dev->irq" too..

Linus
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