Re: 2.6.7-rc1 breaks forcedeth

[Linus Torvalds <torvalds@osdl.org>]

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