Re: USB lockup on Thinkpad i1300

[Alan Cox]

> load usb-ohci. Tracing with kdb shows that the system locks up right
> after executing this: (usb-ohci.c:2137)
> 
>         /* HC Reset requires max 10 ms delay */
>         writel (OHCI_HCR,  &ohci->regs->cmdstatus);
> 
> Anyone have any idea? The processor apparently never gets to the next
> instruction.
As an experiment stick

	unsigned long flags;

	save_flags(flags);
	cli();
	printh("Not dead yet\n");
	/* HC ...
	..

	printk("Writel returned\n");
	readl(&ohci->regs->cmdstatus);
	printk("Write definitely occurred now\n");
	restore_flags(flags);
	printk("Ok with IRQ on\n");

Into that piece of code.

That will tell you if for example it is an IRQ storm of some kind.