Re: question on spurious interrupts

On Thu, 20 Sep 2007, Oliver Neukum wrote:

> Hi,
> 
> regarding this comment from ehci_irq:
> 
> #ifdef	EHCI_VERBOSE_DEBUG
> 	/* unrequested/ignored: Frame List Rollover */
> 	dbg_status (ehci, "irq", status);
> #endif
> 
> How are we supposed to get there if this code comes first:
> 
> 	status &= INTR_MASK;
> 	if (!status) {			/* irq sharing? */
> 		spin_unlock(&ehci->lock);
> 		return IRQ_NONE;
> 	}
> 
> Which chipset occur unrequested interrupts with? Shouldn't they
> be acknowledged and IRQ_HANDLED be returned?

I get the impression the code should look like this:

	if (!status) {			/* irq sharing? */
		spin_unlock(&ehci->lock);
		return IRQ_NONE;
	}

#ifdef	EHCI_VERBOSE_DEBUG
	/* unrequested/ignored: Frame List Rollover */
	dbg_status (ehci, "irq", status);
#endif

	/* clear (just) interrupts */
	status &= INTR_MASK;
	ehci_writel(ehci, status, &ehci->regs->status);
	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted write */
	bh = 0;

Alan Stern


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