Re: [patch 1/4] Make usb_hcd_irq available for multi-role USB controllers with a shared interrupt line

Alan Stern <[email protected]>
Newsgroups gmane.linux.usb.devel
Message-ID <[email protected]>
On Thu, 26 Apr 2007, Peter Korsgaard wrote:

> Some multi-role (host/peripheral) USB controllers use a shared interrupt
> line for all parts of the chip. Export usb_hcd_irq so drivers can call it
> from their interrupt handler instead of duplicating code.
> Drivers pass an irqnum of 0 to usb_add_hcd to signal that the interrupt handler
> shouldn't be registerred by the core.

There was some controversy about this sort of thing in the past, and I 
don't remember what the outcome was.  The difficulty is that 0 is 
potentially a valid IRQ number, so it shouldn't be used to mean "don't 
register the IRQ handler".

Alan Stern


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