IRQ #0 broken on ARM

Fri Nov 21 02:53:33 PST 2014

On Fri, Nov 21, 2014 at 10:34:56AM +0000, Russell King - ARM Linux wrote:
> On Fri, Nov 21, 2014 at 02:31:05PM +0400, Dmitry Eremin-Solenikov wrote:
> > Hello,
> > 
> > After the commit a71b092a9c68685a270ebdde7b5986ba8787e575
> > (ARM: Convert handle_IRQ to use __handle_domain_irq) IRQ #0 is broken
> > on ARM. It is a valid IRQ and it is quite imporant (on sa1100 it's a GPIO0).
> 
> No, it is not a valid IRQ.  (It was a mistake to think it was.)
> Generic code will always assume IRQ0 is not valid, and the fix is to
> fix the places in ARM where we try to use it.
To make this more understandable: Linux uses virtual irq numbers. The
virtual irq 0 is invalid. For a given irq domain the (hardware) irq 0 is
of course useful and can be supported. Still for a device driver (which
uses the virtual irq space) 0 should always be invalid.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |