Regression with legacy IRQ numbers caused by 9a1091ef0017

[Tony Lindgren]

* Russell King - ARM Linux <linux at arm.linux.org.uk> [150116 08:33]:
> On Fri, Jan 16, 2015 at 08:21:20AM -0800, Tony Lindgren wrote:
> > * Russell King - ARM Linux <linux at arm.linux.org.uk> [150115 09:22]:
> > > On Thu, Jan 15, 2015 at 07:28:39AM -0800, Tony Lindgren wrote:
> > > > * Russell King - ARM Linux <linux at arm.linux.org.uk> [150115 02:53]:
> > > > > I don't think we've proven a link there.  While you're right that it
> > > > > causes the wrong interrupt to be claimed, I have two kernels here,
> > > > > both claim the same interrupt, one which is multi-platform and issues
> > > > > that strange warning, and one which targets only OMAP4 which doesn't.
> > > > > 
> > > > > There's something else going on which causes the bus errors which we
> > > > > haven't found.
> > > > 
> > > > I think it gets triggered if you enable PREEMPT.
> > > 
> > > That's something which we can try to prove... build running now with
> > > CONFIG_PREEMPT=y
> > 
> > Looks like you now have the omap_l3_noc error appear for sdp4430 in
> > your logs after enabling PREEMPT.
> > 
> > I guess that means case closed for this one?
> 
> I would still like to understand /why/ enabling preempt causes the error.
> Changing the preempt configuration really should not change what happens
> on the bus.  (Think about it.)  It's an indication that there is some
> other error present.

We have a wrong irq number caused by $subject. And the wrong irq
gets triggered before the dma hardware is configured during dma
init. And then we get the invalid access error from omap_l3_noc.

> Unfortunately, the OMAP hardware appears to make it impossible to
> determine what the access that caused the error was, so it looks like
> it's pretty much undebuggable.

Yeah would be nice to have more info from omap_l3_noc.

Regards,

Tony