Spurious interrupts on BCM2836?

[popcorn mix]

On Mon, Oct 24, 2016 at 6:37 PM, Eric Anholt <eric at anholt.net> wrote:
> I haven't seen it for a long time.  It's also not clear to me why a dsb
> there would do anything useful.

My understanding is that the ISR can be returned from before the
mailbox interrupt has been cleared -
the "writel(1 << ipi, mailbox0);" is still in flight.

That means we vector back into the ISR (interrupts are level
sensitive) immediately but find there is nothing to do.