On Tue, 2017-03-28 at 09:32 +0100, Marc Zyngier wrote:

I'm a bit concerned by this. It means that you can't even mask an
interrupt. Is that really what you intend to do? Or all that the HW can
do? If you cannot mask an interrupt, you're at the mercy of a screaming
device...

This is not really an interrupt controller. It's a "summary" register
that reflects the state of the 14 i2c controller interrupts.

This approach does have the advantage of providing separate counters in
/proc/interrupts which is rather nice, but it does have overhead. On
those shittly little ARMv9 400Mhz cores it can be significant.

I would personally have some kind of trick to register a single
interrupt handler that calls directly the handlers of the respective
i2c busses via a simple indirection for speed, maybe adding my custom
sysfs or debugfs statistics. But that's just me trying to suck the last
cycle out of the bloody thing ;-)

Cheers,
Ben.