Mark,

On Fri, 26 Feb 2016 12:09:49 +0900, Mark Brown wrote:

also caused by b4f596b19624 (arm64: add mvebu architecture entry) which
enables MVBEU on arm64, the commit was present for a little while and
the error cropped up but didn't get reported due to other things masking
it.  atomic_io_modify() is only available on ARM, I'm unsure if this
needs a driver change or if the driver is just specific to older
hardware anyway.  The code is only used in the init path accessing what
look to be device specific registers so I'm not 100% clear why it
specifically needs to be an atomic modify.

atomic_io_modify() is also used in the ->start() and ->stop() hooks, so
not only during initialization. The reason we use atomic_io_modify()
here is because this TIMER_CTRL register is shared with the clocksource
drivers (time-orion.c, time-armada-370-xp.c). Indeed, the timers and
watchdogs share a single register that allows to enable/disable all
timers/watchdogs. Somewhat unfortunate choice, but that's how the HW is.

By far the easiest solution is to add "depends on ARM" to
ORION_WATCHDOG.

Another solution would be to provide an implementation of
atomic_io_modify() on arm64, though that would need the ACK from the
ARM64 maintainers.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com