[PATCH] arm: dts: exynos5: Remove multi core timer

[Chirantan Ekbote]

>>> Anyway, I'm by no means opposed to switching to arch timers. They
>>> provide a well designed, generic interface and drivers shared by
>>> multiple platforms, which means more code sharing and possibly more eyes
>>> looking at the code, which is always good. However if they don't support
>>> low power states correctly, we can't just remove MCT.
>>
>> I think low power states aren't in mainline (right?).
>>
>> One solution that might work could be to leave the device tree entry
>> alone but change the MCT init code to simply act as a no-op if it sees
>> an arch timer is in the device tree and enabled.  Then when/if someone
>> got the low power states enabled we could just change source code
>> rather than dts files.
>>

Doug and I were talking about this and we think we may have a way to
have the mct and arch timers co-exist.  The main issue is that the mct
(and therefore arch timer) gets cleared once during boot and every
time we do a suspend / resume.  This happens in
exynos4_mct_frc_start() but it's not immediately clear to us why the
counter needs to be reset at all.  If we remove the lines that clear
the counter then there is no longer an issue with having both the mct
and the arch timers on at the same time.

Alternately, if there is some code that depends on the mct being reset
we could store an offset instead of clearing the counter and then
subtract that offset every time something reads it.  Doug has a patch
that does this at
https://chromium-review.googlesource.com/#/c/200298/.  Effectively the
visible behavior will not change.  Would either of these options work?

Chirantan