[PATCH 08/15] powerpc/powernv: implement opal_put_chars_atomic

[Michael Ellerman]

Nicholas Piggin <npiggin at gmail.com> writes:

> On Tue, 01 May 2018 19:48:58 +1000
> Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
>
>> On Tue, 2018-05-01 at 00:55 +1000, Nicholas Piggin wrote:
>> > The RAW console does not need writes to be atomic, so relax
>> > opal_put_chars to be able to do partial writes, and implement an
>> > _atomic variant which does not take a spinlock. This API is used
>> > in xmon, so the less locking that is used, the better chance there
>> > is that a crash can be debugged.  
>> 
>> Same comment I already had :-) "atomic" in Linux tends to mean
>> something else (ie, atomic context), so I'd rather have something
>> like opal_put_chars_sync() or such...
>
> Oh yeah, I didn't ignore you, just... I thought atomic was okay.
> atomic *also* tends to mean happens atomically. I think the in
> atomic context meaning actually tends to be inatomic.
>
> Sync I actually thought could be more easily confused with
> synchronous vs asynchronous here.

I think we probably want opal_put_chars() to stay as it is.

And then add a variant for the call (just xmon?) that want lock free
behaviour.

opal_put_chars_unlocked() or something?

cheers