On Thu, Oct 29, 2020 at 02:15:10PM +0000, Robin Murphy wrote:

> Or maybe the regmap API itself deserves extending with a "deferred"
> operating mode where updates to the cached state can be separated from
> committing that state to the underlying hardware.

> ...which, after a brief code search out of curiosity, apparently already
> exists in the form of regcache_cache_only()/regcache_sync(), so there's
> probably no need to reinvent it :)

Yes, exactly.  One of the big use cases for regmap on MMIO devices is
being able to access the register map without the hardware being there,
this would be another application of the cache stuff.