On Monday 20 July 2015 18:26:27, Mark Brown wrote:
> > AFAICS even a flat cache seems also only be usefull when providing
> > defaults, no? (Or having volatile registers).
>
> Well, it's *better* to provide defaults since otherwise everything
> defaults to 0 but it does avoid the whole allocation during fast path
> issue since it allocates the cache on init and perhaps that's OK.
There is another reason for using REGCACHE_FLAT: Using regcache_cache_only
(e.g. during suspend) which is not possible with REGCACHE_NONE.
> > So how to handle this properly? Bail out, if fast_io is available and
> > cache_type != (REGCACHE_NONE || REGCACHE_FLAT)?
>
> Or perhaps just if we have to do an allocation? I can see that someone
> might want to use an rbtree and would be careful enough to do the init,
> though I *am* a bit dubious about it.
I'm feeling uncomfortable this warning occured only when (at least)
CONFIG_LOCKDEP is enabled. It warns right ahead but only if you begged for
it...
Even if defaults are provided an extension to the register set (e.g. a more
recent IP revision with more features) might not be synchronized with the
defaults. Nobody might noticed until CONFIG_LOCKDEP is enabled and the
register without defaults gets written.
Best regards,
Alexander
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