Messages in this thread | | | Date | Wed, 16 Nov 2011 16:56:22 +0000 | From | Mark Brown <> | Subject | Re: [PATCH 5/7] regmap: Check if a register is writable instead of readable in regcache_read |
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On Wed, Nov 16, 2011 at 05:52:49PM +0100, Lars-Peter Clausen wrote: > On 11/16/2011 05:38 PM, Mark Brown wrote:
> >> Hm? The use case here is chips which do not support readback. So we never > >> want to fallback to a hardware read but still want to be able to do a cached > >> read.
> > This code will be run on every chip, including chips with read/write > > access. Caches are useful for all chips.
> Of course. And it still works for chips with read/write support with this > patch, but it doesn't work for chips without read support without this patch.
No, it'll fail if we ever cache volatile registers at startup (which is a perfectly sensible thing to do for things like chip revisions - they're not something we can hard code the default for but they're not going to change at runtime).
> > If you're looking at the read function and it's checking to see if the > > register is writeable the first thought would be that this is a > > cut'n'paste error. The above code is at best *way* too cute.
> We can of course add a comment explaining why it is regmap_writable instead > of regmap_readable.
No, really - just do something legible and robust. For example, teach regmap_readable() about the cache.
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