Re: [PATCH 6/6 v3] regmap: Incorporate the regcache core into regmap

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

On Thu, Sep 15, 2011 at 05:19:32PM +0200, Lars-Peter Clausen wrote:

> > +	if (!map->cache_bypass) {
> > +		ret = regcache_write(map, reg, val);
> > +		if (ret < 0) {
> > +			mutex_unlock(&map->lock);
> > +			return ret;
> > +		}
> > +		if (map->cache_only) {
> > +			mutex_unlock(&map->lock);
> > +			return 0;
> > +		}
> > +	}

> Would it make sense to move this into _regmap_write ? In that case the code
> wouldn't have to be duplicated in regmap_update_bits and as a bonus it wouldn't
> have to deal with the mutex either.

That does seem sensible, yes.

> > +	if (!map->cache_bypass) {
> > +		ret = regcache_read(map, reg, val);
> > +		if (!ret) {
> > +			mutex_unlock(&map->lock);
> > +			return 0;
> > +		}

> So in case regmap_readable is not true for this register regcache_read will
> return -EIO and we'll fallback to an uncached read. This doesn't make sense in
> my opinion. Or what are the except semantics regmap_readable supposed to be?

It's a bit interesting but falling back to asking the hardware is
probably the right thing to do for cases where you're doing things like
using unspecified registers to activate undocumented features - the
register isn't really documented as being there and may do odd things
but if the device manufacturer gives you an approved sequence then you
can probably use it safely.