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    SubjectRe: [PATCH 5/7] regmap: Check if a register is writable instead of readable in regcache_read
    On 11/16/2011 05:16 PM, Mark Brown wrote:
    > On Wed, Nov 16, 2011 at 04:28:20PM +0100, Lars-Peter Clausen wrote:
    >> Currently regcache checks whether a register is readable when performing a
    >> cached read and returns an error if not. Change this check to test whether the
    >> register is writable. This makes more sense, since reading from the cache when
    >> the register is not readable allows the operation described above, but if the
    >> register is not writable there shouldn't be a value for it in the cache anyway.
    > This logic doesn't entirely follow - one can have registers which are
    > volatile but could be read once at startup. Plus...

    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

    >> @@ -206,7 +206,7 @@ int regcache_read(struct regmap *map,
    >> BUG_ON(!map->cache_ops);
    >> - if (!regmap_readable(map, reg))
    >> + if (!regmap_writeable(map, reg))
    >> return -EIO;
    > ...the code winds up just looking like an obvious bug.

    Why? If a register is not writable we won't have anything in the cache for
    it. So reading from the cache for a register which is not writable doesn't
    make any sense.

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      Last update: 2011-11-16 17:37    [W:0.020 / U:99.860 seconds]
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