diff options
| author | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2011-11-18 16:03:50 +0000 |
|---|---|---|
| committer | Lokesh Pathak <lpathak@nvidia.com> | 2012-03-05 07:53:44 -0800 |
| commit | 536869bd1abcaddf053e4f89ab1027a510b725fb (patch) | |
| tree | c3a3db4794781b3730396ef44c319115076f9641 /drivers/base/regmap/regmap.c | |
| parent | 532545df7bab481d517619c474f42d28f8129e08 (diff) | |
regmap: Suppress noop writes in regmap_update_bits()
If the new register value is identical to the original one then suppress
the write to the hardware in regmap_update_bits(), saving some I/O cost.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
(cherry picked from commit d91e8db2c3bbe8ef0e2f3e1a6ff5b31a8d53ef16)
Change-Id: Ia6c6e291371e6937b893501e763b7e589f700d93
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-on: http://git-master/r/87566
Diffstat (limited to 'drivers/base/regmap/regmap.c')
| -rw-r--r-- | drivers/base/regmap/regmap.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index 32af469f7440..7766d940d3c2 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -583,18 +583,19 @@ int regmap_update_bits(struct regmap *map, unsigned int reg, unsigned int mask, unsigned int val) { int ret; - unsigned int tmp; + unsigned int tmp, orig; mutex_lock(&map->lock); - ret = _regmap_read(map, reg, &tmp); + ret = _regmap_read(map, reg, &orig); if (ret != 0) goto out; - tmp &= ~mask; + tmp = orig & ~mask; tmp |= val & mask; - ret = _regmap_write(map, reg, tmp); + if (tmp != orig) + ret = _regmap_write(map, reg, tmp); out: mutex_unlock(&map->lock); |