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>
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@ -583,18 +583,19 @@ int regmap_update_bits(struct regmap *map, unsigned int reg,
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unsigned int mask, unsigned int val)
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{
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int ret;
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unsigned int tmp;
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unsigned int tmp, orig;
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mutex_lock(&map->lock);
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ret = _regmap_read(map, reg, &tmp);
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ret = _regmap_read(map, reg, &orig);
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if (ret != 0)
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goto out;
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tmp &= ~mask;
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tmp = orig & ~mask;
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tmp |= val & mask;
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ret = _regmap_write(map, reg, tmp);
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if (tmp != orig)
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ret = _regmap_write(map, reg, tmp);
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out:
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mutex_unlock(&map->lock);
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