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Subject[PATCH v2 1/2] hwmon: (ina3221) Do not read-back to cache reg_config
Date
Reading back the CONFIG register increases an extra I2C
transaction. This's not necessary and could be replaced
with a local variable caching the register settings.

So this patch replaces two readback regmap_read() calls
with a tmp variable.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
drivers/hwmon/ina3221.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index 74d39d212931..62040aac653c 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -309,21 +309,22 @@ static int ina3221_write_chip(struct device *dev, u32 attr, long val)
{
struct ina3221_data *ina = dev_get_drvdata(dev);
int ret, idx;
+ u32 tmp;

switch (attr) {
case hwmon_chip_samples:
idx = find_closest(val, ina3221_avg_samples,
ARRAY_SIZE(ina3221_avg_samples));

- ret = regmap_update_bits(ina->regmap, INA3221_CONFIG,
- INA3221_CONFIG_AVG_MASK,
- idx << INA3221_CONFIG_AVG_SHIFT);
+ tmp = (ina->reg_config & ~INA3221_CONFIG_AVG_MASK) |
+ (idx << INA3221_CONFIG_AVG_SHIFT);
+ ret = regmap_write(ina->regmap, INA3221_CONFIG, tmp);
if (ret)
return ret;

/* Update reg_config accordingly */
- return regmap_read(ina->regmap, INA3221_CONFIG,
- &ina->reg_config);
+ ina->reg_config = tmp;
+ return 0;
default:
return -EOPNOTSUPP;
}
@@ -359,6 +360,7 @@ static int ina3221_write_enable(struct device *dev, int channel, bool enable)
struct ina3221_data *ina = dev_get_drvdata(dev);
u16 config, mask = INA3221_CONFIG_CHx_EN(channel);
u16 config_old = ina->reg_config & mask;
+ u32 tmp;
int ret;

config = enable ? mask : 0;
@@ -377,14 +379,13 @@ static int ina3221_write_enable(struct device *dev, int channel, bool enable)
}

/* Enable or disable the channel */
- ret = regmap_update_bits(ina->regmap, INA3221_CONFIG, mask, config);
+ tmp = (ina->reg_config & ~mask) | (config & mask);
+ ret = regmap_write(ina->regmap, INA3221_CONFIG, tmp);
if (ret)
goto fail;

/* Cache the latest config register value */
- ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
- if (ret)
- goto fail;
+ ina->reg_config = tmp;

/* For disabling routine, decrease refcount or suspend() at last */
if (!enable)
--
2.17.1
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