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regmap-i2c: Use i2c block command only if register value width is 8 bit
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Chips with 16-bit registers don't usually work well with I2C block
commands. For example, neither the LM75 datasheet nor the TMP102 datasheet
mentions block command support, and in fact it does not work for any of
those chips. Also, it is not clear how the block command would handle
16-bit SMBus operations in the fist place, since the data format associated
with those commands is either little endian or big endian, which requires
some kind of conversion to or from host byte order.

Only use i2c block commands if both register and value width is 8 bit.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
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Guenter Roeck authored and Mark Brown committed Jun 22, 2016
1 parent 1a695a9 commit d4ef930
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion drivers/base/regmap/regmap-i2c.c
Original file line number Diff line number Diff line change
@@ -259,7 +259,7 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
{
if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
return &regmap_i2c;
else if (config->reg_bits == 8 &&
else if (config->val_bits == 8 && config->reg_bits == 8 &&
i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_I2C_BLOCK))
return &regmap_i2c_smbus_i2c_block;

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