[PATCH] regmap-i2c: Use i2c block command only if register value width is 8 bit

[PATCH] regmap-i2c: Use i2c block command only if register value width is 8 bit

[Guenter Roeck]

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.

Fixes: 29332534e2b6 ("regmap-i2c: Add smbus i2c block support")
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/base/regmap/regmap-i2c.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 1a8ec3b2b601..4735318f4268 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -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;
-- 
2.5.0

Applied "regmap-i2c: Use i2c block command only if register value width is 8 bit" to the regmap tree

[Mark Brown]

The patch

   regmap-i2c: Use i2c block command only if register value width is 8 bit

has been applied to the regmap tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From d4ef930638086aa40d14f245799cf7c56aaa91ff Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Tue, 21 Jun 2016 11:04:23 -0700
Subject: [PATCH] regmap-i2c: Use i2c block command only if register value
 width is 8 bit

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>
---
 drivers/base/regmap/regmap-i2c.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 1a8ec3b2b601..4735318f4268 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -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;
-- 
2.8.1