This is a note to let you know that I've just added the patch titled
regmap: Account for register length in SMBus I/O limits
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
regmap-account-for-register-length-in-smbus-i-o-limi.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d846c197ed0eeb1a2ce67b20e7b34fb0aa8e5142
Author: Mark Brown <broonie@xxxxxxxxxx>
Date: Wed Jul 12 12:16:40 2023 +0100
regmap: Account for register length in SMBus I/O limits
[ Upstream commit 0c9d2eb5e94792fe64019008a04d4df5e57625af ]
The SMBus I2C buses have limits on the size of transfers they can do but
do not factor in the register length meaning we may try to do a transfer
longer than our length limit, the core will not take care of this.
Future changes will factor this out into the core but there are a number
of users that assume current behaviour so let's just do something
conservative here.
This does not take account padding bits but practically speaking these
are very rarely if ever used on I2C buses given that they generally run
slowly enough to mean there's no issue.
Cc: stable@xxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Reviewed-by: Xu Yilun <yilun.xu@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230712-regmap-max-transfer-v1-2-80e2aed22e83@xxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 052170ca0255e..b707913233c9b 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -246,8 +246,8 @@ static int regmap_i2c_smbus_i2c_read(void *context, const void *reg,
static struct regmap_bus regmap_i2c_smbus_i2c_block = {
.write = regmap_i2c_smbus_i2c_write,
.read = regmap_i2c_smbus_i2c_read,
- .max_raw_read = I2C_SMBUS_BLOCK_MAX,
- .max_raw_write = I2C_SMBUS_BLOCK_MAX,
+ .max_raw_read = I2C_SMBUS_BLOCK_MAX - 1,
+ .max_raw_write = I2C_SMBUS_BLOCK_MAX - 1,
};
static int regmap_i2c_smbus_i2c_write_reg16(void *context, const void *data,
@@ -303,8 +303,8 @@ static int regmap_i2c_smbus_i2c_read_reg16(void *context, const void *reg,
static const struct regmap_bus regmap_i2c_smbus_i2c_block_reg16 = {
.write = regmap_i2c_smbus_i2c_write_reg16,
.read = regmap_i2c_smbus_i2c_read_reg16,
- .max_raw_read = I2C_SMBUS_BLOCK_MAX,
- .max_raw_write = I2C_SMBUS_BLOCK_MAX,
+ .max_raw_read = I2C_SMBUS_BLOCK_MAX - 2,
+ .max_raw_write = I2C_SMBUS_BLOCK_MAX - 2,
};
static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
