From: Mark Brown <broonie@kernel.org>
Date: Wed, 12 Jul 2023 12:16:40 +0100
Subject: [PATCH] regmap: Account for register length in SMBus I/O limits
References: bsc#1012628
Patch-mainline: 6.4.7
Git-commit: 0c9d2eb5e94792fe64019008a04d4df5e57625af
commit 0c9d2eb5e94792fe64019008a04d4df5e57625af upstream.
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@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20230712-regmap-max-transfer-v1-2-80e2aed22e83@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/base/regmap/regmap-i2c.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 980e5ce6..3ec611dc 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -242,8 +242,8 @@ static int regmap_i2c_smbus_i2c_read(void *context, const void *reg,
static const 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,
@@ -299,8 +299,8 @@ 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,
--
2.35.3