From: Jim Wylder <jwylder@xxxxxxxxxx> [ Upstream commit 611b7eb19d0a305d4de00280e4a71a1b15c507fc ] Currently, when an adapter defines a max_write_len quirk, the data will be chunked into data sizes equal to the max_write_len quirk value. But the payload will be increased by the size of the register address before transmission. The resulting value always ends up larger than the limit set by the quirk. Avoid this error by setting regmap's max_write to the quirk's max_write_len minus the number of bytes for the register and padding. This allows the chunking to work correctly for this limited case without impacting other use-cases. Signed-off-by: Jim Wylder <jwylder@xxxxxxxxxx> Link: https://msgid.link/r/20240523211437.2839942-1-jwylder@xxxxxxxxxx Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/base/regmap/regmap-i2c.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c index 3ec611dc0c09f..a905e955bbfc7 100644 --- a/drivers/base/regmap/regmap-i2c.c +++ b/drivers/base/regmap/regmap-i2c.c @@ -350,7 +350,8 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c, if (quirks->max_write_len && (bus->max_raw_write == 0 || bus->max_raw_write > quirks->max_write_len)) - max_write = quirks->max_write_len; + max_write = quirks->max_write_len - + (config->reg_bits + config->pad_bits) / BITS_PER_BYTE; if (max_read || max_write) { ret_bus = kmemdup(bus, sizeof(*bus), GFP_KERNEL); -- 2.43.0
