Commit 49d4db39 authored Jul 26, 2023 by Quan Nguyen Committed by Wolfram Sang Aug 14, 2023

i2c: designware: Correct length byte validation logic



Commit 0daede80 ("i2c: designware: Convert driver to using regmap API")
changes the logic to validate the whole 32-bit return value of
DW_IC_DATA_CMD register instead of 8-bit LSB without reason.

Later, commit f53f15ba ("i2c: designware: Get right data length"),
introduced partial fix but not enough because the "tmp > 0" still test
tmp as 32-bit value and is wrong in case the IC_DATA_CMD[11] is set.

Revert the logic to just before commit 0daede80
("i2c: designware: Convert driver to using regmap API").

Fixes: f53f15ba ("i2c: designware: Get right data length")
Fixes: 0daede80 ("i2c: designware: Convert driver to using regmap API")
Cc: stable@vger.kernel.org
Signed-off-by: Tam Nguyen <tamnguyenchi@os.amperecomputing.com>
Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Link: https://lore.kernel.org/r/20230726080001.337353-2-tamnguyenchi@os.amperecomputing.com


Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

parent b610c4bb

drivers/i2c/busses/i2c-designware-master.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -588,9 +588,10 @@ i2c_dw_read(struct dw_i2c_dev *dev)
		u32 flags = msgs[dev->msg_read_idx].flags;

		regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
		tmp &= DW_IC_DATA_CMD_DAT;
		/* Ensure length byte is a valid value */
		if (flags & I2C_M_RECV_LEN &&
		(tmp & DW_IC_DATA_CMD_DAT) <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
		tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
		len = i2c_dw_recv_len(dev, tmp);
		}
		*buf++ = tmp;