i2c: designware: Correct length byte validation logic

Commit 0daede8 ("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 f53f15b ("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 0daede8
("i2c: designware: Convert driver to using regmap API").

Fixes: f53f15b ("i2c: designware: Get right data length")
Fixes: 0daede8 ("i2c: designware: Convert driver to using regmap API")
Cc: [email protected]
Signed-off-by: Tam Nguyen <[email protected]>
Signed-off-by: Quan Nguyen <[email protected]>
Acked-by: Jarkko Nikula <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Andi Shyti <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Author: qnguyen-ampere

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

@@ -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;