i2c: octeon: Missing AAK flag in case of I2C_M_RECV_LEN

BugLink: https://bugs.launchpad.net/bugs/1688132

During receive the controller requires the AAK flag for all
bytes but the final one. This was wrong in case of I2C_M_RECV_LEN,
where the decision if the final byte is to be transmitted
happened before adding the additional received length byte.

Set the AAK flag if additional bytes are to be received.
Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
(cherry picked from commit 908cf12b)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/i2c/busses/i2c-octeon.c

@@ -934,8 +934,15 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 		return result;
 
 	for (i = 0; i < length; i++) {
-		/* for the last byte TWSI_CTL_AAK must not be set */
-		if (i + 1 == length)
+		/*
+		 * For the last byte to receive TWSI_CTL_AAK must not be set.
+		 *
+		 * A special case is I2C_M_RECV_LEN where we don't know the
+		 * additional length yet. If recv_len is set we assume we're
+		 * not reading the final byte and therefore need to set
+		 * TWSI_CTL_AAK.
+		 */
+		if ((i + 1 == length) && !(recv_len && i == 0))
 			final_read = true;
 
 		/* clear iflg to allow next event */