i2c: npcm7xx: Fix callback completion ordering

[ Upstream commit 92e73d807b68b2214fcafca4e130b5300a9d4b3c ]

Sometimes, our completions race with new master transfers and override
the bus->operation and bus->master_or_slave variables. This causes
transactions to timeout and kernel crashes less frequently.

To remedy this, we re-order all completions to the very end of the
function.

Fixes: 56a1485 ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: William A. Kennington III <[email protected]>
Reviewed-by: Tali Perry <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

drivers/i2c/busses/i2c-npcm7xx.c

@@ -675,6 +675,7 @@ static void npcm_i2c_callback(struct npcm_i2c *bus,
 {
 	struct i2c_msg *msgs;
 	int msgs_num;
+	bool do_complete = false;
 
 	msgs = bus->msgs;
 	msgs_num = bus->msgs_num;
@@ -701,23 +702,17 @@ static void npcm_i2c_callback(struct npcm_i2c *bus,
 				 msgs[1].flags & I2C_M_RD)
 				msgs[1].len = info;
 		}
-		if (completion_done(&bus->cmd_complete) == false)
-			complete(&bus->cmd_complete);
-	break;
-
+		do_complete = true;
+		break;
 	case I2C_NACK_IND:
 		/* MASTER transmit got a NACK before tx all bytes */
 		bus->cmd_err = -ENXIO;
-		if (bus->master_or_slave == I2C_MASTER)
-			complete(&bus->cmd_complete);
-
+		do_complete = true;
 		break;
 	case I2C_BUS_ERR_IND:
 		/* Bus error */
 		bus->cmd_err = -EAGAIN;
-		if (bus->master_or_slave == I2C_MASTER)
-			complete(&bus->cmd_complete);
-
+		do_complete = true;
 		break;
 	case I2C_WAKE_UP_IND:
 		/* I2C wake up */
@@ -731,6 +726,8 @@ static void npcm_i2c_callback(struct npcm_i2c *bus,
 	if (bus->slave)
 		bus->master_or_slave = I2C_SLAVE;
 #endif
+	if (do_complete)
+		complete(&bus->cmd_complete);
 }
 
 static u8 npcm_i2c_fifo_usage(struct npcm_i2c *bus)