serial: 8250_fintek: Return -EINVAL on invalid configuration

Hardware does not support having the same RTS level during RX and TX when RS485 mode is on (URA in Fintek terminology). The manufacturer has also confirmed that the delays are not enabled if the RS485 mode is not enabled. Therefore we should return -EINVAL if the user wants to have the same value for RTS_ON_SEND and RTS_AFTER_SEND. Cc: "Ji-Ze Hong (Peter Hong)" <[email protected]> Cc: Lukas Wunner <[email protected]> Signed-off-by: Ricardo Ribalda Delgado <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
JerzyD72 · Nov 8, 2017 · 7ecc770 · 7ecc770
1 parent e5656d4
commit 7ecc770
Showing 1 changed file with 9 additions and 8 deletions.
diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c
@@ -197,10 +197,17 @@ static int fintek_8250_rs485_config(struct uart_port *port,
 	if (!pdata)
 		return -EINVAL;
 
-	if (rs485->flags & SER_RS485_ENABLED)
+	/* Hardware do not support same RTS level on send and receive */
+	if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
+			!(rs485->flags & SER_RS485_RTS_AFTER_SEND))
+		return -EINVAL;
+
+	if (rs485->flags & SER_RS485_ENABLED) {
 		memset(rs485->padding, 0, sizeof(rs485->padding));
-	else
+		config |= RS485_URA;
+	} else {
 		memset(rs485, 0, sizeof(*rs485));
+	}
 
 	rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND |
 			SER_RS485_RTS_AFTER_SEND;
@@ -215,12 +222,6 @@ static int fintek_8250_rs485_config(struct uart_port *port,
 		config |= RXW4C_IRA;
 	}
 
-	if ((!!(rs485->flags & SER_RS485_RTS_ON_SEND)) ==
-			(!!(rs485->flags & SER_RS485_RTS_AFTER_SEND)))
-		rs485->flags &= ~SER_RS485_ENABLED;
-	else
-		config |= RS485_URA;
-
 	if (rs485->flags & SER_RS485_RTS_ON_SEND)
 		config |= RTS_INVERT;