USB: ftdi_sio: clean up line-status handling

Reverse priority of errors reported to ldisc so that it matches that of
other serial drivers (break takes precedence over parity, which takes
precedence over framing errors).

Also make sure overrun errors are handled as in other drivers, that is,
an overrun error is always reported and is not associated with any
received character (instead a NULL character with the TTY_OVERRUN flag
set is inserted).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/ftdi_sio.c

@@ -1767,6 +1767,8 @@ static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
 	return count;
 }
 
+#define FTDI_RS_ERR_MASK (FTDI_RS_BI | FTDI_RS_PE | FTDI_RS_FE | FTDI_RS_OE)
+
 static int ftdi_process_packet(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ftdi_private *priv,
 		char *packet, int len)
@@ -1793,28 +1795,21 @@ static int ftdi_process_packet(struct tty_struct *tty,
 		priv->prev_status = status;
 	}
 
-	/*
-	 * Although the device uses a bitmask and hence can have multiple
-	 * errors on a packet - the order here sets the priority the error is
-	 * returned to the tty layer.
-	 */
 	flag = TTY_NORMAL;
-	if (packet[1] & FTDI_RS_OE) {
-		flag = TTY_OVERRUN;
-		dbg("OVERRRUN error");
-	}
-	if (packet[1] & FTDI_RS_BI) {
-		flag = TTY_BREAK;
-		dbg("BREAK received");
-		usb_serial_handle_break(port);
-	}
-	if (packet[1] & FTDI_RS_PE) {
-		flag = TTY_PARITY;
-		dbg("PARITY error");
-	}
-	if (packet[1] & FTDI_RS_FE) {
-		flag = TTY_FRAME;
-		dbg("FRAMING error");
+	if (packet[1] & FTDI_RS_ERR_MASK) {
+		/* Break takes precedence over parity, which takes precedence
+		 * over framing errors */
+		if (packet[1] & FTDI_RS_BI) {
+			flag = TTY_BREAK;
+			usb_serial_handle_break(port);
+		} else if (packet[1] & FTDI_RS_PE) {
+			flag = TTY_PARITY;
+		} else if (packet[1] & FTDI_RS_FE) {
+			flag = TTY_FRAME;
+		}
+		/* Overrun is special, not associated with a char */
+		if (packet[1] & FTDI_RS_OE)
+			tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 	}
 
 	len -= 2;