sunsab: Fix detection of BREAK on sunsab serial console

[ Upstream commit fe418231 ]

Fix detection of BREAK on sunsab serial console: BREAK detection was only
performed when there were also serial characters received simultaneously.
To handle all BREAKs correctly, the check for BREAK and the corresponding
call to uart_handle_break() must also be done if count == 0, therefore
duplicate this code fragment and pull it out of the loop over the received
characters.

Patch applies to 3.16-rc6.
Signed-off-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/tty/serial/sunsab.c

@@ -156,6 +156,15 @@ receive_chars(struct uart_sunsab_port *up,
 	    (up->port.line == up->port.cons->index))
 		saw_console_brk = 1;
 
+	if (count == 0) {
+		if (unlikely(stat->sreg.isr1 & SAB82532_ISR1_BRK)) {
+			stat->sreg.isr0 &= ~(SAB82532_ISR0_PERR |
+					     SAB82532_ISR0_FERR);
+			up->port.icount.brk++;
+			uart_handle_break(&up->port);
+		}
+	}
+
 	for (i = 0; i < count; i++) {
 		unsigned char ch = buf[i], flag;