serial: Fix send_xchar() handlers
START_CHAR() & STOP_CHAR() can be disabled if set to '\0'
(__DISABLED_CHAR). UART drivers which define a send_xchar()
handler must not transmit __DISABLED_CHAR.
Document requirement.
Affected drivers:
sunsab
sunhv
cc: David S. Miller <davem@davemloft.net>
cc: <sparclinux@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
index b9598b2..0af75f8 100644
--- a/drivers/tty/serial/sunsab.c
+++ b/drivers/tty/serial/sunsab.c
@@ -468,6 +468,9 @@
struct uart_sunsab_port *up = (struct uart_sunsab_port *) port;
unsigned long flags;
+ if (ch == __DISABLED_CHAR)
+ return;
+
spin_lock_irqsave(&up->port.lock, flags);
sunsab_tec_wait(up);