SERIAL: omap: fix set_mctrl() breakage

c538d20c7f (and maybe previous commits) broke set_mctrl() by making
it only capable of setting bits in the MCR register.  This prevents
software controlled flow control and modem control line manipulation
via TIOCMSET/TIOCMBIC from working correctly.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 6ef4cc4..fb06def 100644 (file)
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -504,7 +504,7 @@ static unsigned int serial_omap_get_mctrl(struct uart_port *port)
 static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
        struct uart_omap_port *up = to_uart_omap_port(port);
-       unsigned char mcr = 0;
+       unsigned char mcr = 0, old_mcr;
 
        dev_dbg(up->port.dev, "serial_omap_set_mctrl+%d\n", up->port.line);
        if (mctrl & TIOCM_RTS)
@@ -519,8 +519,10 @@ static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
                mcr |= UART_MCR_LOOP;
 
        pm_runtime_get_sync(up->dev);
-       up->mcr = serial_in(up, UART_MCR);
-       up->mcr |= mcr;
+       old_mcr = serial_in(up, UART_MCR);
+       old_mcr &= ~(UART_MCR_LOOP | UART_MCR_OUT2 | UART_MCR_OUT1 |
+                    UART_MCR_DTR | UART_MCR_RTS);
+       up->mcr = old_mcr | mcr;
        serial_out(up, UART_MCR, up->mcr);
        pm_runtime_mark_last_busy(up->dev);
        pm_runtime_put_autosuspend(up->dev);