tty: serial: 8250_core: restore the LCR register in set_sleep

In ST16650V2 based serial uarts, while initalizing the PM state,
LCR registers are being initialized to 0 in serial8250_set_sleep().
If console port is already initialized and being used, this will
throws garbage in the console.

Signed-off-by: Sudhir Sreedharan <ssreedharan@mvista.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index ca5cfdc1459a61ca407f9888cbe20d50e33b71b3..b1704875694123734c6e52404538eca53eb3afa9 100644 (file)
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -595,6 +595,7 @@ static void serial8250_rpm_put_tx(struct uart_8250_port *p)
  */
 static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
 {
+       unsigned char lcr = 0, efr = 0;
        /*
         * Exar UARTs have a SLEEP register that enables or disables
         * each UART to enter sleep mode separately.  On the XR17V35x the
@@ -611,6 +612,8 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
 
        if (p->capabilities & UART_CAP_SLEEP) {
                if (p->capabilities & UART_CAP_EFR) {
+                       lcr = serial_in(p, UART_LCR);
+                       efr = serial_in(p, UART_EFR);
                        serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B);
                        serial_out(p, UART_EFR, UART_EFR_ECB);
                        serial_out(p, UART_LCR, 0);
@@ -618,8 +621,8 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
                serial_out(p, UART_IER, sleep ? UART_IERX_SLEEP : 0);
                if (p->capabilities & UART_CAP_EFR) {
                        serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B);
-                       serial_out(p, UART_EFR, 0);
-                       serial_out(p, UART_LCR, 0);
+                       serial_out(p, UART_EFR, efr);
+                       serial_out(p, UART_LCR, lcr);
                }
        }
 out: