USB: pl2303: only wake up MSR queue on changes

Only wake up MSR wait queue on actual modem-status changes.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 11de1f1..64f093f 100644 (file)
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -118,6 +118,7 @@ MODULE_DEVICE_TABLE(usb, id_table);
 #define VENDOR_READ_REQUEST            0x01
 
 #define UART_STATE_INDEX               8
+#define UART_STATE_MSR_MASK            0x8b
 #define UART_STATE_TRANSIENT_MASK      0x74
 #define UART_DCD                       0x01
 #define UART_DSR                       0x02
@@ -828,15 +829,17 @@ static void pl2303_update_line_status(struct usb_serial_port *port,
        if (status & UART_BREAK_ERROR)
                usb_serial_handle_break(port);
 
-       wake_up_interruptible(&port->port.delta_msr_wait);
-
-       if (delta & UART_DCD) {
-               tty = tty_port_tty_get(&port->port);
-               if (tty) {
-                       usb_serial_handle_dcd_change(port, tty,
+       if (delta & UART_STATE_MSR_MASK) {
+               if (delta & UART_DCD) {
+                       tty = tty_port_tty_get(&port->port);
+                       if (tty) {
+                               usb_serial_handle_dcd_change(port, tty,
                                                        status & UART_DCD);
-                       tty_kref_put(tty);
+                               tty_kref_put(tty);
+                       }
                }
+
+               wake_up_interruptible(&port->port.delta_msr_wait);
        }
 }