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>

1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 11de1f169308..64f093f16981 100644
--- 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);
         }
 }