USB: oti6858: 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, 5 insertions, 1 deletions

diff --git a/drivers/usb/serial/oti6858.c b/drivers/usb/serial/oti6858.c
index 1dea599bb71b..9ea15e0a22d8 100644
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -103,6 +103,7 @@ struct oti6858_control_pkt {
 #define TX_BUFFER_EMPTIED       0x09
         u8      pin_state;
 #define PIN_MASK                0x3f
+#define PIN_MSR_MASK            0x1b
 #define PIN_RTS                 0x20    /* output pin */
 #define PIN_CTS                 0x10    /* input pin, active low */
 #define PIN_DSR                 0x08    /* input pin, active low */
@@ -739,8 +740,11 @@ static void oti6858_read_int_callback(struct urb *urb)
                 }
 
                 if (!priv->transient) {
-                        if (xs->pin_state != priv->status.pin_state)
+                        u8 delta = xs->pin_state ^ priv->status.pin_state;
+
+                        if (delta & PIN_MSR_MASK)
                                 wake_up_interruptible(&port->port.delta_msr_wait);
+
                         memcpy(&priv->status, xs, OTI6858_CTRL_PKT_SIZE);
                 }