USB: cypress_m8: 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, 4 insertions, 1 deletions

diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index 558605d646f3..07e003398613 100644
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -1187,7 +1187,10 @@ static void cypress_read_int_callback(struct urb *urb)
         if (priv->current_status != priv->prev_status) {
                 priv->diff_status |= priv->current_status ^
                         priv->prev_status;
-                wake_up_interruptible(&port->port.delta_msr_wait);
+
+                if (priv->diff_status & UART_MSR_MASK)
+                        wake_up_interruptible(&port->port.delta_msr_wait);
+
                 priv->prev_status = priv->current_status;
         }
         spin_unlock_irqrestore(&priv->lock, flags);