USB: cdc-acm: fix runtime PM for control messages

commit bae3f4c53585e9a170da9436e0f06919874bda9a upstream.

Fix runtime PM handling of control messages by adding the required PM
counter operations.

Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

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

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index ea4fb1a..ed988ef 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -72,13 +72,23 @@ static const struct tty_port_operations acm_port_ops = {
 static int acm_ctrl_msg(struct acm *acm, int request, int value,
                                                        void *buf, int len)
 {
-       int retval = usb_control_msg(acm->dev, usb_sndctrlpipe(acm->dev, 0),
+       int retval;
+
+       retval = usb_autopm_get_interface(acm->control);
+       if (retval)
+               return retval;
+
+       retval = usb_control_msg(acm->dev, usb_sndctrlpipe(acm->dev, 0),
                request, USB_RT_ACM, value,
                acm->control->altsetting[0].desc.bInterfaceNumber,
                buf, len, 5000);
+
        dev_dbg(&acm->control->dev,
                        "%s - rq 0x%02x, val %#x, len %#x, result %d\n",
                        __func__, request, value, len, retval);
+
+       usb_autopm_put_interface(acm->control);
+
        return retval < 0 ? retval : 0;
 }