gigaset: fix reject/hangup handling

Signal D channel disconnect in a few cases where it was missed,
including when an incoming call is disconnected before it was
accepted.

Impact: error handling improvement
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/gigaset/ev-layer.c

@@ -707,6 +707,11 @@ static void disconnect(struct at_state_t **at_state_p)
 	if (bcs) {
 		/* B channel assigned: invoke hardware specific handler */
 		cs->ops->close_bchannel(bcs);
+		/* notify LL */
+		if (bcs->chstate & (CHS_D_UP | CHS_NOTIFY_LL)) {
+			bcs->chstate &= ~(CHS_D_UP | CHS_NOTIFY_LL);
+			gigaset_i4l_channel_cmd(bcs, ISDN_STAT_DHUP);
+		}
 	} else {
 		/* no B channel assigned: just deallocate */
 		spin_lock_irqsave(&cs->lock, flags);