Index: if_fec.c
===================================================================
RCS file: /cvs/src/sys/arch/armv7/imx/if_fec.c,v
retrieving revision 1.20
diff -u -p -r1.20 if_fec.c
--- if_fec.c	22 Jan 2017 10:17:37 -0000	1.20
+++ if_fec.c	31 May 2017 10:41:45 -0000
@@ -799,18 +799,20 @@ fec_start(struct ifnet *ifp)
 		return;
 
 	for (;;) {
-		m_head = ifq_deq_begin(&ifp->if_snd);
+		if (sc->tx_desc_base[sc->cur_tx].status & ENET_TXD_READY) {
+			ifq_set_oactive(&ifp->if_snd);
+			break;
+		}
+
+		m_head = ifq_dequeue(&ifp->if_snd);
 		if (m_head == NULL)
 			break;
 
 		if (fec_encap(sc, m_head)) {
-			ifq_deq_rollback(&ifp->if_snd, m_head);
-			ifq_set_oactive(&ifp->if_snd);
-			break;
+			m_freem(m_head);
+			continue;
 		}
 
-		ifq_deq_commit(&ifp->if_snd, m_head);
-
 #if NBPFILTER > 0
 		if (ifp->if_bpf)
 			bpf_mtap(ifp->if_bpf, m_head, BPF_DIRECTION_OUT);
@@ -823,18 +825,12 @@ fec_start(struct ifnet *ifp)
 int
 fec_encap(struct fec_softc *sc, struct mbuf *m)
 {
-	if (sc->tx_desc_base[sc->cur_tx].status & ENET_TXD_READY) {
-		printf("fec: tx queue full!\n");
+	if (m->m_pkthdr.len > ENET_MAX_PKT_SIZE)
 		return EIO;
-	}
-
-	if (m->m_pkthdr.len > ENET_MAX_PKT_SIZE) {
-		printf("fec: packet too big\n");
-		return EIO;
-	}
 
 	/* copy in the actual packet */
-	m_copydata(m, 0, m->m_pkthdr.len, (caddr_t)sc->tx_buffer_base[sc->cur_tx].data);
+	m_copydata(m, 0, m->m_pkthdr.len,
+	    (caddr_t)sc->tx_buffer_base[sc->cur_tx].data);
 
 	sc->tx_desc_base[sc->cur_tx].data_length = m->m_pkthdr.len;
 
@@ -908,10 +904,11 @@ fec_intr(void *arg)
 		if (ifp->if_flags & IFF_RUNNING)
 			fec_recv(sc);
 	}
-
-	/* Try to transmit. */
-	if (ifp->if_flags & IFF_RUNNING && !IFQ_IS_EMPTY(&ifp->if_snd))
-		fec_start(ifp);
+	if (ISSET(status, ENET_EIR_TXF)) {
+		/* Try to transmit. */
+		if (ifq_is_oactive(&ifp->if_snd))
+			ifq_restart(&ifp->if_snd);
+	}
 
 	return 1;
 }