Still more changes to try to prevent TX lockups. Will wait for one more

night of testing before merging to -stable.

Also added to code to detect TX underruns and automatically increase the
TX threshold to avoid them. Carefully placed diagnostig printf() about
this under #ifdef DIAGNOSTIC to avoid getting any panicky e-mails from
confused users, like I always do with the xl and dc drivers.

2 files changed, 48 insertions, 7 deletions

diff --git a/sys/dev/sf/if_sf.c b/sys/dev/sf/if_sf.c
index 69f5bc1..8f5fec3 100644
--- a/sys/dev/sf/if_sf.c
+++ b/sys/dev/sf/if_sf.c
@@ -170,6 +170,7 @@ static void sf_miibus_statchg	__P((device_t));
 
 static u_int32_t csr_read_4	__P((struct sf_softc *, int));
 static void csr_write_4		__P((struct sf_softc *, int, u_int32_t));
+static void sf_txthresh_adjust	__P((struct sf_softc *));
 
 #ifdef SF_USEIOSPACE
 #define SF_RES			SYS_RES_IOPORT
@@ -1039,18 +1040,22 @@ static void sf_txeof(sc)
 	while (cmpconsidx != cmpprodidx) {
 		cur_cmp = &sc->sf_ldata->sf_tx_clist[cmpconsidx];
 		cur_tx = &sc->sf_ldata->sf_tx_dlist[cur_cmp->sf_index >> 7];
-		SF_INC(cmpconsidx, SF_TX_CLIST_CNT);
 
 		if (cur_cmp->sf_txstat & SF_TXSTAT_TX_OK)
 			ifp->if_opackets++;
-		else
+		else {
+			if (cur_cmp->sf_txstat & SF_TXSTAT_TX_UNDERRUN)
+				sf_txthresh_adjust(sc);
 			ifp->if_oerrors++;
+		}
 
 		sc->sf_tx_cnt--;
 		if (cur_tx->sf_mbuf != NULL) {
 			m_freem(cur_tx->sf_mbuf);
 			cur_tx->sf_mbuf = NULL;
-		}
+		} else
+			break;
+		SF_INC(cmpconsidx, SF_TX_CLIST_CNT);
 	}
 
 	ifp->if_timer = 0;
@@ -1063,6 +1068,29 @@ static void sf_txeof(sc)
 	return;
 }
 
+static void sf_txthresh_adjust(sc)
+	struct sf_softc		*sc;
+{
+	u_int32_t		txfctl;
+	u_int8_t		txthresh;
+
+	txfctl = csr_read_4(sc, SF_TX_FRAMCTL);
+	txthresh = txfctl & SF_TXFRMCTL_TXTHRESH;
+	if (txthresh < 0xFF) {
+		txthresh++;
+		txfctl &= ~SF_TXFRMCTL_TXTHRESH;
+		txfctl |= txthresh;
+#ifdef DIAGNOSTIC
+		printf("sf%d: tx underrun, increasing "
+		    "tx threshold to %d bytes\n",
+		    sc->sf_unit, txthresh * 4);
+#endif
+		csr_write_4(sc, SF_TX_FRAMCTL, txfctl);
+	}
+
+	return;
+}
+
 static void sf_intr(arg)
 	void			*arg;
 {
@@ -1096,10 +1124,12 @@ static void sf_intr(arg)
 
 		if (status & SF_ISR_TX_TXDONE ||
 		    status & SF_ISR_TX_DMADONE ||
-		    status & SF_ISR_TX_QUEUEDONE ||
-		    status & SF_ISR_TX_LOFIFO)
+		    status & SF_ISR_TX_QUEUEDONE)
 			sf_txeof(sc);
 
+		if (status & SF_ISR_TX_LOFIFO)
+			sf_txthresh_adjust(sc);
+
 		if (status & SF_ISR_ABNORMALINTR) {
 			if (status & SF_ISR_STATSOFLOW) {
 				untimeout(sf_stats_update, sc,
@@ -1318,11 +1348,21 @@ static void sf_start(ifp)
 		return;
 	}
 
+	if (sc->sf_tx_cnt)
+		sf_txeof(sc);
+
 	txprod = csr_read_4(sc, SF_TXDQ_PRODIDX);
 	i = SF_IDX_HI(txprod) >> 4;
 
+	if (sc->sf_ldata->sf_tx_dlist[i].sf_mbuf != NULL) {
+		printf("sf%d: TX ring full, resetting\n", sc->sf_unit);
+		sf_init(sc);
+		txprod = csr_read_4(sc, SF_TXDQ_PRODIDX);
+		i = SF_IDX_HI(txprod) >> 4;
+	}
+
 	while(sc->sf_ldata->sf_tx_dlist[i].sf_mbuf == NULL) {
-		if (sc->sf_tx_cnt == (SF_TX_DLIST_CNT - 2)) {
+		if (sc->sf_tx_cnt >= (SF_TX_DLIST_CNT - 5)) {
 			ifp->if_flags |= IFF_OACTIVE;
 			cur_tx = NULL;
 			break;
diff --git a/sys/dev/sf/if_sfreg.h b/sys/dev/sf/if_sfreg.h
index fd2107f..1975cfc 100644
--- a/sys/dev/sf/if_sfreg.h
+++ b/sys/dev/sf/if_sfreg.h
@@ -349,7 +349,8 @@
 	(SF_IMR_RXDQ2_NOBUFS|SF_IMR_RXDQ1_DMADONE|SF_IMR_RXDQ2_DMADONE|	\
 	 SF_IMR_TX_TXDONE|SF_IMR_RXDQ1_NOBUFS|SF_IMR_RXDQ2_DMADONE|	\
 	 SF_IMR_NORMALINTR|SF_IMR_ABNORMALINTR|SF_IMR_TXCQ_NOBUFS|	\
-	 SF_IMR_RXCQ1_NOBUFS|SF_IMR_RXCQ2_NOBUFS|SF_IMR_STATSOFLOW)
+	 SF_IMR_RXCQ1_NOBUFS|SF_IMR_RXCQ2_NOBUFS|SF_IMR_STATSOFLOW|	\
+	 SF_IMR_TX_LOFIFO)
 
 /* TX descriptor queue control registers */
 #define SF_TXDQCTL_DESCTYPE	0x00000007