if_awg: drain tx buffers and clear rx buffers when stopping

Stale packets should not be transmitted when the interface comes up after being down.
Count the successfully transmitted ones for statistics and drop the rest.

Submitted by:	Guy Yur <guyyur@gmail.com>
Differential Revision:	https://reviews.freebsd.org/D12539

1 files changed, 36 insertions, 0 deletions

diff --git a/sys/arm/allwinner/if_awg.c b/sys/arm/allwinner/if_awg.c
index 64085703583a..81aca029082f 100644
--- a/sys/arm/allwinner/if_awg.c
+++ b/sys/arm/allwinner/if_awg.c
@@ -215,6 +215,8 @@ static struct resource_spec awg_spec[] = {
 	{ -1, 0 }
 };
 
+static void awg_txeof(struct awg_softc *sc);
+
 static int
 awg_miibus_readreg(device_t dev, int phy, int reg)
 {
@@ -809,6 +811,7 @@ awg_stop(struct awg_softc *sc)
 {
 	if_t ifp;
 	uint32_t val;
+	int i;
 
 	AWG_ASSERT_LOCKED(sc);
 
@@ -843,6 +846,39 @@ awg_stop(struct awg_softc *sc)
 
 	sc->link = 0;
 
+	/* Finish handling transmitted buffers */
+	awg_txeof(sc);
+
+	/* Release any untransmitted buffers. */
+	for (i = sc->tx.next; sc->tx.queued > 0; i = TX_NEXT(i)) {
+		val = le32toh(sc->tx.desc_ring[i].status);
+		if ((val & TX_DESC_CTL) != 0)
+			break;
+		awg_clean_txbuf(sc, i);
+	}
+	sc->tx.next = i;
+	for (; sc->tx.queued > 0; i = TX_NEXT(i)) {
+		sc->tx.desc_ring[i].status = 0;
+		awg_clean_txbuf(sc, i);
+	}
+	sc->tx.cur = sc->tx.next;
+	bus_dmamap_sync(sc->tx.desc_tag, sc->tx.desc_map,
+	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
+
+	/* Setup RX buffers for reuse */
+	bus_dmamap_sync(sc->rx.desc_tag, sc->rx.desc_map,
+	    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
+
+	for (i = sc->rx.cur; ; i = RX_NEXT(i)) {
+		val = le32toh(sc->rx.desc_ring[i].status);
+		if ((val & RX_DESC_CTL) != 0)
+			break;
+		awg_reuse_rxdesc(sc, i);
+	}
+	sc->rx.cur = i;
+	bus_dmamap_sync(sc->rx.desc_tag, sc->rx.desc_map,
+	    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
+
 	if_setdrvflagbits(ifp, 0, IFF_DRV_RUNNING | IFF_DRV_OACTIVE);
 }