Add workaround for BCM5906 controller silicon bug. If device

receive two back-to-back send BDs with less than or equal to 8
total bytes then the device may hang. The two back-to-back send
BDs must be in the same frame for this failure to occur.
Thanks to davidch for detailed errata information.

Reviewed by:	davidch

2 files changed, 44 insertions, 0 deletions

diff --git a/sys/dev/bge/if_bge.c b/sys/dev/bge/if_bge.c
index 662713f..5380931 100644
--- a/sys/dev/bge/if_bge.c
+++ b/sys/dev/bge/if_bge.c
@@ -374,6 +374,7 @@ static void bge_tick(void *);
 static void bge_stats_clear_regs(struct bge_softc *);
 static void bge_stats_update(struct bge_softc *);
 static void bge_stats_update_regs(struct bge_softc *);
+static struct mbuf *bge_check_short_dma(struct mbuf *);
 static struct mbuf *bge_setup_tso(struct bge_softc *, struct mbuf *,
     uint16_t *);
 static int bge_encap(struct bge_softc *, struct mbuf **, uint32_t *);
@@ -2633,6 +2634,8 @@ bge_attach(device_t dev)
 	case BGE_ASICREV_BCM5752:
 	case BGE_ASICREV_BCM5906:
 		sc->bge_flags |= BGE_FLAG_575X_PLUS;
+		if (sc->bge_asicrev == BGE_ASICREV_BCM5906)
+			sc->bge_flags |= BGE_FLAG_SHORT_DMA_BUG;
 		/* FALLTHROUGH */
 	case BGE_ASICREV_BCM5705:
 		sc->bge_flags |= BGE_FLAG_5705_PLUS;
@@ -4060,6 +4063,39 @@ bge_cksum_pad(struct mbuf *m)
 }
 
 static struct mbuf *
+bge_check_short_dma(struct mbuf *m)
+{
+	struct mbuf *n;
+	int found;
+
+	/*
+	 * If device receive two back-to-back send BDs with less than
+	 * or equal to 8 total bytes then the device may hang.  The two
+	 * back-to-back send BDs must in the same frame for this failure
+	 * to occur.  Scan mbuf chains and see whether two back-to-back
+	 * send BDs are there. If this is the case, allocate new mbuf
+	 * and copy the frame to workaround the silicon bug.
+	 */
+	for (n = m, found = 0; n != NULL; n = n->m_next) {
+		if (n->m_len < 8) {
+			found++;
+			if (found > 1)
+				break;
+			continue;
+		}
+		found = 0;
+	}
+
+	if (found > 1) {
+		n = m_defrag(m, M_DONTWAIT);
+		if (n == NULL)
+			m_freem(m);
+	} else
+		n = m;
+	return (n);
+}
+
+static struct mbuf *
 bge_setup_tso(struct bge_softc *sc, struct mbuf *m, uint16_t *mss)
 {
 	struct ip *ip;
@@ -4132,6 +4168,13 @@ bge_encap(struct bge_softc *sc, struct mbuf **m_head, uint32_t *txidx)
 	csum_flags = 0;
 	mss = 0;
 	vlan_tag = 0;
+	if ((sc->bge_flags & BGE_FLAG_SHORT_DMA_BUG) != 0 &&
+	    m->m_next != NULL) {
+		*m_head = bge_check_short_dma(m);
+		if (*m_head == NULL)
+			return (ENOBUFS);
+		m = *m_head;
+	}
 	if ((m->m_pkthdr.csum_flags & CSUM_TSO) != 0) {
 		*m_head = m = bge_setup_tso(sc, m, &mss);
 		if (*m_head == NULL)
diff --git a/sys/dev/bge/if_bgereg.h b/sys/dev/bge/if_bgereg.h
index 60a39f8..8e337c6 100644
--- a/sys/dev/bge/if_bgereg.h
+++ b/sys/dev/bge/if_bgereg.h
@@ -2727,6 +2727,7 @@ struct bge_softc {
 #define	BGE_FLAG_40BIT_BUG	0x01000000
 #define	BGE_FLAG_4G_BNDRY_BUG	0x02000000
 #define	BGE_FLAG_RX_ALIGNBUG	0x04000000
+#define	BGE_FLAG_SHORT_DMA_BUG	0x08000000
 	uint32_t		bge_phy_flags;
 #define	BGE_PHY_WIRESPEED	0x00000001
 #define	BGE_PHY_ADC_BUG		0x00000002