Enable FCS stripping and padding 10 bytes bit of RX MAC control

register. Due to lack of SiS190 controller, I'm not sure whether
this is also applicable to SiS190 so this feature is only activated
on SiS191 controller.
The controller can pad 10 bytes before DMAing a received frame to
RX buffer and received bytes include the padded bytes. This padding
is very useful on strict-alignment architectures because driver
does not have to copy received frame to align IP header on 4 bytes
boundary. It also gives better RX performance on non-strict
alignment architectures. Special thanks to xclin to give me
valuable register information. Without his enthusiastic trial and
errors this wouldn't be even possible.

While I'm here tighten validity check of received frame. Controller
clears RDS_CRCOK bit when it received bad CRC frames. xclin found
that using loop back testing.

Tested by:	xclin <xclin <> cs dot nctu dot edu dot tw >

2 files changed, 32 insertions, 5 deletions

diff --git a/sys/dev/sge/if_sge.c b/sys/dev/sge/if_sge.c
index 813f063..d30f456 100644
--- a/sys/dev/sge/if_sge.c
+++ b/sys/dev/sge/if_sge.c
@@ -1144,7 +1144,8 @@ sge_rxeof(struct sge_softc *sc)
 		if ((rxinfo & RDC_OWN) != 0)
 			break;
 		rxstat = le32toh(cur_rx->sge_sts_size);
-		if (SGE_RX_ERROR(rxstat) != 0 || SGE_RX_NSEGS(rxstat) != 1) {
+		if ((rxstat & RDS_CRCOK) == 0 || SGE_RX_ERROR(rxstat) != 0 ||
+		    SGE_RX_NSEGS(rxstat) != 1) {
 			/* XXX We don't support multi-segment frames yet. */
 #ifdef SGE_SHOW_ERRORS
 			device_printf(sc->sge_dev, "Rx error : 0x%b\n", rxstat,
@@ -1177,11 +1178,23 @@ sge_rxeof(struct sge_softc *sc)
 		/*
 		 * TODO : VLAN hardware tag stripping.
 		 */
-		m->m_pkthdr.len = m->m_len =
-		    SGE_RX_BYTES(rxstat) - ETHER_CRC_LEN;
+		if ((sc->sge_flags & SGE_FLAG_SIS190) == 0) {
+			/*
+			 * Account for 10bytes auto padding which is used
+			 * to align IP header on 32bit boundary.  Also note,
+			 * CRC bytes is automatically removed by the
+			 * hardware.
+			 */
+			m->m_data += SGE_RX_PAD_BYTES;
+			m->m_pkthdr.len = m->m_len = SGE_RX_BYTES(rxstat) -
+			    SGE_RX_PAD_BYTES;
+		} else {
+			m->m_pkthdr.len = m->m_len = SGE_RX_BYTES(rxstat) -
+			    ETHER_CRC_LEN;
 #ifndef __NO_STRICT_ALIGNMENT
-		sge_fixup_rx(m);
+			sge_fixup_rx(m);
 #endif
+		}
 		m->m_pkthdr.rcvif = ifp;
 		ifp->if_ipackets++;
 		SGE_UNLOCK(sc);
@@ -1503,6 +1516,7 @@ sge_init_locked(struct sge_softc *sc)
 {
 	struct ifnet *ifp;
 	struct mii_data *mii;
+	uint16_t rxfilt;
 	int i;
 
 	SGE_LOCK_ASSERT(sc);
@@ -1535,10 +1549,19 @@ sge_init_locked(struct sge_softc *sc)
 	CSR_WRITE_4(sc, RxWakeOnLan, 0);
 	CSR_WRITE_4(sc, RxWakeOnLanData, 0);
 	/* Allow receiving VLAN frames. */
-	CSR_WRITE_2(sc, RxMPSControl, ETHER_MAX_LEN + ETHER_VLAN_ENCAP_LEN);
+	if ((sc->sge_flags & SGE_FLAG_SIS190) == 0)
+		CSR_WRITE_2(sc, RxMPSControl,
+		    ETHER_MAX_LEN + ETHER_VLAN_ENCAP_LEN + SGE_RX_PAD_BYTES);
+	else
+		CSR_WRITE_2(sc, RxMPSControl, ETHER_MAX_LEN + ETHER_VLAN_ENCAP_LEN);
 
 	for (i = 0; i < ETHER_ADDR_LEN; i++)
 		CSR_WRITE_1(sc, RxMacAddr + i, IF_LLADDR(ifp)[i]);
+	/* Configure RX MAC. */
+	rxfilt = 0;
+	if ((sc->sge_flags & SGE_FLAG_SIS190) == 0)
+		rxfilt |= RXMAC_STRIP_FCS | RXMAC_PAD_ENB;
+	CSR_WRITE_2(sc, RxMacControl, rxfilt);
 	sge_rxfilter(sc);
 
 	/* Initialize default speed/duplex information. */
diff --git a/sys/dev/sge/if_sgereg.h b/sys/dev/sge/if_sgereg.h
index 074886e..e8cf514 100644
--- a/sys/dev/sge/if_sgereg.h
+++ b/sys/dev/sge/if_sgereg.h
@@ -137,6 +137,10 @@
 #define	AcceptAllPhys		0x0100
 #define	AcceptErr		0x0020
 #define	AcceptRunt		0x0010
+#define	RXMAC_STRIP_FCS		0x0010
+#define	RXMAC_PAD_ENB		0x0004
+
+#define	SGE_RX_PAD_BYTES	10
 
 /* Station control register. */
 #define	SC_LOOPBACK		0x80000000