Optimize inserting LE for TX checksum computation. Controller does

not require checksum LE configuration if checksum start and write
position is the same as before. So keep track last checksum start
and write position and insert new LE whenever the position is
changed. This reduces number of LEs used in TX path as well as
slightly enhance TX performance.

2 files changed, 17 insertions, 10 deletions

diff --git a/sys/dev/msk/if_msk.c b/sys/dev/msk/if_msk.c
index 38c73f7..0d141d1 100644
--- a/sys/dev/msk/if_msk.c
+++ b/sys/dev/msk/if_msk.c
@@ -738,6 +738,7 @@ msk_init_tx_ring(struct msk_if_softc *sc_if)
 	int i;
 
 	sc_if->msk_cdata.msk_tso_mtu = 0;
+	sc_if->msk_cdata.msk_last_csum = 0;
 	sc_if->msk_cdata.msk_tx_prod = 0;
 	sc_if->msk_cdata.msk_tx_cons = 0;
 	sc_if->msk_cdata.msk_tx_cnt = 0;
@@ -2530,7 +2531,7 @@ msk_encap(struct msk_if_softc *sc_if, struct mbuf **m_head)
 	struct mbuf *m;
 	bus_dmamap_t map;
 	bus_dma_segment_t txsegs[MSK_MAXTXSEGS];
-	uint32_t control, prod, si;
+	uint32_t control, csum, prod, si;
 	uint16_t offset, tcp_offset, tso_mtu;
 	int error, i, nseg, tso;
 
@@ -2709,17 +2710,22 @@ msk_encap(struct msk_if_softc *sc_if, struct mbuf **m_head)
 		if ((sc_if->msk_flags & MSK_FLAG_AUTOTX_CSUM) != 0)
 			control |= CALSUM;
 		else {
-			tx_le = &sc_if->msk_rdata.msk_tx_ring[prod];
-			tx_le->msk_addr = htole32(((tcp_offset +
-			    m->m_pkthdr.csum_data) & 0xffff) |
-			    ((uint32_t)tcp_offset << 16));
-			tx_le->msk_control = htole32(1 << 16 |
-			    (OP_TCPLISW | HW_OWNER));
-			control = CALSUM | WR_SUM | INIT_SUM | LOCK_SUM;
+			control |= CALSUM | WR_SUM | INIT_SUM | LOCK_SUM;
 			if ((m->m_pkthdr.csum_flags & CSUM_UDP) != 0)
 				control |= UDPTCP;
-			sc_if->msk_cdata.msk_tx_cnt++;
-			MSK_INC(prod, MSK_TX_RING_CNT);
+			/* Checksum write position. */
+			csum = (tcp_offset + m->m_pkthdr.csum_data) & 0xffff;
+			/* Checksum start position. */
+			csum |= (uint32_t)tcp_offset << 16;
+			if (csum != sc_if->msk_cdata.msk_last_csum) {
+				tx_le = &sc_if->msk_rdata.msk_tx_ring[prod];
+				tx_le->msk_addr = htole32(csum);
+				tx_le->msk_control = htole32(1 << 16 |
+				    (OP_TCPLISW | HW_OWNER));
+				sc_if->msk_cdata.msk_tx_cnt++;
+				MSK_INC(prod, MSK_TX_RING_CNT);
+				sc_if->msk_cdata.msk_last_csum = csum;
+			}
 		}
 	}
 
diff --git a/sys/dev/msk/if_mskreg.h b/sys/dev/msk/if_mskreg.h
index 2f4e216..75056b6 100644
--- a/sys/dev/msk/if_mskreg.h
+++ b/sys/dev/msk/if_mskreg.h
@@ -2361,6 +2361,7 @@ struct msk_chain_data {
 	bus_dmamap_t		msk_jumbo_rx_ring_map;
 	bus_dmamap_t		msk_jumbo_rx_sparemap;
 	uint16_t		msk_tso_mtu;
+	uint32_t		msk_last_csum;
 	int			msk_tx_prod;
 	int			msk_tx_cons;
 	int			msk_tx_cnt;