[LEDE-DEV] [PATCH] ag71xx: Add some unlikely calls + rearange some stuff in hard_start_xmit.

[Rosen Penev]

Based on Qualcomm driver. Improves iperf3 throughput by ~20mbps on transmit on 
Archer C7v4.

Signed-off-by: Rosen Penev <ros...@gmail.com>
---
 .../drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c      | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git 
a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c 
b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
index 95682b7641..d32f220178 100644
--- 
a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
+++ 
b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
@@ -797,11 +797,14 @@ static netdev_tx_t ag71xx_hard_start_xmit(struct sk_buff 
*skb,
        if (ag71xx_has_ar8216(ag))
                ag71xx_add_ar8216_header(ag, skb);
 
-       if (skb->len <= 4) {
+       dma_cache_sync (NULL, skb->data, skb->len, DMA_TO_DEVICE);
+
+       if (unlikely(skb->len <= 4)) {
                DBG("%s: packet len is too small\n", ag->dev->name);
                goto err_drop;
        }
 
+       netdev_sent_queue(dev, skb->len);
        dma_addr = dma_map_single(&dev->dev, skb->data, skb->len,
                                  DMA_TO_DEVICE);
 
@@ -817,27 +820,24 @@ static netdev_tx_t ag71xx_hard_start_xmit(struct sk_buff 
*skb,
        ring->buf[i].len = skb->len;
        ring->buf[i].skb = skb;
 
-       netdev_sent_queue(dev, skb->len);
-
        skb_tx_timestamp(skb);
 
        desc->ctrl &= ~DESC_EMPTY;
        ring->curr += n;
 
-       /* flush descriptor */
-       wmb();
-
        ring_min = 2;
        if (ring->desc_split)
            ring_min *= AG71XX_TX_RING_DS_PER_PKT;
 
-       if (ring->curr - ring->dirty >= ring_size - ring_min) {
+       if (unlikely(ring->curr - ring->dirty >= ring_size - ring_min)) {
                DBG("%s: tx queue full\n", dev->name);
                netif_stop_queue(dev);
        }
 
        DBG("%s: packet injected into TX queue\n", ag->dev->name);
 
+       /* flush descriptor */
+       wmb();
        /* enable TX engine */
        ag71xx_wr(ag, AG71XX_REG_TX_CTRL, TX_CTRL_TXE);
 
-- 
2.14.3


_______________________________________________
Lede-dev mailing list
Lede-dev@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/lede-dev