Re: [PATCH net-next V5 6/9] Altera TSE: Add main and header file for Altera Ethernet Driver

On Fri, Mar 14, 2014 at 09:04:44AM -0500, Vince Bridgers wrote:

+static int tse_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct altera_tse_private *priv = netdev_priv(dev);
+	unsigned int txsize = priv->tx_ring_size;
+	unsigned int entry;
+	struct tse_buffer *buffer = NULL;
+	int nfrags = skb_shinfo(skb)->nr_frags;
+	unsigned int nopaged_len = skb_headlen(skb);
+	enum netdev_tx ret = NETDEV_TX_OK;
+	dma_addr_t dma_addr;
+	int txcomplete = 0;
+
+	spin_lock_bh(&priv->tx_lock);
+
+	if (unlikely(tse_tx_avail(priv) < nfrags + 1)) {
+		if (!netif_queue_stopped(dev)) {
+			netif_stop_queue(dev);
+			/* This is a hard error, log it. */
+			netdev_err(priv->dev,
+				   "%s: Tx list full when queue awake\n",
+				   __func__);
+		}
+		ret = NETDEV_TX_BUSY;
+		goto out;
+	}
+
+	/* Map the first skb fragment */
+	entry = priv->tx_prod % txsize;
+	buffer = &priv->tx_ring[entry];
+
+	dma_addr = dma_map_single(priv->device, skb->data, nopaged_len,
+				  DMA_TO_DEVICE);
+	if (dma_mapping_error(priv->device, dma_addr)) {
+		netdev_err(priv->dev, "%s: DMA mapping error\n", __func__);
+		ret = NETDEV_TX_OK;
+		goto out;
+	}
+
+	buffer->skb = skb;
+	buffer->dma_addr = dma_addr;
+	buffer->len = nopaged_len;
+
+	/* Push data out of the cache hierarchy into main memory */
+	dma_sync_single_for_device(priv->device, buffer->dma_addr,
+				   buffer->len, DMA_TO_DEVICE);
+
+	txcomplete = priv->dmaops->tx_buffer(priv, buffer);
+
+	priv->tx_prod++;
+	dev->stats.tx_bytes += skb->len;

This could use a call to skb_tx_timestamp() somewhere around here.

+
+	if (unlikely(tse_tx_avail(priv) <= TXQUEUESTOP_THRESHHOLD)) {
+		if (netif_msg_hw(priv))
+			netdev_dbg(priv->dev, "%s: stop transmitted packets\n",
+				   __func__);
+		netif_stop_queue(dev);
+	}
+
+out:
+	spin_unlock_bh(&priv->tx_lock);
+
+	return ret;
+}

Thanks,
Richard