Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller

Eric Dumazet [off-list ref] writes:

On Tue, 2015-11-10 at 16:14 +0000, Mans Rullgard wrote:

quoted

This adds a driver for the Aurora VLSI NB8800 Ethernet controller.
It is an almost complete rewrite of a driver originally found in
a Sigma Designs 2.6.22 tree.

...

quoted

+
+static int nb8800_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct nb8800_priv *priv = netdev_priv(dev);
+	struct nb8800_tx_desc *txd;
+	struct nb8800_tx_buf *txb;
+	struct nb8800_dma_desc *dma;
+	dma_addr_t dma_addr;
+	unsigned int dma_len;
+	unsigned long flags;
+	int align;
+	int next;
+
+	if (atomic_read(&priv->tx_free) <= NB8800_DESC_LOW) {
+		netif_stop_queue(dev);
+		return NETDEV_TX_BUSY;
+	}
+
+	align = (8 - (uintptr_t)skb->data) & 7;
+
+	dma_len = skb->len - align;
+	dma_addr = dma_map_single(&dev->dev, skb->data + align,
+				  dma_len, DMA_TO_DEVICE);
+
+	if (dma_mapping_error(&dev->dev, dma_addr)) {
+		netdev_err(dev, "tx dma mapping error\n");
+		kfree_skb(skb);
+		dev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	if (atomic_dec_return(&priv->tx_free) <= NB8800_DESC_LOW)
+		netif_stop_queue(dev);

You probably also want to clear skb->xmit_more or risk a stall

Very true, will fix.

-- 
Måns Rullgård
mans@mansr.com