Re: [PATCH v3] Ethernet driver for the WIZnet W5300 chip

From: Mike Sinkovsky
Date: Mon Mar 26 2012 - 05:05:25 EST

24.03.2012 22:10, Eric Dumazet wrote:
As there is no tx interrupt at the end of transmit to eventually XON the
queue, you cant XOFF it when there it no room in transmit queue.

Actually there is, but is unused in original driver, don't know why.

Rule to use NETDEV_TX_BUSY is :

Before returning NETDEV_TX_BUSY, qdisc must have been stopped by
netif_stop_queue(ndev) (and tx completion might call netif_wake_queue()

I tried handle this situation, and it seems to work perfectly:

@@ -377,7 +377,8 @@ static int w5300_start_tx(struct sk_buff *skb, struct net_device *ndev)
struct w5300_private *priv = netdev_priv(ndev);

if (unlikely(w5300_read32(priv, W5300_S0_TX_FSR) < skb->len)) {
- ndev->stats.tx_dropped++;
+ netif_stop_queue(ndev);
+ w5300_write(priv, W5300_S0_IMR, S0_IR_RECV | S0_IR_SENDOK);

@@ -443,6 +444,12 @@ static irqreturn_t w5300_interrupt(int irq, void *ndev_instance)

+ if (unlikely(netif_queue_stopped(ndev))) {
+ w5300_write(priv, W5300_S0_IR, S0_IR_SENDOK);
+ w5300_write(priv, W5300_S0_IMR, S0_IR_RECV);
+ netif_wake_queue(ndev);
+ }


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