Subject: Re: [PATCH] fec: fix tx bounce handling

From: "Tim Sander" <[email-masked]>
Date: Mon, 6 Feb 2012 17:09:31 +0100

Hi

I forward ported the patch i have for 3.0-rt (which was working on a quick test) 
to the net-dev  branch with the patch from Eric mixed in. 

But a quick test revealed that dmesg is full of:
eth0: tx queue full!.
Not good! Any suggestions on this?

Tim

Heres my patch for 3.3:

diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c
index 336edd7..74d5865 100644
--- a/drivers/net/ethernet/freescale/fec.c
+++ b/drivers/net/ethernet/freescale/fec.c
@@ -284,11 +284,6 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
        unsigned short  status;
        unsigned long flags;
 
-       if (!fep->link) {
-               /* Link is down or autonegotiation is in progress. */
-               return NETDEV_TX_BUSY;
-       }
-
        spin_lock_irqsave(&fep->hw_lock, flags);
        /* Fill in a Tx ring entry */
        bdp = fep->cur_tx;
@@ -319,8 +314,8 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
        if (((unsigned long) bufaddr) & FEC_ALIGNMENT) {
                unsigned int index;
                index = bdp - fep->tx_bd_base;
-               memcpy(fep->tx_bounce[index], skb->data, skb->len);
-               bufaddr = fep->tx_bounce[index];
+               bufaddr = PTR_ALIGN(fep->tx_bounce[index], FEC_ALIGNMENT + 1);
+               memcpy(bufaddr, skb->data, skb->len);
        }
 
        /*
@@ -542,6 +537,9 @@ fec_stop(struct net_device *ndev)
                writel(2, fep->hwp + FEC_ECNTRL);
                writel(rmii_mode, fep->hwp + FEC_R_CNTRL);
        }
+
+       netif_stop_queue(ndev);
+       fep->link=0;
 }

@@ -1210,7 +1208,7 @@ static int fec_enet_alloc_buffers(struct net_device *ndev)
 
        bdp = fep->rx_bd_base;
        for (i = 0; i < RX_RING_SIZE; i++) {
-               skb = dev_alloc_skb(FEC_ENET_RX_FRSIZE);
+               skb = __dev_alloc_skb(FEC_ENET_RX_FRSIZE, GFP_KERNEL);
                if (!skb) {
                        fec_enet_free_buffers(ndev);
                        return -ENOMEM;
@@ -1230,6 +1228,10 @@ static int fec_enet_alloc_buffers(struct net_device *ndev)
        bdp = fep->tx_bd_base;
        for (i = 0; i < TX_RING_SIZE; i++) {
                fep->tx_bounce[i] = kmalloc(FEC_ENET_TX_FRSIZE, GFP_KERNEL);
+               if(!fep->tx_bounce[i])  {
+                       fec_enet_free_buffers(ndev);
+                       return -ENOMEM;
+               }
 
                bdp->cbd_sc = 0;
                bdp->cbd_bufaddr = 0;

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