8139cp: Dump contents of descriptor ring on TX timeout

We are seeing unexplained TX timeouts under heavy load. Let's try to get
a better idea of what's going on.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/realtek/8139cp.c b/drivers/net/ethernet/realtek/8139cp.c
index ec6bd86..686334f 100644 (file)
--- a/drivers/net/ethernet/realtek/8139cp.c
+++ b/drivers/net/ethernet/realtek/8139cp.c
@@ -157,6 +157,7 @@ enum {
        NWayAdvert      = 0x66, /* MII ADVERTISE */
        NWayLPAR        = 0x68, /* MII LPA */
        NWayExpansion   = 0x6A, /* MII Expansion */
+       TxDmaOkLowDesc  = 0x82, /* Low 16 bit address of a Tx descriptor. */
        Config5         = 0xD8, /* Config5 */
        TxPoll          = 0xD9, /* Tell chip to check Tx descriptors for work */
        RxMaxSize       = 0xDA, /* Max size of an Rx packet (8169 only) */
@@ -1234,7 +1235,7 @@ static void cp_tx_timeout(struct net_device *dev)
 {
        struct cp_private *cp = netdev_priv(dev);
        unsigned long flags;
-       int rc;
+       int rc, i;
 
        netdev_warn(dev, "Transmit timeout, status %2x %4x %4x %4x\n",
                    cpr8(Cmd), cpr16(CpCmd),
@@ -1242,6 +1243,17 @@ static void cp_tx_timeout(struct net_device *dev)
 
        spin_lock_irqsave(&cp->lock, flags);
 
+       netif_dbg(cp, tx_err, cp->dev, "TX ring head %d tail %d desc %x\n",
+                 cp->tx_head, cp->tx_tail, cpr16(TxDmaOkLowDesc));
+       for (i = 0; i < CP_TX_RING_SIZE; i++) {
+               netif_dbg(cp, tx_err, cp->dev,
+                         "TX slot %d @%p: %08x (%08x) %08x %llx %p\n",
+                         i, &cp->tx_ring[i], le32_to_cpu(cp->tx_ring[i].opts1),
+                         cp->tx_opts[i], le32_to_cpu(cp->tx_ring[i].opts2),
+                         le64_to_cpu(cp->tx_ring[i].addr),
+                         cp->tx_skb[i]);
+       }
+
        cp_stop_hw(cp);
        cp_clean_rings(cp);
        rc = cp_init_rings(cp);