ENGR00180288 - FEC : Fix kernel dump about eth0

Kernel dump when do wifi stress test with suspend and resume as below:
	eth0: tx queue full!.
	remove wake up source irq 103
	PM: resume of devices complete after 348.934 msecs
	Restarting tasks ... done.
	------------[ cut here ]------------
	WARNING: at net/sched/sch_generic.c:255 dev_watchdog+0x284/0x2a8()
	NETDEV WATCHDOG: eth0 (fec): transmit queue 0 timed out
	Modules linked in: ar6000
	[<8004482c>] (unwind_backtrace+0x0/0xf8) from
	[<80068cd0>] (warn_slowpath_common+0x4c/0x64)
	[<80068cd0>] (warn_slowpath_common+0x4c/0x64)from
	[<80068d7c>] (warn_slowpath_fmt+0x30/0x40)
	[<80068d7c>] (warn_slowpath_fmt+0x30/0x40) from
	[<803f0c50>] (dev_watchdog+0x284/0x2a8)
	[<803f0c50>] (dev_watchdog+0x284/0x2a8) from
	[<80074430>] (run_timer_softirq+0xec/0x214)
	[<80074430>] (run_timer_softirq+0xec/0x214) from
	[<8006e524>] (__do_softirq+0xac/0x140)
	[<8006e524>] (__do_softirq+0xac/0x140) from
	[<8006ea60>] (irq_exit+0x94/0x9c)
	[<8006ea60>] (irq_exit+0x94/0x9c) from
	[<80039240>] (do_local_timer+0x54/0x70)
	[<80039240>] (do_local_timer+0x54/0x70) from
	[<8003ea0c>] (__irq_svc+0x4c/0xe8)
	Exception stack(0x80a2bf68 to 0x80a2bfb0)
	bf60:                   0000001f 80a3babc 80a2bfb0 00000000 80a2a000 80a7b8e4
	bf80: 804befcc 80a3ee7c 1000406a 412fc09a 00000000 00000000 80a81440 80a2bfb0
	bfa0: 8003fa64 8003fa68 60000013 ffffffff
	[<8003ea0c>] (__irq_svc+0x4c/0xe8) from [<8003fa68>] (default_idle+0x24/0x28)
	[<8003fa68>] (default_idle+0x24/0x28) from [<8003fc60>] (cpu_idle+0xbc/0xfc)
	[<8003fc60>] (cpu_idle+0xbc/0xfc) from [<80008878>] (start_kernel+0x258/0x29c)
	[<80008878>] (start_kernel+0x258/0x29c) from [<10008040>] (0x10008040)
	---[ end trace 30671ac42e272c2d ]---

But ethernet and system still be alive. In sometime,the issue
will cause system hang like "nfs: server 10.192.242.179 not
responding, still trying".

The root cause is tx buffer descriptors are not cleaned when
ethernet resume back.

Signed-off-by: Fugang Duan <B38611@freescale.com>

diff --git a/drivers/net/fec.c b/drivers/net/fec.c
index f007bf0e7d1382b43f7f31e4b58f26ae354b2830..b1fa4647f911a3e1ba83c8ccf2fa4cf5668e397d 100755 (executable)
--- a/drivers/net/fec.c
+++ b/drivers/net/fec.c
@@ -1456,6 +1456,28 @@ static const struct net_device_ops fec_netdev_ops = {
 #endif
 };
 
+/* Init TX buffer descriptors
+ */
+static void fec_enet_txbd_init(struct net_device *dev)
+{
+       struct fec_enet_private *fep = netdev_priv(dev);
+       struct bufdesc *bdp;
+       int i;
+
+       /* ...and the same for transmit */
+       bdp = fep->tx_bd_base;
+       for (i = 0; i < TX_RING_SIZE; i++) {
+
+               /* Initialize the BD for every fragment in the page. */
+               bdp->cbd_sc = 0;
+               bdp++;
+       }
+
+       /* Set the last buffer to wrap */
+       bdp--;
+       bdp->cbd_sc |= BD_SC_WRAP;
+}
+
  /*
   * XXX:  We need to clean up on failure exits here.
   *
@@ -1512,19 +1534,8 @@ static int fec_enet_init(struct net_device *ndev)
        bdp--;
        bdp->cbd_sc |= BD_SC_WRAP;
 
-       /* ...and the same for transmit */
-       bdp = fep->tx_bd_base;
-       for (i = 0; i < TX_RING_SIZE; i++) {
-
-               /* Initialize the BD for every fragment in the page. */
-               bdp->cbd_sc = 0;
-               bdp->cbd_bufaddr = 0;
-               bdp++;
-       }
-
-       /* Set the last buffer to wrap */
-       bdp--;
-       bdp->cbd_sc |= BD_SC_WRAP;
+       /* Init transmit descriptors */
+       fec_enet_txbd_init(ndev);
 
        fec_restart(ndev, 0);
 
@@ -1575,6 +1586,8 @@ fec_restart(struct net_device *dev, int duplex)
        writel(fep->bd_dma, fep->hwp + FEC_R_DES_START);
        writel((unsigned long)fep->bd_dma + sizeof(struct bufdesc) * RX_RING_SIZE,
                        fep->hwp + FEC_X_DES_START);
+       /* Reinit transmit descriptors */
+       fec_enet_txbd_init(dev);
 
        fep->dirty_tx = fep->cur_tx = fep->tx_bd_base;
        fep->cur_rx = fep->rx_bd_base;