On 1/29/2013 1:17 AM, Troy Kisky wrote:

On 1/28/2013 10:39 AM, Vikram Narayanan wrote:

quoted

Running the latest head <linux-2.6.git> on an i.Mx6Quad based platform
gives me the below error when flooded with ping requests.

== Start log ==
[ 2555.004031] ------------[ cut here ]------------
[ 2555.009740] WARNING: at net/sched/sch_generic.c:254
dev_watchdog+0x298/0x2b8()
[ 2555.018721] NETDEV WATCHDOG: eth0 (fec): transmit queue 0 timed out

I think the tx interrupt status bit was lost. The packets were
transmitted, but the interrupt never
happened. The controller should have been reset here, but perhaps a bug
with the reset code.
Are you using the mainline kernel, or a version Freescale's kernel.

I tried with both the kernels. Freescale's and mainline results in the 
same error.

mainline fec_restart does not reset tx_full

You can try adding
fep->tx_full = 0;

With this there was no improvement.

to fec_restart, though it would be better to call fec_enet_tx in
fec_timeout
and skip the call to fec_restart if it returns some packets.

fec_enet_tx returns void, how do I check for the return packets.
I'm sorry, I couldn't get your point here.

quoted

[ 2555.026733] Modules linked in:
[ 2555.030598] Backtrace:
[ 2555.034252] [<800119c8>] (dump_backtrace+0x0/0x10c) from
[<803b8494>] (dump_stack+0x18/0x1c)
[ 2555.044438]  r6:000000fe r5:80302f64 r4:80503dd0 r3:80510e80
[ 2555.052019] [<803b847c>] (dump_stack+0x0/0x1c) from [<8001df08>]
(warn_slowpath_common+0x54/0x6c)
[ 2555.062679] [<8001deb4>] (warn_slowpath_common+0x0/0x6c) from
[<8001dfc4>] (warn_slowpath_fmt+0x38/0x40)
[ 2555.073936]  r8:8052ebf1 r7:805040c0 r6:00000000 r5:8f9771d4
r4:8f977000
r3:00000009
[ 2555.084816] [<8001df8c>] (warn_slowpath_fmt+0x0/0x40) from
[<80302f64>] (dev_watchdog+0x298/0x2b8)
[ 2555.095535]  r3:8f977000 r2:8049f6d4
[ 2555.099868] [<80302ccc>] (dev_watchdog+0x0/0x2b8) from [<8002acf8>]
(call_timer_fn.isra.33+0x2c/0x8c)
[ 2555.110794] [<8002accc>] (call_timer_fn.isra.33+0x0/0x8c) from
[<8002af48>] (run_timer_softirq+0x1f0/0x204)
[ 2555.122240]  r7:80571114 r6:805040c0 r5:00000000 r4:80570900
[ 2555.129894] [<8002ad58>] (run_timer_softirq+0x0/0x204) from
[<80025750>] (__do_softirq+0xc8/0x180)
[ 2555.140599] [<80025688>] (__do_softirq+0x0/0x180) from [<80025b40>]
(irq_exit+0x88/0x90)
[ 2555.150492] [<80025ab8>] (irq_exit+0x0/0x90) from [<8000ec58>]
(handle_IRQ+0x44/0x98)
[ 2555.160112]  r4:804ffde0 r3:00000220
[ 2555.164848] [<8000ec14>] (handle_IRQ+0x0/0x98) from [<80008540>]
(gic_handle_irq+0x30/0x64)
[ 2555.174956]  r6:80503f28 r5:8050a518 r4:f400010c r3:00000000
[ 2555.182694] [<80008510>] (gic_handle_irq+0x0/0x64) from
[<8000df80>] (__irq_svc+0x40/0x50)
[ 2555.192737] Exception stack(0x80503f28 to 0x80503f70)
[ 2555.198639] 3f20:                   8052f150 a0000093 00000000
00000000 80502000 8052ed08
[ 2555.208600] 3f40: 8050a4f4 803bfaec 8050df00 412fc09a 80502000
80503f7c 80503f80 80503f70
[ 2555.218584] 3f60: 8000eee4 8000eee8 60000013 ffffffff
[ 2555.224730]  r7:80503f5c r6:ffffffff r5:60000013 r4:8000eee8
[ 2555.232292] [<8000eeb8>] (default_idle+0x0/0x38) from [<8000f0d8>]
(cpu_idle+0xcc/0x114)
[ 2555.242204] [<8000f00c>] (cpu_idle+0x0/0x114) from [<803b3718>]
(rest_init+0x64/0x7c)
[ 2555.251858] [<803b36b4>] (rest_init+0x0/0x7c) from [<804cc7dc>]
(start_kernel+0x258/0x298)
[ 2555.261963] [<804cc584>] (start_kernel+0x0/0x298) from [<10008078>]
(0x10008078)
[ 2555.271167] ---[ end trace 3d2ffb53e6fe41f3 ]---
[ 2555.277270] eth0: tx queue full!.
[ 2555.288776] eth0: tx queue full!.
[ 2555.293594] eth0: tx queue full!.
[ 2555.297944] eth0: tx queue full!.
[ 2555.302229] eth0: tx queue full!.

All the packet have been transmitted but the transmit queue is full, so
no more
tx interrupts can happen to replace the previously lost tx interrupt.

I've seen MII interrupts clear the TX interrupt status bit.

Do you suspect the MAC <-> PHY interconnect? I'm having an MII interface.

Regards,
Vikram