Hi

On 02/02/2012 01:38 PM, Tim Sander wrote:
 > Mh, i think i am hit by the same problem. I have a i.mx 35 and when dhcp
 > is enabled the ksoftirq is also running wild with 3.0-rt. This also
 > happens when static ip is configured and the probably during network
 > transfer the network interface is reconfigured. Basically it seems the
 > sirq-net-tx thread tries to send a packet on a non configured
 > interface.
 > 
 > But one thing that makes me thinking, is that this thing is only
 > happening on arm and not on x86. So Hector what platform are you
 > working on. Are you by chance using the same fec.c ethernet driver?

I'm working on an i.MX51 and using the fec.c driver as well. Interesting
that it is not happening on x86.

Well, at least no one else spoke out on this problem before

 > I have verified that in my case the driver takes always the return
 > statement in line fec.c:247: return NETXDEV_TX_BUSY;
 > It never stops on a breakpoint set on line 250 which shows that the
 > interface gets never configured.

Autonegotiation is triggered by phy_state_machine() at phy.c which is
scheduled as a delayed work by phy_device.c upon PHY device creation.
This is not even started when the fec_enet_start_xmit() function is called.

 > I have taken some screenshots of my hw debugger:
trace:http://private.vlsi.informatik.tu-darmstadt.de/tstone/linux/fec_enet_
start_xmit.png

stack:http://private.vlsi.informatik.tu-darmstadt.de/tstone/linux/fec_enet_
start_xmit_stacktrace.png

locals:http://private.vlsi.informatik.tu-darmstadt.de/tstone/linux/fec_enet
_start_xmit_stack+locals.png

 > Whats interesting to note is that phy_dev and mii_dev are both null
 > pointers.

I'll check this but it is probably because the PHY device is not yet
created or initialized.

Well the phy seems to be initialized in fec_enet_open->fec_enet_mii_probe.
But opened is set to 0 so this codepath has not been run, so not initialized.
If the device is not opended how does it tries to send packets?

Best regards
Tim

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