Major changes:
* Finally tracked down the flow control setting that
seems to have been causing TX stalls and watchdog timeouts
* RX and TX paths now share a lot more code
* TX interrupt is no longer used; we instead GC finished
tx queue entries at the bottom of the start routine.
* TX start now queues fragmented packets directly; it only
invokes defrag() for occasional very fragmented packets.
* "sysctl dev.cpsw" dumps controller statistics and queue counts
* Host Error Interrupt will give extensive debugging information
if the controller chokes on the queued data.
(as used in AM335x SoC for BeagleBone).
Among other things:
* Watchdog reset doesn't hang the driver.
* Disconnecting cable doesn't hang the driver.
* ifconfig up/down doesn't hang the driver
* Out-of-memory no longer panics the driver.
Known issues:
* Doesn't have good support for fragmented packets
(calls m_defrag() on TX, assumes RX packets are never fragmented)
* Promisc and allmulti still unimplimented
* addmulti and delmulti still unimplemented
* TX queue still stalls (but watchdog now consistently recovers in ~5s)
* No sysctl monitoring
* Only supports port0
* No switch configuration support
* Not tested on anything but BeagleBone
Committed from: BeagleBone
