Driver Seems to Die if Channel is Too Busy

[bradjc]

I'm seeing an issue where no more packets are sent or received after three "channel busy" detections. The kern.log output is:

Mar 27 22:29:38 raspberrypi kernel: [23663.893466] [cc2520] - channel still busy, waiting 1901 uS
Mar 27 22:31:57 raspberrypi kernel: [23803.039498] [cc2520] - channel still busy, waiting 1640 uS
Mar 27 22:34:43 raspberrypi kernel: [23968.961506] [cc2520] - channel still busy, waiting 1770 uS

I'm not sure why 3 seems to be the magic number, but this has happened more than once. If I decide to dive in I'll poke around, but I wanted to make sure to record this now.