Atheros DFS radar detection

[Adrian Chadd]

hi,

would you mind filing a couple of PRs, just so I remember to get this
stuff done:

* please add a HAL method to fetch the default radar parameters;
* please modify the AR5212 HAL to disable some of the fast diversity
stuff if radar is enabled;
* please modify dfs_null to fetch the default radar parameters and
disable the appropriate fast diversity stuff;
* please modify the AR5212 HAL to disable 5GHz ANI operation if radar
reporting is enabled.

I've whacked an AR5212 reference cardbus NIC into a laptop and added
the AR5212 parameters to dfs_null.c. I get around 40 false detects a
second when doing around 25mbit/sec TCP iperf test.

So there may be something specific about your NIC(s) and antenna
setup. I'll try to setup some other 11a NICs (AR5213, AR5312, AR5413,
etc) and see what the story is. I know the AR5212 parameters I have
are working, but I also know the AR5413


Adrian