[RFC] mac80211: Allow AP to change channels for DFS support

[Wojciech Dubowik <dubowoj@neratec.com>]

Hello,

  I have started studying DFS support possibilities in ath9k 
and I have noticed that at the moment AP is not allowed to 
change channels when it's using beacons.

I have found that I can go around it by setting CHAN_MODE_UNDEFINED
for this case. Not sure whether we need extra mode for it but
to me this is a case when AP is neither fixed nor hopping.

--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c 
@@ -34,8 +34,11 @@
 				return CHAN_MODE_HOPPING;
 		}
 
-		if (sdata->vif.type == NL80211_IFTYPE_AP &&
-		    !sdata->u.ap.beacon)
+
+		/* TODO: CHAN_MODE_FIXED shouldn't be set when
+		  AP is on DFS channel. For now assume always
+		  undefined */
+		if (sdata->vif.type == NL80211_IFTYPE_AP)
 			continue;
 
 		return CHAN_MODE_FIXED;


It's also possible to check whether channel is of radar type
and set mode undefined for this case. Question is whether it's 
needed at all.

Any comments?

Br,
Wojtek