On 14/11/2012 14:38, Johannes Berg wrote:
On Wed, 2012-11-14 at 13:19 +0100, Michal Kazior wrote:
However, then I realised that that still doesn't work -- once initial
radar detection is done, it needs to continue while the AP is active. If
the channel context was going to be relinquished, or even just the
channel changed for a few seconds, it would be unsafe. So as a result,
the radar detect operation has to somehow be coupled to the start AP
operation and prohibit channel changes and additional channel contexts
during the entire operation time.
Hmm.. cfg80211 doesn't really know about channel contexts.
The problem I see is that cfg80211 may be in a combination with
`num_different_channels = 1` and mac80211 can have 2 channel contexts
due to channel type incompatibilities.
Yes, this is a concern, we need to fix that anyway though, otherwise it
may assume that some operations are possible when they really aren't
(e.g. starting an HT40+ and HT40- AP on the same channel, which
shouldn't be done anyway, but still)
not sure how it can happen if have this check:
if ((cac_type != NL80211_CHAN_HT20) && (cac_type != NL80211_CHAN_NO_HT))
return -EOPNOTSUPP;
in both start_radar_detection() & enable_tx() ?
We'd need to tell cfg80211 that multi-interface is not possible when DFS
is active if we want to at least consider single-channel only DFS.
Not sure about multi-interface, but multi-channel at least.
Agree, maybe you have an idea how we should do this ?
--
Thanks,
Victor.
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