On Thu, 2013-01-17 at 14:52 +0100, Simon Wunderlich wrote: > > > + res = drv_start_radar_detection(local, sdata, chandef); > > > > If the vif is assigned the channel, why also pass it to the > > start_radar_detection command? That seems pointless, they can't be > > different? > > > In the initial phase, __nl80211_set_channel() should not be able to set > the channel (no CAC yet), and will fail for IBSS (to be implemented later) > generally, at least as it's implemented now. > > But what we can do is set the channel from mac80211 and call the driver > function without the channel argument, as it'll be pointless in this case. > Is this what you mean? Hmm. Why are you talking about __nl80211_set_channel() now? We're now talking about mac80211, which can and does set the channel (chanctx, which may fall back to drv_config()) before calling drv_start_radar_detection(), so I think the latter needs no chandef argument? > > Actually that raises another question: If we have "external" radar > > detection, say by a different NIC, then shouldn't we still ask the > > driver to start radar detection when using the channel? Or is that > > implicit, does the driver have to check? > > That is a good question, I didn't consider that. In the "simple process" > we first start radar detection and start the ap on the same channel. > For external CAC that won't work, of course. What about mac80211 checking > the channel in start_ap(), and if the channel requires DFS, pass some flag > to the driver that radar detection should be enabled? Yes, that makes sense. But then it would also make sense to remove the start_radar_detection() callback entirely, and encode all that information in the channel context/drv_config call? If mac80211 gets to be responsible for it, this should totally be documented in the cfg80211 API though so if a full-mac driver wants to implement it they know what to do. I do think this is the reasonable way of doing it though. Note that I'm not advocating removing the start_radar_detection() or its chandef from the *cfg80211* API. That is clearly needed. But in mac80211 it seems "set this chandef with radar detection" is a better API? > > > +#define CHAN_DEF_ENTRY __field(enum ieee80211_band, band) \ > > > > I'll apply my "mac80211: split out chandef tracing macros" patch > > instead. > > OK. Done, though it seems you don't need it if you remove the chandef argument from start_radar_detection, or even remove the callback entirely. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
