On Sun, 2011-01-02 at 23:15 -0800, Daniel Halperin wrote: > I'm trying to track down an anomaly with a 3-stream 802.11n AP. > iwlwifi is saying that a single antenna should be sufficient even when > the AP supports 3 streams. Here's what I've tracked down: > Code in iwl-agn-rxon.c uses the ht_cap TX MCS parameters to determine > how many streams the other side supports: > <http://git.kernel.org/?p=linux/kernel/git/iwlwifi/iwlwifi-2.6.git;a=blob;f=drivers/net/wireless/iwlwifi/iwl-agn-rxon.c;h=d33e4db7e56cab88abc3281d04adf32162b8020e;hb=HEAD#l470> > Yet, it looks like mac80211 doesn't actually set those variables at > all! In net/mac80211/ht.c, when converting the IE to the Station HT > cap: > <http://git.kernel.org/?p=linux/kernel/git/iwlwifi/iwlwifi-2.6.git;a=blob;f=net/mac80211/ht.c;h=75d679d75e63e92143d55a47601a1dfc1377ba03;hb=HEAD#l21> > we first zero out the HT CAP (line 30) and then never actually set the > ht_cap->mcs.tx_params variables at all. Grep says that's the only use > of mcs.tx_params in that directory, so I'm pretty confident mac80211 > just never does that. Thus iwlwifi thinks it only needs to have 1 RX > antenna enabled (though it defaults to a minimum of 2 when possible) > and basically fails to receive 3 stream packets. > Is this a bug in iwlwifi or mac80211? It sure looks like a bug. mac80211 should fill the info I guess, but iwlwifi also shouldn't use this weird calculation anyhow ... I've been meaning to move the # of chains calculation to mac80211 for a while now... maybe this is the time to do that. 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
