On Fri, Jan 1, 2010 at 4:07 AM, Benoit PAPILLAULT <benoit.papillault@xxxxxxx> wrote: > Hello, > > I'd like to report an issue I have when trying to connect a laptop > running ath9k to a 802.11n AP in HT40 mode. What happens is that the > laptop cannot associate if the AP is running in HT40 mode. Association > is OK if the AP is running in HT20 mode. Here is an excerpt from syslog : > > [ 577.166241] wlan0: associate with AP 00:15:6d:e8:88:84 (try 1) > [ 577.167448] wlan0: RX AssocResp from 00:15:6d:e8:88:84 (capab=0x411 > status=10 aid=257) > [ 577.167451] wlan0: AP denied association (code=10) > [ 577.167460] wlan0: deauthenticating from 00:15:6d:e8:88:84 by local > choice (reason=3) > > What's wrong is that the Associate Request (built by > ieee80211_send_assoc) does not set the bit in HT Capabilities IE saying > : "The station supports both HT20 & HT40". > > Looking into the code, it appears that both (flags & > IEEE80211_CHAN_NO_HT40PLUS) and (flags & IEEE80211_CHAN_NO_HT40MINUS) > are true, thus disabling the IEEE80211_HT_CAP_SUP_WIDTH_20_40 which is > the culprit mentioned above. > > Digging further down, both flags are set in reg.c by : > if (freq_range->max_bandwidth_khz < MHZ_TO_KHZ(40)) > bw_flags = IEEE80211_CHAN_NO_HT40; > > Indeed, at this stage, max_bandwidth_khz is 20 MHz only... Looking up in > my syslog, I found this : > > [ 506.036923] cfg80211: Received country IE: > [ 506.036927] cfg80211: Regulatory domain: FR > [ 506.036928] (start_freq - end_freq @ bandwidth), > (max_antenna_gain, max_eirp) > [ 506.036931] (5170000 KHz - 5190000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036933] (5190000 KHz - 5210000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036936] (5210000 KHz - 5230000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036938] (5230000 KHz - 5250000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036940] (5250000 KHz - 5270000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036943] (5270000 KHz - 5290000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036945] (5290000 KHz - 5310000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036948] (5310000 KHz - 5330000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036950] (5490000 KHz - 5510000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036952] (5510000 KHz - 5530000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036955] (5530000 KHz - 5550000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036957] (5550000 KHz - 5570000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036959] (5570000 KHz - 5590000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036962] (5590000 KHz - 5610000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036964] (5610000 KHz - 5630000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036966] (5630000 KHz - 5650000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036969] (5650000 KHz - 5670000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036971] (5670000 KHz - 5690000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > [ 506.036974] (5690000 KHz - 5710000 KHz @ 40000 KHz), (10000 mBi, > 10000 mBm) > > [ 506.036975] cfg80211: CRDA thinks this should applied: > [ 506.036976] cfg80211: Regulatory domain: FR > [ 506.036978] (start_freq - end_freq @ bandwidth), > (max_antenna_gain, max_eirp) > [ 506.036980] (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm) > [ 506.036982] (5170000 KHz - 5250000 KHz @ 40000 KHz), (N/A, 2000 mBm) > [ 506.036984] (5250000 KHz - 5330000 KHz @ 40000 KHz), (N/A, 2000 mBm) > [ 506.036987] (5490000 KHz - 5710000 KHz @ 40000 KHz), (N/A, 2700 mBm) > > [ 506.036988] cfg80211: We intersect both of these and get: > [ 506.037005] cfg80211: Regulatory domain: 98 > [ 506.037006] (start_freq - end_freq @ bandwidth), > (max_antenna_gain, max_eirp) > [ 506.037008] (5170000 KHz - 5190000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037011] (5190000 KHz - 5210000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037013] (5210000 KHz - 5230000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037015] (5230000 KHz - 5250000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037017] (5250000 KHz - 5270000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037019] (5270000 KHz - 5290000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037021] (5290000 KHz - 5310000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037024] (5310000 KHz - 5330000 KHz @ 20000 KHz), (N/A, 2000 mBm) > [ 506.037026] (5490000 KHz - 5510000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037028] (5510000 KHz - 5530000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037030] (5530000 KHz - 5550000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037032] (5550000 KHz - 5570000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037035] (5570000 KHz - 5590000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037037] (5590000 KHz - 5610000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037039] (5610000 KHz - 5630000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037041] (5630000 KHz - 5650000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037043] (5650000 KHz - 5670000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037045] (5670000 KHz - 5690000 KHz @ 20000 KHz), (N/A, 2700 mBm) > [ 506.037047] (5690000 KHz - 5710000 KHz @ 20000 KHz), (N/A, 2700 mBm) > > So, at this stage, max_bandwidth_khz is indeed 20 MHz! > > What's the real meaning of max_bandwidth_khz? If this is just the > difference between the upper/lower frequency of each channels, then it's > useless. If it is a capability features saying 40 MHz channel wide are > allowed, then it should be left to 40 MHz even if upper/lower > frequencies are only 20 MHz apart (since the ability to use 40 MHz > depends on the list of all frequencies, not a single frequency). Your AP is sending a country IE channel triplet for each channel it allows. Its the first time I see an AP do this and its good that you report this. What AP do you have? reg.c treats each triplet as a regulatory rule though and since you have a rule for each channel it will restrict this to the triplet range which is just one channel and as such 20 MHz only makes sense. A fix would be to expand on the ht40 checks to check connecting frequency rules. Luis -- 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
