On 27 April 2015 at 11:43, Mitar <mmitar@xxxxxxxxx> wrote: > Hi! > > On OpenWrt, between these versions: > > https://dev.openwrt.org/log/branches/barrier_breaker?action=stop_on_copy&mode=stop_on_copy&rev=44952&stop_rev=42475&limit=200&mail_addr=&mail_addr_confirm= > > there was a regression in how iw set bitrates operate. Because I > suspect it is an upstream issue, I am reporting it here. > > With previous version of our firmware image, I was using the > /etc/hotplug.d/iface/30-bitrates script you can see in this file: > > https://github.com/cloyne/network/blob/349297c8bfd115aa68e3b8c47bb3a7197f1e777f/unifi/README.md > > The goal was to limit on all 2.4 GHz interfaces bitrates to G standard > and higher, removing all legacy stuff. > > It seems it worked. But with an upgrade to the new firmware image, > this script started misbehaving and high-end WiFi devices were able to > connect only with MSC 0. I determined that the issue is in the > following command: > > iw wlan0 set bitrates legacy-2.4 6 9 12 18 24 36 48 54 ht-mcs-2.4 lgi-2.4 > > With this command in effect, my client has in station dump the > following bitrates: > > tx bitrate: 6.5 MBit/s MCS 0 > rx bitrate: 216.7 MBit/s MCS 23 short GI With the above command you basically disable HT rates since you say "ht-mcs-2.4" but specify no MCS indexes to use. > If I change the command to: > > iw wlan0 set bitrates legacy-2.4 6 9 12 18 24 36 48 54 > > tx bitrate: 195.0 MBit/s MCS 23 > rx bitrate: 216.7 MBit/s MCS 23 short GI In this you effectively disable CCK (11b) rates and leave OFDM (11g), and you leave HT rates untouched (i.e. allow HT to be used). > > Which is the expected bitrate. > > If I run only: > > iw wlan0 set bitrates ht-mcs-2.4 > > tx bitrate: 11.0 MBit/s > rx bitrate: 117.0 MBit/s MCS 20 > > This goes against the documentation which is saying that this should > reset bitrates masks to normal: > > https://wireless.wiki.kernel.org/en/users/documentation/iw#modifying_tx_ht_mcs_bitrates It seems the docs err on this. To reset bitrates to normal you need to issue: iw wlanX set bitrates (no arguments follow) > Maybe I am not using the command correctly. In general it is unclear > what should be correct behavior here. I also opened a SuperUser > question: > > http://superuser.com/questions/881025/limiting-low-bitrates-with-iw-on-ath9k > > So maybe clearer documentation would make it easier to know what is > the correct command? So, what is current (and hopefully future proof) > command to not allow legacy bitrates, but to allow any other (which > would work also on future devices without having to modify the list of > allowed MCS when they are added)? I don't recall bitrates command ever changed behaviour. Apparently the docs were always incorrect I guess? Michał -- 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
