[ath9k-devel] AR9380 + hostapd + HT over 802.11a

[Ben Greear <greearb@candelatech.com>]

On 05/31/2011 10:36 AM, Mihai Moldovan wrote:
> Hey all,
>
> I'm having a "problem" again. ;)
>
> Today I got my AR9380 card and wanted to set it up on 802.11a (5GHz)
> with HT40 (802.11n).
>
> Although enabling 802.11d and setting the regulatory domain to "DE"
> (Germany), I wasn't able to bring up the card on any 5GHz channel in AP
> mode.
>
> Finding some "patch" for ath9k which disabled NO_IBSS, RADAR_SCANNING
> and PASSIVE_SCAN, I was able to bring the card up on 5GHz with HT (and
> finally get 300MBit max rate.)
>
> I feel that's the wrong approach and would like to ask how to really do
> this kind of stuff.
>
> Also: as the card is currently running on 5GHz, I'd like to put another
> card up running on 2.4GHz for legacy hardware not capable of 802.11a
> (for instance my Android phone.)
>
> Is there anything I should pay attention to? For instance using another
> ESSID and (naturally) using some 2.4GHz channel. In my experience,
> running two cards on the same ESSID on different channels doesn't work
> well and confuses STAs, leading to connection drops and unrecoverable
> states.
>
> Any help is highly appreciated.

Probably your NIC is in regdomain 0x6a or similar.

If you see something like this in your logs that is the problem:


ath: EEPROM regdomain: 0x6a
ath: EEPROM indicates we should expect a direct regpair map
ath: Country alpha2 being used: 00
ath: Regpair used: 0x6a

cfg80211: Calling CRDA for country: US
cfg80211: Regulatory domain changed to country: US
cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
cfg80211:     (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2700 mBm)
cfg80211:     (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 1700 mBm)
cfg80211:     (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
cfg80211:     (5490000 KHz - 5600000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
cfg80211:     (5650000 KHz - 5710000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
cfg80211:     (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm)


You can over-ride this with a patch similar to this one:
http://patches.aircrack-ng.org/ath9k_regdomain_override.patch

(That patch may not apply to your kernel, but it's not too hard to
make it work.)  Find your domain for DE and just use that.  I used
0x0, which evidently is basically US (here in the USA) to get some
of the 5Ghz channels working in AP mode).

Note that you may lose 'official' support by doing this, but as far
as I can tell, as long as you use the correct domain with 'iw reg set'
you will still be in regulatory compliance as it chooses the minimal
set of features supported by the NIC and whatever 'iw reg set' does.

If you use 0x0 and 'iw set US' then you are likely out of compliance
in Germany, for instance.

Thanks,
Ben

>
> Best regards,
>
>
> Mihai
>
>
>
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-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com