Re: second wifi card enforce CN reg dom

Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx> · Thu, 12 Apr 2018 09:48:42 +0200

On 4/12/2018 9:00 AM, solsTiCe d'Hiver wrote:
Nobody cares about this ?

Should I report this as a bug to the LKML ? or elsewhere ? to
ath9k_htc dev ? to crda dev ?

Please.

Hi,

I do not think nobody cares, but what you describe is actually no issue 
as far as I can determine. Wifi cards are typically programmed with some 
country code and both provide that as a regulatory hint to the 
regulatory framework, which adapts to a regulatory domain in which only 
channels and power limits are set that are allowed for both devices. 
That is why some of the rules in the global set #98 are matching the FR 
set and some rules match the CN set. And because FR uses ETSI DFS and CN 
uses FCC DFS you are loosing all channels that require DFS.

Regards,
Arend

2018-04-10 21:57 GMT+02:00 solsTiCe d'Hiver <solstice.dhiver@xxxxxxxxx>:
hi.

I am trying to capture on 2 channels at the same time with 2 cards.

One card is TP-Link TL-W722N v1 using ath9k_htc and the second one is
an Alfa AWUS051NH v2 using rt2800usb.

I have tried this, first, on raspberry pi 0 W  using archlinux-arm and
reproduced the issue on a netbook using archlinux x64 too using latest
kernel and drivers. (seems to happen on ubuntu 17.10 on dell laptop
too)

So when the Alfa card is used alone using the default reg dom FR, one
can change to 112 channel for example (using iw dev wlan1 set channel
112)

But once the tp-link is plugged in, reg dom seems to become CN and one
can't change the alfa card to 112 channel.

iw reg get output change from
global
country FR: DFS-ETSI
(2402 - 2482 @ 40), (N/A, 20), (N/A)
(5170 - 5250 @ 80), (N/A, 20), (N/A), AUTO-BW
(5250 - 5330 @ 80), (N/A, 20), (0 ms), DFS, AUTO-BW
(5490 - 5710 @ 160), (N/A, 27), (0 ms), DFS
(57000 - 66000 @ 2160), (N/A, 40), (N/A)
to
global
country 98: DFS-UNSET
(2402 - 2482 @ 40), (N/A, 20), (N/A)
(5170 - 5250 @ 80), (N/A, 20), (N/A), AUTO-BW
(5250 - 5330 @ 80), (N/A, 20), (0 ms), DFS, AUTO-BW
(57240 - 59400 @ 2160), (N/A, 28), (N/A)
(59400 - 63720 @ 2160), (N/A, 40), (N/A)
(63720 - 65880 @ 2160), (N/A, 28), (N/A)

phy#2
country CN: DFS-FCC
(2402 - 2482 @ 40), (N/A, 20), (N/A)
(5170 - 5250 @ 80), (N/A, 23), (N/A), AUTO-BW
(5250 - 5330 @ 80), (N/A, 23), (0 ms), DFS, AUTO-BW
(5735 - 5835 @ 80), (N/A, 30), (N/A)
(57240 - 59400 @ 2160), (N/A, 28), (N/A)
(59400 - 63720 @ 2160), (N/A, 44), (N/A)
(63720 - 65880 @ 2160), (N/A, 28), (N/A)

and all the channels above 100 are marked as disabled in iw list
output (after the plug not before) for the alfa card

It is as if the TL-WN722N has CN reg dom hard-coded and that switches
it globally to CN too ???

Is this a bug in ath9k_htc ? a bug with the TL-WN722N card ??