No WLAN channel 12/13

[Alexander Wetzel]

We can’t scan channel 12 an 13 with the RED board
Why could this be?

We use the actual Debian

OSD32MP1-RED-trusted-debian-sdcard-v1_2

It’s set to DE
# iw reg get
global
country DE: DFS-ETSI
(2400 – 2483 @ 40), (N/A, 20), (N/A)
(5150 – 5250 @ 80), (N/A, 20), (N/A), NO-OUTDOOR, AUTO-BW
(5250 – 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
(5470 – 5725 @ 160), (N/A, 26), (0 ms), DFS
(5725 – 5875 @ 80), (N/A, 13), (N/A)
(57000 – 66000 @ 2160), (N/A, 40), (N/A)

The frequency should be usable
# iw list |grep MHz
* 2412 MHz [1] (20.0 dBm)
* 2417 MHz [2] (20.0 dBm)
* 2422 MHz [3] (20.0 dBm)
* 2427 MHz [4] (20.0 dBm)
* 2432 MHz [5] (20.0 dBm)
* 2437 MHz [6] (20.0 dBm)
* 2442 MHz [7] (20.0 dBm)
* 2447 MHz [8] (20.0 dBm)
* 2452 MHz [9] (20.0 dBm)
* 2457 MHz [10] (20.0 dBm)
* 2462 MHz [11] (20.0 dBm)
* 2467 MHz [12] (20.0 dBm)
* 2472 MHz [13] (20.0 dBm)
* 2484 MHz [14] (disabled)

there is no AP with chennel 11 listed
# iw dev wlan0 scan | egrep “freq:|signal:|SSID:” | sed -e “s/\tfreq: //” -e “s/\tsignal: //” -e “s/\tSSID: //” | awk ‘{ORS = (NR % 3 == 0)? “\n” : ” “; print}’ | sort
2412 -53.00 dBm VisionDevices
2412 -84.00 dBm CelenoInitialAP9F180F
2412 -85.00 dBm FRITZ!Box Gastzugang
2412 -88.00 dBm FRITZ!Box Gastzugang
2437 -83.00 dBm
2437 -83.00 dBm WLAN-Gross
2437 -83.00 dBm WLAN-Gross
2462 -67.00 dBm VisionDevices

[Erik Welsh]

This is most likely due to the firmware being loaded as part of the BRCM driver for the WiFi module. By default, channels 12 and 13 are not allowed in North America (https://en.wikipedia.org/wiki/List_of_WLAN_channels#2.4_GHz_(802.11b/g/n/ax)). In the default device tree, we do not specify any country codes for the BRCM driver: https://github.com/octavosystems/OSD32MP1-RED-Device-tree/blob/main/linux-v5.10-r0/stm32mp157c-osd32mp1-red.dts#L1286 Therefore, the driver most likely defaults to loading the firmware for North America since not using channels 12 and 13 is ok everywhere in the world even if they are available. If you look at the device tree bindings for the BRCM driver: https://www.kernel.org/doc/Documentation/devicetree/bindings/net/wireless/brcm%2Cbcm4329-fmac.yaml you can see that there is a “brcm,ccode-map” attribute that can be set. Try setting this parameter appropriately for your country and see if that fixes the problem.

Thanks,
Erik

[Author]

Posts