Date: Wed, 13 Apr 2022 10:22:15 +0100
From: Andrew Preater <alpine@preater.com>
To: ~alpine/users@lists.alpinelinux.org
Subject: Some 5 GHz wifi channels not working / disabled on Raspberry Pi 4
Message-ID: <YlaWR29yOPJi3s7F@preater.com>
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Dear Alpiners

I have installed Alpine 3.15.4 aarch64 on a Raspberry Pi 4 B rev 1.4, with
the intention to run Kodi. Other than the problem below with wifi, Alpine
is working really well with Kodi and it looks like a great fit for this
application.

I found that certain 5 GHz wifi channels are disabled in Alpine on the Pi.
Specifically, I need to be able to connect using channel 64, but this is
not possible with the channel disabled. 2.4 GHz wifi does work as expected.

I am in the UK and have country=GB set in wpa_supplicant.conf.

I decided to use sys mode for the Kodi Pi, although have duplicated the
problem in diskless install mode. I have also duplicated the issue with
32-bit armv7 Alpine.

This problem seems to be similar to the issue with 2.4 GHz channels 12-13
reported by Michal Artazov:
https://lists.alpinelinux.org/~alpine/users/%3CD5AC2D43-904F-4EE2-9FF0-DE0828D4AEF3%40signageos.io%3E

It also seems very similar to these problems reported in Manjaro and
EndeavourOS for Raspberry Pi 4:
https://forum.manjaro.org/t/raspberry-pi-4b-5ghz-upper-frequencies-disabled-tried-many-fixes/99155/1
https://forum.endeavouros.com/t/some-5-ghz-wifi-channels-are-disabled-in-raspberry-pi-4/24296

On Alpine Linux v3.15, I can see the following channels:

$ iwlist channel
lo        no frequency information.

eth0      no frequency information.

wlan0     20 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 36 : 5.18 GHz
          Channel 40 : 5.2 GHz
          Channel 44 : 5.22 GHz
          Channel 48 : 5.24 GHz
          Channel 149 : 5.745 GHz
          Channel 153 : 5.765 GHz
          Channel 157 : 5.785 GHz
          Channel 161 : 5.805 GHz
          Channel 165 : 5.825 GHz
          Current Frequency:2.412 GHz (Channel 1)

~ $ iw reg get
global
country GB: DFS-ETSI
	(2400 - 2483 @ 40), (N/A, 20), (N/A)
	(5150 - 5250 @ 80), (N/A, 23), (N/A), NO-OUTDOOR, AUTO-BW
	(5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
	(5470 - 5730 @ 160), (N/A, 26), (0 ms), DFS
	(5725 - 5850 @ 80), (N/A, 23), (N/A), NO-OUTDOOR
	(57000 - 71000 @ 2160), (N/A, 40), (N/A)

phy#0
country 99: DFS-UNSET
	(2402 - 2482 @ 40), (6, 20), (N/A)
	(2474 - 2494 @ 20), (6, 20), (N/A)
	(5140 - 5360 @ 160), (6, 20), (N/A)
	(5460 - 5860 @ 160), (6, 20), (N/A)

$ uname -a
Linux celestine.local 5.15.32-0-rpi4 #1-Alpine SMP PREEMPT Mon Mar 28 13:39:27 UTC 2022 aarch64 Linux

If I run Raspberry Pi OS (2022-04-04), based on Debian GNU/Linux 11
'bullseye' aarch64 on the same Pi, I see the following:

$ iwlist wlan0 channel
wlan0     32 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 12 : 2.467 GHz
          Channel 13 : 2.472 GHz
          Channel 34 : 5.17 GHz
          Channel 36 : 5.18 GHz
          Channel 38 : 5.19 GHz
          Channel 40 : 5.2 GHz
          Channel 42 : 5.21 GHz
          Channel 44 : 5.22 GHz
          Channel 46 : 5.23 GHz
          Channel 48 : 5.24 GHz
          Channel 52 : 5.26 GHz
          Channel 56 : 5.28 GHz
          Channel 60 : 5.3 GHz
          Channel 64 : 5.32 GHz
          Channel 100 : 5.5 GHz
          Channel 104 : 5.52 GHz
          Channel 108 : 5.54 GHz
          Channel 112 : 5.56 GHz
          Channel 116 : 5.58 GHz
          Channel 120 : 5.6 GHz
          Channel 124 : 5.62 GHz
          Current Frequency:5.32 GHz (Channel 64)

$ iw reg get
global
country GB: DFS-ETSI
	(2400 - 2483 @ 40), (N/A, 20), (N/A)
	(5150 - 5250 @ 80), (N/A, 23), (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 - 71000 @ 2160), (N/A, 40), (N/A)

phy#0
country 99: DFS-UNSET
	(2402 - 2482 @ 40), (6, 20), (N/A)
	(2474 - 2494 @ 20), (6, 20), (N/A)
	(5140 - 5360 @ 160), (6, 20), (N/A)
	(5460 - 5860 @ 160), (6, 20), (N/A)

$ uname -a
Linux raspberrypi 5.15.32-v8+ #1538 SMP PREEMPT Thu Mar 31 19:40:39 BST 2022 aarch64 GNU/Linux


With best wishes

Andrew