[SOLVED] Weird wireless issues on APU

[NC1]

I've got my grubby hands on two old APUs (I believe they are both APU1). Installed a Qualcomm Atheros QCA986x/988x NIC into each (with hostapd, ath10k-firmware-qca988x, and kmod-ath10k to support them). Initially, everything ran great. Then, I noticed something strange.

On a cold boot (or on halt-unplug-replug), the wireless card appears to be ignored. dmesg | grep wlan returns nothing. ip a lists the loopback, three wired interfaces, and br-lan, but no wlan.

On a warm reboot (reboot), meanwhile, things work out differently. The wireless card is reliably detected and initialized. dmesg reports as expected:

root@APU1:~# dmesg | grep wlan
[   21.060364] br-lan: port 3(wlan0) entered blocking state
[   21.065804] br-lan: port 3(wlan0) entered disabled state
[   21.071441] device wlan0 entered promiscuous mode
[   29.658799] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   29.665440] br-lan: port 3(wlan0) entered blocking state
[   29.670812] br-lan: port 3(wlan0) entered forwarding state

There's a little quirk in the ip a output though:

root@APU1:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP qlen 1000
    link/ether 00:0d:b9:40:15:cc brd ff:ff:ff:ff:ff:ff
    inet 10.42.0.133/24 brd 10.42.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20d:b9ff:fe40:15cc/64 scope link 
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br-lan state UP qlen 1000
    link/ether 00:0d:b9:40:15:cd brd ff:ff:ff:ff:ff:ff
4: eth2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel master br-lan state DOWN qlen 1000
    link/ether 00:0d:b9:40:15:ce brd ff:ff:ff:ff:ff:ff
6: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    link/ether 00:0d:b9:40:15:cd brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.1/24 brd 192.168.1.255 scope global br-lan
       valid_lft forever preferred_lft forever
    inet6 fd55:5136:72bf::1/60 scope global noprefixroute 
       valid_lft forever preferred_lft forever
    inet6 fe80::20d:b9ff:fe40:15cd/64 scope link 
       valid_lft forever preferred_lft forever
7: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-lan state UP qlen 1000
    link/ether 7c:5a:1c:85:1c:3b brd ff:ff:ff:ff:ff:ff
    inet6 fe80::7e5a:1cff:fe85:1c3b/64 scope link 
       valid_lft forever preferred_lft forever

Note that there is no number 5 in the listing; it goes from 4 straight to 6. Not sure if this is significant.

When the device is running normally, lspci reports the Wi-Fi card as:

04:00.0 Network controller [0280]: Qualcomm Atheros QCA986x/988x 802.11ac Wireless Network Adapter [168c:003c]

In the "weird mode", the same lspci reports the same Wi-Fi card differently:

04:00.0 Ethernet controller [0200]: Qualcomm Atheros Device [168c:abcd] (rev 01)

All of the above is observed on two devices, one running 22.03.5 / x64 / ext4 / bios, the other running 22.03.5 / x64 / squashfs / bios.

If anyone has any ideas, I'm all ears...

[NC1]

Problem tentatively solved by relocating the Wi-Fi card from the slot marked mPCIe 1 on the motherboard to the slot marked mPCIe 2, or, in terms of the image below, from the rightmost slot to the middle slot.