Arch Linux

Description:

My wifi unexpectedly stopped working. It is an *Intel Corporation Cannon Point-LP CNVi [Wireless-AC] [8086:9df0] (rev 30)* and I'm on *linux 5.4.2* kernel.

The network interface `wlo1` also keeps appearing and disappearing from `ip link show`. I tried
* setting the interface up with `ip link` after blocking and unblocking with rfkill, but the problem persists and I get `RTNETLINK answers: Input/output error`.
* disabling network manager and connecting via wpa_supplicant, but I also get these I/O errors and the interface appearing and disappearing.

Some error messages related to `iwlwifi` appear on dmesg (you can find the full output in the attachment):
```
[ 1129.745754] iwlwifi 0000:00:14.3: Firmware not running - cannot dump error
[ 1130.135378] iwlwifi 0000:00:14.3: Microcode SW error detected. Restarting 0x0.
[ 1130.135488] iwlwifi 0000:00:14.3: Start IWL Error Log Dump:
[ 1130.135608] iwlwifi 0000:00:14.3: Start IWL Error Log Dump:
[ 1130.135670] iwlwifi 0000:00:14.3: 0x249F90BC | FSEQ_ERROR_CODE
[ 1130.135808] iwlwifi 0000:00:14.3: Firmware error during reconfiguration - reprobe!
[ 1130.135833] iwlwifi 0000:00:14.3: FW error in SYNC CMD SCAN_CFG_CMD
[ 1130.524526] iwlwifi 0000:00:14.3: Microcode SW error detected. Restarting 0x0.
[ 1130.524622] iwlwifi 0000:00:14.3: Start IWL Error Log Dump:
[ 1130.524760] iwlwifi 0000:00:14.3: Start IWL Error Log Dump:
[ 1130.524827] iwlwifi 0000:00:14.3: 0x249F90BC | FSEQ_ERROR_CODE
[ 1130.525059] iwlwifi 0000:00:14.3: FW error in SYNC CMD SCAN_CFG_CMD
```

Still, my wifi works fine when running puppy linux on a USB flash drive (Ubuntu-based kernel 4.9).

I've been following some threads on older kernel versions that had (apparently/almost) the same problem with the very same driver.
* #63117: seems to have been solved in kernel 5.2.2, but only when downgrading `linux-firmware` to patch `20190618.acb56f2-1`. The error, however, appears to be other: `FW error in SYNC CMD GEO_TX_POWER_LIMIT`. Moreover, I did try downgrading linux-firmware (archive + makepkg), but it did not work for me on kernel 5.4.2
* #63967: I'm also having this restart problem (see `dmesg` output). It is said this was solved in linux kernel `5.3.5-arch1-1`
* #64112: says it has been solved in kernel `5.3.10-arch1-1`.
* #64262: same as #64112

Additional info:
* It stopped working on Dec 3rd 2019, everything was fine in November :)
* file `details.txt` attached with some info:
* kernel version: 5.4.2-arch1-1 (`uname` and `pacman -Q linux`)
* linux firmware patch: 20191118.e8a0f4c-2 (`pacman -Qi linux-firmware`)
* kernel drivers handling PCI Network card: Intel Corporation Cannon Point-LP CNVi [Wireless-AC] (rev 30) (`lspci -k`)
* kernel ring buffer (focus on iwlwifi): `dmesg`

Steps to reproduce:
* having a network card from Intel
* linux kernel 5.4.2
* linux-firmware 20191118.e8a0f4c-2