PRI4 revision a03111 bluetooth problems

I've can't seem to get bluetooth working on my RPI4. This is the version information from cpuinfo:

Code:Hardware : BCM2711
Revision : a03111
Serial : 1000000091328354
Model : Raspberry Pi 4 Model B Rev 1.1I'm running SlackwareARM 14.2 with sarpi kernel for current ... not the latest (5.10.11 at the time of writing) because that won't boot right on my device. I'm actually using kernel 5.4.40.

I keep on getting this message in the kernel ring buffer:
Code:brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.txt failed with error -2I've tried several firmware files from:
sarpi4-hacks-4.0-armv7l-1_slackcurrent_28Jan21_sp1.txz
borrowed from raspbian
https://github.com/RPi-Distro/firmwa...ee/master/brcm

None seem to work (all produce the same message in kernel ring buffer) and hciconfig shows no bluetooth device.
Wifi seems to be working fine but I wanted have the bluetooth working for testing for something I plan to do in the near future.

Has anyone got similar problems ?
Anyone know how to solve it ?