Comment # 5 on bug 1177256 from Stefan Dirsch

I don't know the standard search pasth for firmware files. If it is 

  /lib/firmware/$(uname -r)
  /lib/firmware

it's obvious that things break once you update the kernel. In this case the
driver packages installed the firmware files to  

  /lib/firmware/5.3.18-lp152.36-default

these then even get installed to initrd, but kernel kernel
5.3.18-lp152.41-default now is looking for them in

  /lib/firmware/ 5.3.18-lp152.41-default

???

Takashi, do you happen to know the search paths for firmware files?