[Bug 2013027] Re: Issues over broadcom brcmfmac43455 firmware

[Sergio Callegari]

I have diagnosed the problem as follows.

My broadcom 43455 adapter needs:

1. a different brcm43455-sdio.txt file from the one supplied in ubuntu,
which is a cypress provided version.

2. a different brcm43455-sdio.bin file from the one supplied in ubuntu,
that again is a cypress provided version

3. a different brcm43455-sdio.clm_blob file from the one supplied in
ubuntu


Now, 1 and 2 are no issue: I can supply the files needed by my hardware and put them side to side to the ubuntu supplied ones. This is because the system will seek `brcm43455-sdio.AZW-Z83 II.{txt, bin} first.
Incidentally, the txt file can be easily taken from the nvram of my system, while the bin file is the one that is supplied in armbian, libreelec etc, that for some reason is not the same as the cypress one found in ubuntu.

The real problem is 3. And this is because without the file made for my
hardware, the wifi will work in the 2.4 GHz band, but not in the 5GHz
band. However the file name for this does not appear to be adapted to my
system. Namely, if I put a 'brcm43455-sdio.AZW-Z83 II.clm_blob' file
side to side to 'brcm43455-sdio.clm_blob' that will be ignored.

This makes it impossible to place board specific brcm files *side to
side* the those currently specified by the distro (unless I miss
something). If this is the case, then there are two possible
workarounds:

1. Make a deb file with a diversion for the clm_blob file
2. Use the brcmfmac module option `alternative_fw_path` to specify and alternative firmware path for my brcm hardware and put my bin, txt and clm_blob files there

However, I really tend to think that these are just ugly workarounds for
what is ultimately an issue with the brcmfmac kernel module. If the
module can determine that for by board the filename should be
`brcm43455-sdio.AZW-Z83 II.{txt,bin}` for the txt and bin pieces of the
firmware, then why cannot it look at `brcm43455-sdio.AZW-Z83
II.clm_blob` before falling back to `brcm43455-sdio.clm_blob`? That
would make it easy to put different firmwares in the the brcm firmware
directory side by side and make the framework that is already there for
the txt and bin files actually useful.

Please consider reopening the issue, passing it to the brcmfmac
maintainers.

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https://bugs.launchpad.net/bugs/2013027

Title:
  Issues over broadcom brcmfmac43455 firmware

Status in linux-firmware package in Ubuntu:
  Incomplete
Status in linux-firmware-raspi2 package in Ubuntu:
  Invalid

Bug description:
  Hi, I have a Kodlix Z83-II minicomputer that employs a broadcom
  chipset for WIFI.

  The only way to make wifi on that PC work is to use the firmware from
  the windows image, even if that chipset is apparently managed in
  ubuntu.

  With the firmware files provided by ubuntu you get no 5GHz for wifi.
  The problem is that every time ubuntu updates the firmware package,
  firmware files dropped in /lib/firmware get overwritten, linking to
  some file in the cypress sub-directory.

  - Ideally, Ubuntu should provide all the firmware files that might be
  needed. Maybe this is not possible as there is a too large variety of
  different firmwares for broadcom chipsets or licesing issues
  preventing distribution.

  - As a second possibility, there should be a way to drop files in
  /lib/firmware 'side to side' to the distro ones, without having the
  risk of finding the manually added files rewritten. This implies that
  different pieces of hardware use firmware files with different
  filenames. Don't know if this is truly possible, as I do not know how
  the linux kernel decides the name of the firmware to load.

  - In cases like mine, it seems that the ubuntu firmware package puts
  in place symlinks to have brcmfmac43455 files point to the
  corresponding cypress cyfmac43455 files. Possibly, the package could
  avoid creating the symlinks if a brcmfmac43455 file is manually placed
  in lib/firmware.

  - As a last resort, I think that the documentation in
  `/usr/share/doc/linux-firmware` should be augmented to describe the
  most appropriate way to prevent custom firmware files from being
  rewritten: marking files not-writable? introducing diversions?

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