Comment # 5 on bug 1195857 from Takashi Iwai

Thanks.

Unfortunately, I couldn't spot the possible fix through a quick glance between
5.16.2 and 5.16.4.  There haven't been any changes in brcmfmac driver itself,
for example, and PCI change doesn't seem related.

The best we can do for now is to identify the breakage via git bisection.
You'd need to build the kernel, install and test it by yourself.  As the range
is relatively narrow (between 5.16.2 and 5.16.4), it would be relatively
straightforward.  Also, you can reduce the kernel config at first via "make
localmodconfig", which helps a lot for kernel build time reduction.

In nutshell, the step is something like below:
- Install git, kernel-tools, gcc, bc, libelf-devel, bison, flex,
libopenssl-devel packages.
- Clone linux-stable git tree
  % git clone
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
- Check out v5.16.2
  % cd linux-stable
  % git checkout v5.16.2
- Create a reduced kernel config via "make localmodconfig"
  % make localmodconfig
  Then edit .config file, modify CONFIG_LOCALVERSION to "-test", for example.
- Build it
  % make -j8
- Install it
  % sudo make install

Then you can boot and test with it.  The v5.16.2 should be the working kernel.
After confirming it's working, check out v5.16.4.
  % cd linux-stable
  % git checkout v5.16.4
Modify CONFIG_LOCALVERSION again to another suffix for avoiding conflicts.
Then make, install and test with it.
If v5.16.4 is confirmed to show the expected problem, then start bisection.

  % git bisect start
  % git bisect good v5.16.2
  % git bisect bad v5.16.4
This will lead you to the point to test.  Again, modify CONFIG_LOCALVERSION to
a new suffix "e.g. bisect-1", build, install and test.
If the tested kernel is OK, run "git bisect good", otherwise "git bisect bad".
Repeat the step until it reaches to the culprit commit.