RPI bwfm: checksum error

[Luke Ross <luke%lukeross.name@localhost>]

Hi,

Regarding the built-in broadcom wifi on Raspberry Pi boards, the bwfm
driver connects reliably and for light use behaves fine. Initiating
large transfers tends to hang the wifi, with the kernel logging bursts
of:

bwfm0: checksum error

Once it happens, the wifi sometimes recovers but much of the time the
only way to recover connectivity is to reboot the pi. It doesn't seem
to be affected (either way) by whether the bluetooth is also running.
The rest of the kernel continues to run fine.

Weirdly, likelihood of hitting this seems to vary depending on the
application initiating the transfer - fetching a large file over https
tends to die after about 10MB, whilst an scp transfer of 100MB or so
frequently works fine (albeit with quite long pauses). Frustratingly,
using pkgin to install/update packages seems to be the quickest way to
wedge the wifi for me.

I've found both the 0W and the 3A+ (slightly different wifi chip model)
exhibit the same error. It's been this way for me for quite a while, up
to and including a run with HEAD build 202103121650Z (earmv6hf) today.
I've seen the issue mentioned on this list in the past, but there
didn't seem to be an obvious conclusion.

Are there any easy solutions to this? For example, do different
firmwares or configurations work better? Is it a widely-known issue, or
should I file a problem report so it can be tracked? I had a quick look
through gnats but didn't seen anything about this error.

Many thanks,

Luke