Network functionality in v2020.04 on Raspberry Pi 4

[Harald Seiler]

Hello Sasha,

adding Matthias Brugger on Cc as he is the maintainer for Raspberry Pi.

On Thu, 2020-04-16 at 20:25 +0000, Jevtic, Sasha wrote:
> Hello all,
> 
> I am encountering considerable difficulty with the networking
> functionality on Raspberry Pi 4 on the latest release (2020.04).  In
> particular, I have observed:
> 
>     * any network operation that fails renders networking functionality
>       inoperable until reboot.
>     * ping always fails.
>     * TFTP download attempt of non-existent file fails (resulting in
>       subsequent network operations failing).
>     * TFTP download of an existing file usually works, but occasionally
>       experiences timeouts during transfers; some are timeouts are
>       intermittent (the transfer ultimately resumes), and some are
>       permanent.
>     * TFTP download of a script usually works (as above). The script
>       will run, but any additional TFTP downloads performed by a script
>       all fail.
> 
> It is not entirely clear right now whether this is a problem in U-Boot
> (i.e., instead of in the execution environment set up by the Raspberry
> Pi firmware), but the TFTP infrastructure I am using is known to work
> well with other hardware running an older version of U-Boot.  Also,
> there are also no network issues in the Linux environment that
> I ultimately boot, so hardware also seems unlikely.  Thus, suggestions
> for things to check would be appreciated; I am of course also happy to
> provide any supporting data required to investigate.

If you have know which older version still worked, you can use
git-bisect [1] to find out where the regression was introduced.  Ideally,
if you can automate installation of a newly built U-Boot version, this can
run entirely unattended to find out where the bug was introduced.

[1]: https://git-scm.com/docs/git-bisect

> Please also be aware that I initially posted a very similar inquiry to
> the Raspberry Pi Forum:
> 
> https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=271068
> 
> Thanks.
> 
> Sasha
-- 
Harald