net: stmmac: dwmac-meson8b: interface sometimes does not come up at boot

[Erico Nunes]

On Sat, Feb 26, 2022 at 2:53 PM Heiner Kallweit <hkallweit1 at gmail.com> wrote:
> Just to rule out that the PHY may be involved:
> - Does the issue occur with internal and/or external PHY?

My target boards have the internal phy only. It is not possible for me
at the moment to test it with an external phy.

> - Issue still occurs in PHY polling mode? (disable PHY interrupt in dts)

Thanks for suggesting this. I did tests with this and it seems to be a
workaround.
With phy interrupt on recent kernels (around v5.17-rc3) I'm able to
reproduce the issue relatively easily over a batch of a hundred jobs.
With my tests with the phy in polling mode, I have not been able to
reproduce so far, even with several hundred jobs.

For completeness I also tested 46f69ded988d (from my initial analysis)
and setting the phy to polling mode there does not make a difference,
issue still reproduces. So it may have been a different bug. Though I
guess at this point we can disregard that and focus on the current
kernel.

I tried adding a few debugs and delays to the interrupt code path in
drivers/net/phy/meson-gxl.c but nothing gave me useful info so far.

Do you have more advice on how to proceed from here?

Thanks

Erico