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

[Heiner Kallweit]

On 20.02.2022 17:51, Erico Nunes wrote:
> On Mon, Feb 7, 2022 at 11:56 AM Jerome Brunet <jbrunet at baylibre.com> wrote:
>>
>>
>> On Wed 02 Feb 2022 at 21:18, Erico Nunes <nunes.erico at gmail.com> wrote:
>>
>>> Hello,
>>>
>>> I've been tracking down an issue with network interfaces from
>>> meson8b-dwmac sometimes not coming up properly at boot.
>>> The target systems are AML-S805X-CC boards (Amlogic S805X SoC), I have
>>> a group of them as part of a CI test farm that uses nfsroot.
>>>
>>> After hopefully ruling out potential platform/firmware and network
>>> issues I managed to bisect this commit in the kernel to make a big
>>> difference:
>>>
>>>   46f69ded988d2311e3be2e4c3898fc0edd7e6c5a net: stmmac: Use resolved
>>> link config in mac_link_up()
>>>
>>> With a kernel before that commit, I am able to submit hundreds of test
>>> jobs and the boards always start the network interface properly.
>>>
>>> After that commit, around 30% of the jobs start hitting this:
>>>
>>>   [    2.178078] meson8b-dwmac c9410000.ethernet eth0: PHY
>>> [0.e40908ff:08] driver [Meson GXL Internal PHY] (irq=48)
>>>   [    2.183505] meson8b-dwmac c9410000.ethernet eth0: Register
>>> MEM_TYPE_PAGE_POOL RxQ-0
>>>   [    2.200784] meson8b-dwmac c9410000.ethernet eth0: No Safety
>>> Features support found
>>>   [    2.202713] meson8b-dwmac c9410000.ethernet eth0: PTP not supported by HW
>>>   [    2.209825] meson8b-dwmac c9410000.ethernet eth0: configuring for
>>> phy/rmii link mode
>>>   [    3.762108] meson8b-dwmac c9410000.ethernet eth0: Link is Up -
>>> 100Mbps/Full - flow control off
>>>   [    3.783162] Sending DHCP requests ...... timed out!
>>>   [   93.680402] meson8b-dwmac c9410000.ethernet eth0: Link is Down
>>>   [   93.685712] IP-Config: Retrying forever (NFS root)...
>>>   [   93.756540] meson8b-dwmac c9410000.ethernet eth0: PHY
>>> [0.e40908ff:08] driver [Meson GXL Internal PHY] (irq=48)
>>>   [   93.763266] meson8b-dwmac c9410000.ethernet eth0: Register
>>> MEM_TYPE_PAGE_POOL RxQ-0
>>>   [   93.779340] meson8b-dwmac c9410000.ethernet eth0: No Safety
>>> Features support found
>>>   [   93.781336] meson8b-dwmac c9410000.ethernet eth0: PTP not supported by HW
>>>   [   93.788088] meson8b-dwmac c9410000.ethernet eth0: configuring for
>>> phy/rmii link mode
>>>   [   93.807459] random: fast init done
>>>   [   95.353076] meson8b-dwmac c9410000.ethernet eth0: Link is Up -
>>> 100Mbps/Full - flow control off
>>>
>>> This still happens with a kernel from master, currently 5.17-rc2 (less
>>> frequently but still often hit by CI test jobs).
>>> The jobs still usually get to work after restarting the interface a
>>> couple of times, but sometimes it takes 3-4 attempts.
>>>
>>> Here is one example and full dmesg:
>>> https://gitlab.freedesktop.org/enunes/mesa/-/jobs/16452399/raw
>>>
>>> Note that DHCP does not seem to be an issue here, besides the fact
>>> that the problem only happens since the mentioned commit under the
>>> same setup, I did try to set up the boards to use a static ip but then
>>> the interfaces just don't communicate at all from boot.
>>>
>>> For test purposes I attempted to revert
>>> 46f69ded988d2311e3be2e4c3898fc0edd7e6c5a on top of master but that
>>> does not apply trivially anymore, and by trying to revert it manually
>>> I haven't been able to get a working interface.
>>>
>>> Any advice on how to further debug or fix this?
>>
>> Hi Erico,
>>
>> Thanks a lot for digging into this topic.
>> I'm seeing exactly the same behavior on the g12 based khadas-vim3:
>>
>> * Boot stalled waiting for DHCP - with an NFS based filesystem
>> * Every minute, the network driver gets a reset and try again
>>
>> Sometimes it works on the first attempt, sometimes it takes up to 5
>> attempts. Eventually, it reaches the prompt which might be why it went
>> unnoticed so far.
>>
>> I think that NFS just makes the problem easier to see.
>> On devices with an eMMC based filesystem, I noticed that, sometimes, I
>> had unplug/plug the ethernet cable to make it go.
>>
>> So far, the problem is reported on all the Amlogic SoC generation we
>> support. I think a way forward is to ask the the other users of
>> stmmac whether they have this problem or not - adding Allwinner and
>> Rockchip ML.
>>
>> Since the commit you have identified is in the generic part of the
>> stmmac code, Maybe Jose can help us understand what is going on.
> 
> Hi all,
> 
> thanks for the feedback so far, good to know that this is not only on
> my board farm.
> 
> Any more feedback about this from the people in cc?
> 
> Thanks
> 
> Erico

Just to rule out that the PHY may be involved:
- Does the issue occur with internal and/or external PHY?
- Issue still occurs in PHY polling mode? (disable PHY interrupt in dts)