On 24/01/2025 22:15, Hauke Mehrtens wrote:
@arinc9:
Currently we have the following known bugs:
[...]
* Ethernet link unstable on some mt7530 switches. Deactivate EEE
(Energy-Efficient Ethernet) as a workaround, see:
https://github.com/openwrt/openwrt/issues/17351
Any idea what could be going on there?
Here are the facts to consider:
We have only started receiving reports of the unstable link issue with the
24.10 branch.
I believe the MT753X DSA subdriver did not receive changes in years with
regards to EEE or any other parts of the code that would cause link
instability. I am giving this opinion as a maintainer of the said
subdriver.
There's a report by Florian [1], stating that the same issue appears with a
PHY that is not part of the MT7530 switch hardware. So the issue is
apparent on a system that does not have the MT7530 switch involved, and the
only common part of the reports is the MediaTek Ethernet driver.
What I deduce from this is, a recent change in the MediaTek Ethernet driver
is causing issues with the operation of EEE. Disabling EEE resolves the
issue but does not address the cause. That is why I have stated on the
GitHub issue linked above that I am going to refrain from disabling EEE by
default on MT7530 for the time being.
I do not maintain the MediaTek Ethernet driver so it is out of my
jurisdiction.
Someone told me that EEE is not activated for all mt7530 switches. Before it
was only activated on some boards. It looks like it is broken on some boards.
We should probably deactivate it by default again like it was in 23.05.
Hauke, this doesn't make sense to me. My findings [2] show that EEE has
been enabled on MT7530 as long as the support for it was brought to the
MT753X DSA subdriver. If anybody has findings that claim otherwise AND runs
into the unstable link issue on pre-24.10 firmware, let me know; we can
disable EEE on the DSA subdriver instead, which will actually disable it
for all boards. For example, EEE for MT7531 is disabled on the MT753X DSA
subdriver.
With that said, you are free to do your own hacks on the
OpenWrt-bastardised Linux to make things work. However, I will have none of
that on mainline. So I don't want to see any patches submitted for the
drivers that I maintain, that don't address the cause of the issue. I am
not open to discuss this.
[1] https://github.com/openwrt/openwrt/issues/17351#issuecomment-2608342255
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=af3b4b0e59decfc4db2eafbb4e0d0658529019f6
Chester A.
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