Re: [PATCH net-next 2/2] net: dsa: mv88e6xxx: use direct ATU hash on 88E6141/6341

[Luke Howard]

> On 4 Jul 2026, at 1:40 am, Andrew Lunn <andrew@xxxxxxx> wrote:
> 
> On Fri, Jul 03, 2026 at 04:42:56PM +1000, Luke Howard wrote:
>> The default 88E6341/88E6141 ATU hash algorithm appears to result
>> in frequent collisions, evicting permanent registrations (including
>> the broadcast address) out of the ATU.
> 
> Is there any documentation about how the 88E6341/88E6141 hashing
> algorithm is different to all the other chips? How is it special?

No documentation, just my experience, which is why I asked in the cover for others to test. I can include test results with the next revision.

>> have a performance impact (the data sheet notes this is for testing
>> only), but it also enables correctness, at least in local testing.
> 
> How do you define correctness? Are you using a well defined test?
> 
> Why is the devlink parameter not sufficient.

Devlink would indeed be better, but changing hash mode with a non-empty ATU causes it to be corrupt on read back. Perhaps the right solution is to flus the ATU when changing hash mode via devlink.

Luke