From: Luke Howard <lukeh@padl.com>
To: Cedric Jehasse <cedric.jehasse@gmail.com>
Cc: cedric.jehasse@luminex.be, Andrew Lunn <andrew@lunn.ch>,
Vladimir Oltean <olteanv@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
Russell King <linux@armlinux.org.uk>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Christoph Mellauner <christoph.mellauner@joyned.at>,
Kieran Tyrrell <kieran@sienda.com>
Subject: Re: [PATCH net-next 2/2] net: dsa: mv88e6xxx: add support for credit based shaper
Date: Fri, 19 Jun 2026 15:00:12 +1000 [thread overview]
Message-ID: <A3A6C8D7-3B6D-4716-88C7-EC32DB9D087D@padl.com> (raw)
In-Reply-To: <CABvLYuBZ=U96gVpYqHnnhwBZxp8OZzH-W503MsbNd4JPqLbEpQ@mail.gmail.com>
> On 28 May 2026, at 7:19 pm, Cedric Jehasse <cedric.jehasse@gmail.com> wrote:
>
> On Thu, May 28, 2026 at 1:52 AM Luke Howard <lukeh@padl.com> wrote:
>> Would also be good to add support for the 6341, which as 4 queues but uses the same Qav multipliers as the 6390.
> I'll have a look at the 6341
As an aside, the 6341 driver is buggy. It assumes the chip does not have a dedicated ATU FID register because it has 256 databases. This is incorrect and breaks VLAN-aware bridging. I will post a patch when the merge window reopens.
On the hardware side, the ATU hashing algorithm appears to easily collide. This causes problems with things such as installing the broadcast address into multiple FIDs, not to mention 802.1Q Dynamic Reservation Entries. The only workaround is to use the ‘direct’ algorithm which may have a performance impact (I am presuming it is a linear search; the data sheet warns against using it).
Luke
next prev parent reply other threads:[~2026-06-19 5:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-22 10:56 [PATCH net-next 0/2] " Cedric Jehasse via B4 Relay
2026-05-22 10:56 ` [PATCH net-next 1/2] net: dsa: mv88e6xxx: use the hw tx queues Cedric Jehasse via B4 Relay
2026-05-25 9:26 ` Marek Behún
2026-05-26 8:57 ` Cedric Jehasse
2026-05-26 12:13 ` Andrew Lunn
2026-05-26 13:15 ` Paolo Abeni
2026-05-22 10:56 ` [PATCH net-next 2/2] net: dsa: mv88e6xxx: add support for credit based shaper Cedric Jehasse via B4 Relay
2026-05-26 0:32 ` Luke Howard
2026-05-26 5:37 ` Luke Howard
2026-05-26 11:28 ` Cedric Jehasse
2026-05-26 12:35 ` Luke Howard
2026-05-28 0:17 ` Luke Howard
2026-05-28 8:11 ` Cedric Jehasse
2026-05-28 10:15 ` Luke Howard
2026-05-28 12:46 ` Andrew Lunn
2026-05-28 23:13 ` Luke Howard
2026-05-26 13:15 ` Paolo Abeni
2026-05-27 23:52 ` Luke Howard
2026-05-28 9:19 ` Cedric Jehasse
2026-05-28 9:49 ` Luke Howard
2026-06-19 5:00 ` Luke Howard [this message]
2026-06-19 5:59 ` Andrew Lunn
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