linux-kernel - Re: [PATCH net] net: renesas: rswitch: fix forwarding offload statemachine

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Message-ID: <a4cfeba2-23da-4fdd-870b-6533b5ce267c@cogentembedded.com>
Date: Thu, 5 Feb 2026 15:41:17 +0100
From: Nikita Yushchenko <nikita.yoush@...entembedded.com>
To: Michael Dege <michael.dege@...esas.com>,
 Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
 "linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] net: renesas: rswitch: fix forwarding offload
 statemachine

>> The driver was originally designed to enable hardware forwarding when not less than two ports are in
>> forwarding state. When only one port has hw forwarding, there is no destination to forward.
>>
>> Nikita
>>
> 
> The current driver allows Linux to use the bridge port as local port to the bridge. The offloading
> Also supports switching traffic to Linux through the bridge port. Therefore, the offloading shouldn't
> Be dropped if only one external port is up on the bridge.

"Offloading" means - forward a frame from one hw port to other hw port without inserting it into CPU 
queue. Offloaded frame is never visible to software bridge.

There is code that allows offload only if the linux bridge device used to connect rswitch ports does not 
have anything else.  If it has something else, offloading is disabled (because there is no way to know 
when a frame can be processed within rswitch hw without sending it to cpu).

Nikita