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

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Message-ID:
 <TYRPR01MB14284CB75C7DCD35381BD17EE8299A@TYRPR01MB14284.jpnprd01.prod.outlook.com>
Date: Thu, 5 Feb 2026 13:46:39 +0000
From: Michael Dege <michael.dege@...esas.com>
To: Nikita Yushchenko <nikita.yoush@...entembedded.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

Hello Nikita,

> -----Original Message-----
> From: Nikita Yushchenko <nikita.yoush@...entembedded.com>
> Sent: Thursday, February 5, 2026 2:39 PM
> 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; linux-renesas-soc@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH net] net: renesas: rswitch: fix forwarding offload statemachine
> 
> >>> if (rdev_for_l2_offload() && rdev->forwarding_requested)
> >>>       rswitch_change_l2_hw_offloading(rdev, true, false); else
> >>>       rswitch_change_l2_hw_offloading(rdev, false, false);
> >>>
> >>> since rswitch_change_l2_hw_offloading() has internal check for the
> >>> current state and returns early if the requested change is already applied.
> >
> > Unfortunately, this has a side effect, e.g., if you pull the cable on
> > tsn0 and the link goes down, you will see that the offloading is
> > disabled on all ports connected to the bridge and not just on tsn0.
> 
> Quite strange, is anything else logged?  E.g. some messages from linux bridge layer?
> 
> Nikita

Here is the log from the version without "if else"

[   83.107759] renesas_eth_sw e6880000.ethernet tsn0: Link is Down
[   83.108734] br0: port 1(tsn0) entered disabled state
[   83.109669] renesas_eth_sw e6880000.ethernet tsn0: stopping hw learning
[   83.110519] renesas_eth_sw e6880000.ethernet tsn0: stopping hw forwarding
[   83.111405] renesas_eth_sw e6880000.ethernet tsn1: stopping hw forwarding
[   91.299976] renesas_eth_sw e6880000.ethernet tsn0: Link is Up - 1Gbps/Full - flow control off
[   91.357634] br0: port 1(tsn0) entered blocking state
[   91.358309] br0: port 1(tsn0) entered forwarding state
[   91.359185] renesas_eth_sw e6880000.ethernet tsn1: starting hw forwarding
[   91.360104] renesas_eth_sw e6880000.ethernet tsn0: starting hw learning
[   91.360943] renesas_eth_sw e6880000.ethernet tsn0: starting hw forwarding
[   91.361802] renesas_eth_sw e6880000.ethernet tsn1: stopping hw forwarding

And this is what it should look like:

[   81.027632] renesas_eth_sw e6880000.ethernet tsn0: Link is Down
[   81.028662] br0: port 1(tsn0) entered disabled state
[   81.029582] renesas_eth_sw e6880000.ethernet tsn0: stopping hw learning
[   81.030431] renesas_eth_sw e6880000.ethernet tsn0: stopping hw forwarding
[   90.243832] renesas_eth_sw e6880000.ethernet tsn0: Link is Up - 1Gbps/Full - flow control off
[   90.305291] br0: port 1(tsn0) entered blocking state
[   90.305956] br0: port 1(tsn0) entered forwarding state
[   90.306838] renesas_eth_sw e6880000.ethernet tsn0: starting hw learning
[   90.307725] renesas_eth_sw e6880000.ethernet tsn0: starting hw forwarding

Best regards

Michael