Re: [PATCH 0/3] net: renesas: rswitch: R-Car S4 add HW offloading for layer 2 switching

[Nikita Yushchenko <nikita.yoush@cogentembedded.com>]

04.07.2025 19:53, Andrew Lunn wrote:
> On Fri, Jul 04, 2025 at 11:05:14AM +0200, Nikita Yushchenko wrote:
>>> Looking at the code, it is not clear to me what would happen with:
>>>
>>> ip link add name br0 type bridge
>>> ip link set dev tsn0 master br0
>>> ip link set dev br0 up
>>> ip link set dev tsn0 up
>>> ip link add name br1 type bridge
>>> ip link set dev tsn1 master br1
>>> ip link set dev br1 up
>>> ip link set dev tsn1 up
>>
>> Per design, it shall enable hardware forwarding when two ports are in the same brdev.
> 
> So in this case, the hardware offload has been reserved by br0, but is
> in fact never used, since there is only one port in the bridge. If i
> was to then do
> 
> ip link set dev tsn2 master br1
> ip link set dev tsn2 up
> 
> br1 would not be offloaded, but done in software.

rswitch_update_offload_brdev() calculates which brdev to offload, and it only considers brdev having at 
least two rswitch ports. So in this case br1 shall get offloaded.

Nikita