Re: [PATCH net-next 00/10] net: airoha: Support multiple net_devices connected to the same GDM port

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> Hi.

Hi Ben,

> 
> On 29/03/2026 15:07, Lorenzo Bianconi wrote:
> > EN7581 or AN7583 SoCs support connecting multiple external SerDes (e.g.
> > Ethernet or USB SerDes) to GDM3 or GDM4 ports via a hw multiplexer that
> > manages the traffic in a TDM manner.
> 
> I think the word for this is arbiter. I think the common use of mux is as a
> more fixed data path selector.


ack, I will fix it in v2.

Regards,
Lorenzo

> 
> > As a result multiple net_devices can
> > connect to the same GDM{3,4} port and there is a theoretical "1:n"
> > relation between GDM ports and net_devices.
> >
> >             ┌─────────────────────────────────┐
> >             │                                 │    ┌──────┐
> >             │                         P1 GDM1 ├────►MT7530│
> >             │                                 │    └──────┘
> >             │                                 │      ETH0 (DSA conduit)
> >             │                                 │
> >             │              PSE/FE             │
> >             │                                 │
> >             │                                 │
> >             │                                 │    ┌─────┐
> >             │                         P0 CDM1 ├────►QDMA0│
> >             │  P4                     P9 GDM4 │    └─────┘
> >             └──┬─────────────────────────┬────┘
> >                │                         │
> >             ┌──▼──┐                 ┌────▼────┐
> >             │ PPE │                 │   MUX   │
> >             └─────┘                 └─┬─────┬─┘
> >                                       │     │
> >                                    ┌──▼──┐┌─▼───┐
> >                                    │ ETH ││ USB │
> >                                    └─────┘└─────┘
> >                                     ETH1   ETH2
> 
> A more representative picture is like the following and in the GDM2 path
> there is a real mux present(not relevant for this patch series though). Thus
> I think it is important to have the distinction between mux and arbiter.
> (Feel free to reuse the following illustration freely).
> 
>                 ┌─────────────────────────────────┐
>                 │                                 │    ┌──────┐
>    ┌─────────┐  │                         P1 GDM1 ├────►MT7530│
>    │   MUX   ├──│ P2 GDM2                         │    └──────┘
>    └─┬─────┬─┘  │                                 │      ETH0 (DSA conduit)
>      │     │    │                                 │
>   ┌──▼──┐┌─▼───┐│              PSE/FE             │
>   │ PON ││ PON ││                                 │
>   └─────┘└─────┘│                                 │
>    ETH5   XPON  │                                 │    ┌─────┐
>                 │                         P0 CDM1 ├────►QDMA0│
>                 │  P4      P3 GDM3        P9 GDM4 │    └─────┘
>                 └──┬──────────┬──────────────┬────┘
>                    │          │              │
>                 ┌──▼──┐  ┌────▼────┐    ┌────▼────┐
>                 │ PPE │  │   ARB   │    │   ARB   │
>                 └─────┘  └─┬─────┬─┘    └─┬─────┬─┘
>                            │     │        │     │
>                         ┌──▼──┐┌─▼───┐ ┌──▼──┐┌─▼───┐
>                         │PCIE0││PCIE1│ │ ETH ││ USB │
>                         └─────┘└─────┘ └─────┘└─────┘
>                           ETH3   ETH4    ETH1   ETH2
> 
> MvH
> Benjamin Larsson

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