linux-kernel - Re: [RFC net-next Patch 0/3] net: bridge: mrp: Add support for Media Redundancy Protocol(MRP)

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Date:   Fri, 10 Jan 2020 18:56:08 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
Cc:     Vladimir Oltean <olteanv@...il.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        lkml <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        bridge@...ts.linux-foundation.org,
        "David S. Miller" <davem@...emloft.net>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        anirudh.venkataramanan@...el.com, David Ahern <dsahern@...il.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>
Subject: Re: [RFC net-next Patch 0/3] net: bridge: mrp: Add support for Media
 Redundancy Protocol(MRP)

> > Horatiu, could you also give some references to the frames that need
> > to be sent. I've no idea what information they need to contain, if the
> > contents is dynamic, or static, etc.
> It is dynamic - but trivial...

If it is trivial, i don't see why you are so worried about abstracting
it?

> Here is a dump from WireShark with
> annotation on what our HW can update:
> 
> Ethernet II, Src: 7a:8b:b1:35:96:e1 (7a:8b:b1:35:96:e1), Dst: Iec_00:00:01 (01:15:4e:00:00:01)
>     Destination: Iec_00:00:01 (01:15:4e:00:00:01)
>     Source: 7a:8b:b1:35:96:e1 (7a:8b:b1:35:96:e1)
>     Type: MRP (0x88e3)
> PROFINET MRP MRP_Test, MRP_Common, MRP_End
>     MRP_Version: 1
>     MRP_TLVHeader.Type: MRP_Test (0x02)
>         MRP_TLVHeader.Type: MRP_Test (0x02)
>         MRP_TLVHeader.Length: 18
>         MRP_Prio: 0x1f40 High priorities
>         MRP_SA: 7a:8b:b1:35:96:e1 (7a:8b:b1:35:96:e1)
>         MRP_PortRole: Primary ring port (0x0000)
>         MRP_RingState: Ring closed (0x0001)
>         MRP_Transition: 0x0001
>         MRP_TimeStamp [ms]: 0x000cf574             <---------- Updated automatic
>     MRP_TLVHeader.Type: MRP_Common (0x01)
>         MRP_TLVHeader.Type: MRP_Common (0x01)
>         MRP_TLVHeader.Length: 18
>         MRP_SequenceID: 0x00e9                     <---------- Updated automatic
>         MRP_DomainUUID: ffffffff-ffff-ffff-ffff-ffffffffffff
>     MRP_TLVHeader.Type: MRP_End (0x00)
>         MRP_TLVHeader.Type: MRP_End (0x00)
>         MRP_TLVHeader.Length: 0
> 
> But all the fields can change, but to change the other fields we need to
> interact with the HW. Other SoC may have other capabilities in their
> offload. As an example, if the ring becomes open then the fields
> MRP_RingState and MRP_Transition need to change and in our case this
> requires SW interference.

Isn't SW always required? You need to tell your state machine that the
state has changed.

> Would you like a PCAP file as an example? Or do you want a better
> description of the frame format.

I was hoping for a link to an RFC, or some standards document.

  Andrew