netdev - Re: [PATCH net-next v2 0/3] ethtool: support for forward error correction mode setting on a link

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Date:   Thu, 27 Jul 2017 19:33:20 -0700
From:   Jakub Kicinski <kubakici@...pl>
To:     Roopa Prabhu <roopa@...ulusnetworks.com>
Cc:     davem@...emloft.net, linville@...driver.com,
        netdev@...r.kernel.org, vidya.chowdary@...il.com,
        dustin@...ulusnetworks.com, olson@...ulusnetworks.com,
        leedom@...lsio.com, galp@...lanox.com, andrew@...n.ch,
        manojmalviya@...lsio.com, santosh@...lsio.com,
        yuval.mintz@...gic.com, odedw@...lanox.com, ariela@...lanox.com,
        jeffrey.t.kirsher@...el.com
Subject: Re: [PATCH net-next v2 0/3] ethtool: support for forward error
 correction mode setting on a link

On Thu, 27 Jul 2017 16:47:25 -0700, Roopa Prabhu wrote:
> From: Roopa Prabhu <roopa@...ulusnetworks.com>
> 
> Forward Error Correction (FEC) modes i.e Base-R
> and Reed-Solomon modes are introduced in 25G/40G/100G standards
> for providing good BER at high speeds. Various networking devices
> which support 25G/40G/100G provides ability to manage supported FEC
> modes and the lack of FEC encoding control and reporting today is a
> source for interoperability issues for many vendors.
> FEC capability as well as specific FEC mode i.e. Base-R
> or RS modes can be requested or advertised through bits D44:47 of base link
> codeword.
> 
> This patch set intends to provide option under ethtool to manage and
> report FEC encoding settings for networking devices as per IEEE 802.3
> bj, bm and by specs.
> 
> v2 :
>         - minor patch format fixes and typos pointed out by Andrew
>         - there was a pending discussion on the use of 'auto' vs
>           'automatic' for fec settings. I have left it as 'auto'
>           because in most cases today auto is used in place of
>           automatic to represent automatically generated values.
>           We use it in other networking config too. I would prefer
>           leaving it as auto.

On the subject of resetting the values when module is replugged I
assume what was previously described remains:
 - we always allow users to set the FEC regardless of the module type;
 - if user set an incorrect FEC for the module type (or module gets
   swapped) the link will be administratively taken down by either
   the driver or FW.

Is that correct?  Am I misremembering?