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

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Message-ID: <20170624214742.GO4875@lunn.ch>
Date:   Sat, 24 Jun 2017 23:47:42 +0200
From:   Andrew Lunn <andrew@...n.ch>
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, manojmalviya@...lsio.com, santosh@...lsio.com,
        yuval.mintz@...gic.com, odedw@...lanox.com, ariela@...lanox.com,
        galp@...lanox.com, jeffrey.t.kirsher@...el.com
Subject: Re: [PATCH net-next 0/3] ethtool: support for forward error
 correction mode setting on a link

On Sat, Jun 24, 2017 at 12:19:42PM -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 itneroperability issues for many vendors.

interoperability. The same typ0 exists in the first patch

> 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.

For my own education, is this logically a MAC or a PHY thing?  Is the
negotiation performed at the PHY level, and then FEC happens at the
MAC level?

I'm just trying to look ahead when we start getting 25G/40G/100G PHY
support. Does phylib need an extension, similar to how pause is
negotiated at the PHY, and then the MAC does the actual work?

	 Andrew