Re: [PATCH net-next v5 4/4] phy: aquantia: Determine rate adaptation support from registers

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Sean Anderson <sean.anderson@seco.com>
Cc: Vladimir Oltean <olteanv@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
	Paolo Abeni <pabeni@redhat.com>,
	linux-kernel@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Tim Harvey <tharvey@gateworks.com>
Subject: Re: [PATCH net-next v5 4/4] phy: aquantia: Determine rate adaptation support from registers
Date: Thu, 5 Jan 2023 19:06:17 +0000	[thread overview]
Message-ID: <Y7cfqdVzrCNX6VqE@shell.armlinux.org.uk> (raw)
In-Reply-To: <18453c4e-484d-5131-36fe-77d3e55d6ac7@seco.com>

On Thu, Jan 05, 2023 at 01:59:27PM -0500, Sean Anderson wrote:
> On 1/5/23 13:55, Russell King (Oracle) wrote:
> > On Thu, Jan 05, 2023 at 07:52:06PM +0200, Vladimir Oltean wrote:
> >> On Thu, Jan 05, 2023 at 12:43:47PM -0500, Sean Anderson wrote:
> >> > Again, this is to comply with the existing API assumptions. The current
> >> > code is buggy. Of course, another way around this is to modify the API.
> >> > I have chosen this route because I don't have a situation like you
> >> > described. But if support for that is important to you, I encourage you
> >> > to refactor things.
> >> 
> >> I don't think I'm aware of a practical situation like that either.
> >> I remember seeing some S32G boards with Aquantia PHYs which use 2500BASE-X
> >> for 2.5G and SGMII for <=1G, but that's about it in terms of protocol switching.
> > 
> > 88x3310 can dynamically switch between 10GBASE-R, 5GBASE-R, 2500BASE-X
> > and SGMII if rate adaption is not being used (and the rate adaption
> > method it supports in non-MACSEC PHYs is only via increasing the IPG on
> > the MAC... which currently no MAC driver supports.)
> > 
> 
> As an aside, do you know of any MACs which support open-loop rate
> matching to below ~95% of the line rate (the amount necessary for
> 10GBASE-W)?

I'm afraid I haven't paid too much attention to BASE-W, and I'm not
aware of anything within the realms of phylink/phylib supporting MAC
drivers having anything for it. I don't even remember mention of it
in any SoC datasheets.

Are you aware of a 10GBASE-W setup?

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