linux-kernel - Re: [PATCH net-next v4 00/23] net: add EEE support for KSZ9477 and AR8035 with i.MX6

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Date:   Sat, 4 Feb 2023 02:13:32 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Wei Fang <wei.fang@....com>,
        Heiner Kallweit <hkallweit1@...il.com>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Arun.Ramadoss@...rochip.com, intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH net-next v4 00/23] net: add EEE support for KSZ9477 and
 AR8035 with i.MX6

On Wed, Feb 01, 2023 at 03:58:22PM +0100, Oleksij Rempel wrote:
> With this patch series we provide EEE control for KSZ9477 family of switches and
> AR8035 with i.MX6 configuration.
> According to my tests, on a system with KSZ8563 switch and 100Mbit idle link,
> we consume 0,192W less power per port if EEE is enabled.

What is the code flow through the kernel with EEE? I wasn't able to find
a good explanation about it.

Is it advertised by default, if supported? I guess phy_advertise_supported()
does that.

But is that desirable? Doesn't EEE cause undesired latency for MAC-level
PTP timestamping on an otherwise idle link?