netdev - Re: [RFC PATCH 0/1] net: phy: skip autoneg of ethernet(fec) on network boot

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Message-ID: <20180709144106.GJ10376@lunn.ch>
Date:   Mon, 9 Jul 2018 16:41:06 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Masahiko KIMOTO <masahiko.kimoto@...ertrust.co.jp>
Cc:     f.fainelli@...il.com, fugang.duan@....com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, hiraku.toyooka@...ertrust.co.jp
Subject: Re: [RFC PATCH 0/1] net: phy: skip autoneg of ethernet(fec) on
 network boot

On Mon, Jul 09, 2018 at 06:29:02PM +0900, Masahiko KIMOTO wrote:
> Hello Florian,
> 
>   > I completely acknowledge and support the use case, but your
>   > implementation is definitively not the way to go. In my experience the
>   > problem is usually that there may be a disagreement on the
>   > Pause/Asym_Pause advertisement bits and that alone is responsible for
>   > triggering a re-negotiation. Can yo check if that is the case here?
> 
> Thank you for your support.
> 
> Concening the problem about PAUSE/Asym_PAUSE advertisement you pointed out,
> I could not understand your consideration.
> 
> Would you tell me more detail about it?

Hi Masahiko

You said that the PHY is being configured 3 times, and might be doing
auto-neg three times. Often a phy will not actually perform auto-neg,
or do it much faster, if the advertised bits do not change with each
re-configuration.

So check how u-boot is configuring what is advertised, and look at
what Linux is configuring. In particularly, look at the pause
configuration. If pause is configured different in u-boot and Linux,
try to make it the same. Things might go faster than.

    Andrew