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SubjectRe: [RFC PATCH 0/1] net: phy: skip autoneg of ethernet(fec) on network boot
From
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?


From: Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: [RFC PATCH 0/1] net: phy: skip autoneg of ethernet(fec) on
network boot
Date: Fri, 6 Jul 2018 11:41:23 -0700

>
>
> On 07/05/2018 11:07 PM, Masahiko Kimoto wrote:
> > Hello,
> >
> > This patch introduces auto negotiation skipping for Ethernet.
> > It is useful to shorten boot time on network boot like the following
> > environment;
> >
> > - target board is NXP i.MX6.
> > - NIC is fec.
> > - using u-boot as boot loader.
> > - boot from kernel and initramfs obtained via TFTP.
> > - mount remote file system and switch root to that.
> > - thus all file system is on network.
> >
> > In this case, u-boot and kernel initialize NIC three times,
> > once in boot loader, once in device attach and once more in phy attach.
> > Each causes link auto negotiation and wait several seconds.
> > However link state is stable after reset by boot loader, therefore we
> > can skip hardware re-initialization of NIC in kernel.
> >
> > The patch skips link down in Ethernet(i.MX's fec) driver and initialization
> > in PHY layer if kernel option 'anegskip' is supplied.
> >
> > By this patch boot time becomes 3secs shorter.
> >
> > I think current patch is dirty hack, because;
> > - modification is split into PHY and Ethernet driver.
> > - in the case of two or more Ethernet I/F exist, currently there is
> > no way to specify whith I/F skips autonego.
> >
> > I would like to implement such skpping auto negotiation feature in generic
> > framework. How should we implement these requirements?
>
> 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
> --
> Florian
>

---------------------------------------------------------------------------
Masahiko KIMOTO,Ph.D. / Cybertrust Japan Co., Ltd.
mail: masahiko.kimoto@cybertrust.co.jp
web: https://www.cybertrust.co.jp/ https://www.miraclelinux.com/

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