linux-kernel - Re: [PATCH net 5/6] net: hns3: fix wrong print link down up

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Message-ID: <2c6514a7-db97-f345-9bc4-affd4eba2dda@huawei.com>
Date:   Sat, 29 Jul 2023 11:11:48 +0800
From:   Jijie Shao <shaojijie@...wei.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <yisen.zhuang@...wei.com>, <salil.mehta@...wei.com>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <shenjian15@...wei.com>,
        <wangjie125@...wei.com>, <liuyonglong@...wei.com>,
        <wangpeiyang1@...wei.com>, <netdev@...r.kernel.org>,
        <stable@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net 5/6] net: hns3: fix wrong print link down up

Hi Andrew,
I understand what you mean, and sorry for my wrong description. The link
is not always up. If I turn auto-neg off, the link will go down finally.
However, there is an intervel between my operation and the link down. In
my experiment, it may be 1 min or evn 10 mins. The phy state is set to
PHY_UP immediately when I set auto-neg off. And the phy machine check the
state during a very small intervals. Thus, during my experiment, the phy
state has a followed varietion:
PHY_RUNNING -> PHY_UP -> PHY_RUNNING -> PHY_NOLINK.

We print link up/down based on phy state and link state. In aboved case,
It print looks like:
eth0 link down -- because phy state is set to PHY_UP
eth0 link up -- because phy state is set to PHY_RUNNING
eth0 link down -- because link down

This patch wants to fix the first two wrong print.
We will modify this patch description

Thanks!

   Jijie Shao

on 2023/7/28 16:57, Andrew Lunn wrote:
> On Fri, Jul 28, 2023 at 03:58:39PM +0800, Jijie Shao wrote:
>> From: Peiyang Wang <wangpeiyang1@...wei.com>
>>
>> This patch will fix a wrong print "device link down/up". Consider a case
>> that set autoneg to off with same speed and duplex configuration. The link
>> is always up while the phy state is set to PHY_UP and set back to
>> PHY_RUNNING later. It will print link down when the phy state is not
>> PHY_RUNNING. To avoid that, the condition should include PHY_UP.
> Does this really happen? If autoneg is on, and there is link, it means
> the link peer is auto using auto-neg. If you turn auto-neg off, the
> link peer is not going to know what speed to use, and so the link will
> go down. The link will only come up again when you reconfigure the
> link peer to also not use auto-neg.
>
> I don't see how you can turn auto-neg off and not loose the link.
>
>    Andrew