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

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Message-ID: <150d8d95-a6cd-dc28-618b-6cc5295b4bf9@huawei.com>
Date:   Tue, 17 Oct 2023 21:03:01 +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


on 2023/7/31 17:10, Jijie Shao wrote:
>
> on 2023/7/30 2:23, Andrew Lunn wrote:
>>>      Now i wounder if you are fixing the wrong thing. Maybe you 
>>> should be
>>>      fixing the PHY so it does not report up and then down? You say 
>>> 'very
>>>      snall intervals', which should in fact be 1 second. So is the PHY
>>>      reporting link for a number of poll intervals? 1min to 10 minutes?
>>>
>>>                Andrew
>>>
>>> Yes, according to the log records, the phy polls every second,
>>> but the link status changes take time.
>>> Generally, it takes 10 seconds for the phy to detect link down,
>>> but occasionally it takes several minutes to detect link down,
>> What PHY driver is this?
>>
>> It is not so clear what should actually happen with auto-neg turned
>> off. With it on, and the link going down, the PHY should react after
>> about 1 second. It is not supposed to react faster than that, although
>> some PHYs allow fast link down notification to be configured.
>>
>> Have you checked 802.3 to see what it says about auto-neg off and link
>> down detection?
>>
>> I personally would not suppress this behaviour in the MAC
>> driver. Otherwise you are going to have funny combinations of special
>> cases of a feature which very few people actually use, making your
>> maintenance costs higher.
>>
>>         Andrew

Hi Andrew,
We've rewritten the commit log to explain this problem,
Would you please take some time to review that?

The following is the new commit log:
This patch is to correct a wrong log info "link down/up" in hns3 driver.
When setting autoneg off without changing speed and duplex, the link
should be not changed. However in hns3 driver, it print link down/up once
incorrectly. We trace the phy machine state and find the phy change form
PHY_UP to PHY_RUNNING. No other state of PHY occurs during this process.
MDIO trace also indicate the link is on. The wrong log info and mdio
trace are showed as followed:

[  843.720783][  T367] hns3 0000:35:00.0 eth1: set link(phy): autoneg=0,
speed=10, duplex=1
[  843.736087][  T367] hns3 0000:35:00.0 eth1: link down
[  843.773506][   T17] RTL8211F Gigabit Ethernet mii-0000:35:00.0:02: PHY
state change UP -> RUNNING
[  844.674668][   T31] hns3 0000:35:00.0 eth1: link up

      kworker/1:1-32      [001] ....   841.457231: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x79ad
      kworker/1:1-32      [001] ....   842.486496: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x79ad
      kworker/1:1-32      [001] ....   843.520565: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x79ad
      kworker/0:1-17      [000] ....   843.757147: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x798d
      kworker/0:1-17      [000] ....   844.799141: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x798d
      kworker/0:1-17      [000] ....   845.831513: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x798d
      kworker/0:1-17      [000] ....   846.863053: mdio_access: mii-0000:
35:00.0 read  phy:0x02 reg:0x01 val:0x798d

Regards
Jijie