linux-kernel - Re: [RFC] net: phy: read link status twice when phy_check_link

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Message-ID: <1d4be6ad-ffe6-2325-ceab-9f35da617ee9@huawei.com>
Date:   Tue, 30 Jul 2019 12:03:49 +0800
From:   liuyonglong <liuyonglong@...wei.com>
To:     Heiner Kallweit <hkallweit1@...il.com>, <andrew@...n.ch>,
        <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <salil.mehta@...wei.com>,
        <yisen.zhuang@...wei.com>, <shiju.jose@...wei.com>
Subject: Re: [RFC] net: phy: read link status twice when
 phy_check_link_status()



On 2019/7/30 4:57, Heiner Kallweit wrote:
> On 29.07.2019 05:59, liuyonglong wrote:
>>
>>
>> On 2019/7/27 2:14, Heiner Kallweit wrote:
>>> On 26.07.2019 11:53, Yonglong Liu wrote:
>>>> According to the datasheet of Marvell phy and Realtek phy, the
>>>> copper link status should read twice, or it may get a fake link
>>>> up status, and cause up->down->up at the first time when link up.
>>>> This happens more oftem at Realtek phy.
>>>>
>>> This is not correct, there is no fake link up status.
>>> Read the comment in genphy_update_link, only link-down events
>>> are latched. Means if the first read returns link up, then there
>>> is no need for a second read. And in polling mode we don't do a
>>> second read because we want to detect also short link drops.
>>>
>>> It would be helpful if you could describe your actual problem
>>> and whether you use polling or interrupt mode.
>>>
>>
>> [   44.498633] hns3 0000:bd:00.1 eth5: net open
>> [   44.504273] hns3 0000:bd:00.1: reg=0x1, data=0x79ad -> called from phy_start_aneg
>> [   44.532348] hns3 0000:bd:00.1: reg=0x1, data=0x798d -> called from phy_state_machine,update link.
> 
> This should not happen. The PHY indicates link up w/o having aneg finished.
> 
>>
>> According to the datasheet:
>> reg 1.5=0 now, means copper auto-negotiation not complete
>> reg 1.2=1 now, means link is up
>>
>> We can see that, when we read the link up, the auto-negotiation
>> is not complete yet, so the speed is invalid.
>>
>> I don't know why this happen, maybe this state is keep from bios?
>> Or we may do something else in the phy initialize to fix it?
>> And also confuse that why read twice can fix it?
>>
> I suppose that basically any delay would do.
> 
>> [   44.554063] hns3 0000:bd:00.1: invalid speed (-1)
>> [   44.560412] hns3 0000:bd:00.1 eth5: failed to adjust link.
>> [   45.194870] hns3 0000:bd:00.1 eth5: link up
>> [   45.574095] hns3 0000:bd:00.1: phyid=3, reg=0x1, data=0x7989
>> [   46.150051] hns3 0000:bd:00.1 eth5: link down
>> [   46.598074] hns3 0000:bd:00.1: phyid=3, reg=0x1, data=0x7989
>> [   47.622075] hns3 0000:bd:00.1: phyid=3, reg=0x1, data=0x79a9
>> [   48.646077] hns3 0000:bd:00.1: phyid=3, reg=0x1, data=0x79ad
>> [   48.934050] hns3 0000:bd:00.1 eth5: link up
>> [   49.702140] hns3 0000:bd:00.1: phyid=3, reg=0x1, data=0x79ad
>>
>>>> I add a fake status read, and can solve this problem.
>>>>
>>>> I also see that in genphy_update_link(), had delete the fake
>>>> read in polling mode, so I don't know whether my solution is
>>>> correct.
>>>>
> 
> Can you test whether the following fixes the issue for you?
> Also it would be interesting which exact PHY models you tested
> and whether you built the respective PHY drivers or whether you
> rely on the genphy driver. Best use the second patch to get the
> needed info. It may make sense anyway to add the call to
> phy_attached_info() to the hns3 driver.
> 

[   40.100716] RTL8211F Gigabit Ethernet mii-0000:bd:00.3:07: attached PHY driver [RTL8211F Gigabit Ethernet] (mii_bus:phy_addr=mii-0000:bd:00.3:07, irq=POLL)
[   40.932133] hns3 0000:bd:00.3 eth7: net open
[   40.932458] hns3 0000:bd:00.3: invalid speed (-1)
[   40.932541] 8021q: adding VLAN 0 to HW filter on device eth7
[   40.937149] hns3 0000:bd:00.3 eth7: failed to adjust link.

[   40.662050] Generic PHY mii-0000:bd:00.2:05: attached PHY driver [Generic PHY] (mii_bus:phy_addr=mii-0000:bd:00.2:05, irq=POLL)
[   41.563511] hns3 0000:bd:00.2 eth6: net open
[   41.563853] hns3 0000:bd:00.2: invalid speed (-1)
[   41.563943] 8021q: adding VLAN 0 to HW filter on device eth6
[   41.568578] IPv6: ADDRCONF(NETDEV_CHANGE): eth6: link becomes ready
[   41.568898] hns3 0000:bd:00.2 eth6: failed to adjust link.

I am using RTL8211F, but you can see that, both genphy driver and
RTL8211F driver have the same issue.

> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 6b5cb87f3..fbecfe210 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1807,7 +1807,8 @@ int genphy_read_status(struct phy_device *phydev)
>  
>  	linkmode_zero(phydev->lp_advertising);
>  
> -	if (phydev->autoneg == AUTONEG_ENABLE && phydev->autoneg_complete) {
> +	if (phydev->autoneg == AUTONEG_ENABLE &&
> +	    (phydev->autoneg_complete || phydev->link)) {
>  		if (phydev->is_gigabit_capable) {
>  			lpagb = phy_read(phydev, MII_STAT1000);
>  			if (lpagb < 0)
> 

I have try this patch, have no effect. I suppose that at this time,
the autoneg actually not complete yet.

Maybe the wrong phy state is passed from bios? Invalid speed just
happen at the first time when ethX up, after that, repeat the
ifconfig down/ifconfig up command can not see that again.

So I think the bios should power off the phy(writing reg 1.11 to 1)
before it starts the OS? Or any other way to fix this in the OS?