netdev - Re: [PATCH net] net: phy: rtl8211f: do a double read to get real time link status

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Date:   Thu, 8 Aug 2019 09:15:00 +0800
From:   Yonglong Liu <liuyonglong@...wei.com>
To:     Heiner Kallweit <hkallweit1@...il.com>, <davem@...emloft.net>,
        <andrew@...n.ch>
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: [PATCH net] net: phy: rtl8211f: do a double read to get real time
 link status



On 2019/8/8 0:47, Heiner Kallweit wrote:
> On 07.08.2019 15:16, Yonglong Liu wrote:
>> [   27.232781] hns3 0000:bd:00.3 eth7: net open
>> [   27.237303] 8021q: adding VLAN 0 to HW filter on device eth7
>> [   27.242972] IPv6: ADDRCONF(NETDEV_CHANGE): eth7: link becomes ready
>> [   27.244449] hns3 0000:bd:00.3: invalid speed (-1)
>> [   27.253904] hns3 0000:bd:00.3 eth7: failed to adjust link.
>> [   27.259379] RTL8211F Gigabit Ethernet mii-0000:bd:00.3:07: PHY state change UP -> RUNNING
>> [   27.924903] hns3 0000:bd:00.3 eth7: link up
>> [   28.280479] RTL8211F Gigabit Ethernet mii-0000:bd:00.3:07: PHY state change RUNNING -> NOLINK
>> [   29.208452] hns3 0000:bd:00.3 eth7: link down
>> [   32.376745] RTL8211F Gigabit Ethernet mii-0000:bd:00.3:07: PHY state change NOLINK -> RUNNING
>> [   33.208448] hns3 0000:bd:00.3 eth7: link up
>> [   35.253821] hns3 0000:bd:00.3 eth7: net stop
>> [   35.258270] hns3 0000:bd:00.3 eth7: link down
>>
>> When using rtl8211f in polling mode, may get a invalid speed,
>> because of reading a fake link up and autoneg complete status
>> immediately after starting autoneg:
>>
>>         ifconfig-1176  [007] ....    27.232763: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x00 val:0x1040
>>   kworker/u257:1-670   [015] ....    27.232805: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x04 val:0x01e1
>>   kworker/u257:1-670   [015] ....    27.232815: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x04 val:0x05e1
>>   kworker/u257:1-670   [015] ....    27.232869: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x01 val:0x79ad
>>   kworker/u257:1-670   [015] ....    27.232904: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x09 val:0x0200
>>   kworker/u257:1-670   [015] ....    27.232940: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x00 val:0x1040
>>   kworker/u257:1-670   [015] ....    27.232949: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x00 val:0x1240
>>   kworker/u257:1-670   [015] ....    27.233003: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x01 val:0x79ad
>>   kworker/u257:1-670   [015] ....    27.233039: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x0a val:0x3002
>>   kworker/u257:1-670   [015] ....    27.233074: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x09 val:0x0200
>>   kworker/u257:1-670   [015] ....    27.233110: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x05 val:0x0000
>>   kworker/u257:1-670   [000] ....    28.280475: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x01 val:0x7989
>>   kworker/u257:1-670   [000] ....    29.304471: mdio_access: mii-0000:bd:00.3 read  phy:0x07 reg:0x01 val:0x7989
>>
>> According to the datasheet of rtl8211f, to get the real time
>> link status, need to read MII_BMSR twice.
>>
>> This patch add a read_status hook for rtl8211f, and do a fake
>> phy_read before genphy_read_status(), so that can get real link
>> status in genphy_read_status().
>>
>> Signed-off-by: Yonglong Liu <liuyonglong@...wei.com>
>> ---
>>  drivers/net/phy/realtek.c | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>>
> Is this an accidental resubmit? Because we discussed this in
> https://marc.info/?t=156413509900003&r=1&w=2 and a fix has
> been applied already.
> 
> Heiner
> 
> .
> 

In https://marc.info/?t=156413509900003&r=1&w=2 , the invalid speed
recurrence rate is almost 100%, and I had test the solution about
5 times and it works. But yesterday it happen again suddenly, and than
I fount that the recurrence rate reduce to 10%. This time we get 0x79ad
after autoneg started which is not 0x798d from last discussion.