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Date: Mon, 12 Aug 2019 12:49:50 +0800
From: Yonglong Liu <liuyonglong@...wei.com>
To: Heiner Kallweit <hkallweit1@...il.com>,
Andrew Lunn <andrew@...n.ch>
CC: <davem@...emloft.net>, <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 2019/8/10 4:05, Heiner Kallweit wrote:
> On 09.08.2019 06:57, Yonglong Liu wrote:
>>
>>
>> On 2019/8/9 4:34, Andrew Lunn wrote:
>>> On Thu, Aug 08, 2019 at 10:01:39PM +0200, Heiner Kallweit wrote:
>>>> On 08.08.2019 21:40, Andrew Lunn wrote:
>>>>>> @@ -568,6 +568,11 @@ int phy_start_aneg(struct phy_device *phydev)
>>>>>> if (err < 0)
>>>>>> goto out_unlock;
>>>>>>
>>>>>> + /* The PHY may not yet have cleared aneg-completed and link-up bit
>>>>>> + * w/o this delay when the following read is done.
>>>>>> + */
>>>>>> + usleep_range(1000, 2000);
>>>>>> +
>>>>>
>>>>> Hi Heiner
>>>>>
>>>>> Does 802.3 C22 say anything about this?
>>>>>
>>>> C22 says:
>>>> "The Auto-Negotiation process shall be restarted by setting bit 0.9 to a logic one. This bit is self-
>>>> clearing, and a PHY shall return a value of one in bit 0.9 until the Auto-Negotiation process has been
>>>> initiated."
>>>>
>>>> Maybe we should read bit 0.9 in genphy_update_link() after having read BMSR and report
>>>> aneg-complete and link-up as false (no matter of their current value) if 0.9 is set.
>>>
>>> Yes. That sounds sensible.
>>>
>>> Andrew
>>>
>>> .
>>>
>>
>> Hi Heiner:
>> I have test more than 50 times, it works. Previously less
>> than 20 times must be recurrence. so I think this patch solved the
>> problem.
>> And I checked about 40 times of the time gap between read
>> and autoneg started, all of them is more than 2ms, as below:
>>
>> kworker/u257:1-670 [015] .... 27.182632: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x00 val:0x1240
>> kworker/u257:1-670 [015] .... 27.184670: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x7989
>>
>>
>
> Instead of using this fixed delay, the following experimental patch
> considers that fact that between triggering aneg start and actual
> start of aneg (incl. clearing aneg-complete bit) Clause 22 requires
> a PHY to keep bit 0.9 (aneg restart) set.
> Could you please test this instead of the fixed-delay patch?
>
> Thanks, Heiner
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index b039632de..163295dbc 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1741,7 +1741,17 @@ EXPORT_SYMBOL(genphy_aneg_done);
> */
> int genphy_update_link(struct phy_device *phydev)
> {
> - int status;
> + int status = 0, bmcr;
> +
> + bmcr = phy_read(phydev, MII_BMCR);
> + if (bmcr < 0)
> + return bmcr;
> +
> + /* Autoneg is being started, therefore disregard BMSR value and
> + * report link as down.
> + */
> + if (bmcr & BMCR_ANRESTART)
> + goto done;
>
> /* The link state is latched low so that momentary link
> * drops can be detected. Do not double-read the status
>
Hi Heiner:
Have test 50+ times, this patch can solved the problem too!
Share the mdio trace after executing ifconfig ethx up:
# tracer: nop
#
# entries-in-buffer/entries-written: 60/60 #P:128
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
ifconfig-1174 [005] .... 27.026691: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:1-670 [020] .... 27.026734: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x04 val:0x01e1
kworker/u257:1-670 [020] .... 27.026744: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x04 val:0x05e1
kworker/u257:1-670 [020] .... 27.026799: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79ad
kworker/u257:1-670 [020] .... 27.026834: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x09 val:0x0200
kworker/u257:1-670 [020] .... 27.026869: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:1-670 [020] .... 27.026879: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x00 val:0x1240
kworker/u257:1-670 [020] .... 27.026932: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1240
kworker/u257:1-670 [020] .... 28.031770: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:1-670 [020] .... 28.031837: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x7989
kworker/u257:1-670 [020] .... 29.055837: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:1-670 [020] .... 29.055873: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x7989
kworker/u257:0-8 [004] .... 30.079840: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:0-8 [004] .... 30.079875: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x7989
kworker/u257:0-8 [004] .... 31.103771: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:0-8 [004] .... 31.103839: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79a9
kworker/u257:0-8 [004] .... 31.103906: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x0a val:0x7803
kworker/u257:0-8 [004] .... 31.103973: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x09 val:0x0200
kworker/u257:0-8 [004] .... 31.104041: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x05 val:0xc1e1
kworker/u257:0-8 [004] .... 32.127814: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:0-8 [004] .... 32.127881: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79ad
kworker/u257:0-8 [004] .... 32.127948: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x0a val:0x4800
kworker/u257:0-8 [004] .... 32.128015: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x09 val:0x0200
kworker/u257:0-8 [004] .... 32.128082: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x05 val:0xc1e1
kworker/u257:0-8 [004] .... 33.151775: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:0-8 [004] .... 33.151815: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79ad
kworker/u257:1-670 [021] .... 34.175771: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
kworker/u257:1-670 [021] .... 34.175838: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79ad
ifconfig-1177 [005] .... 35.052340: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
ifconfig-1177 [005] .... 35.052350: mdio_access: mii-0000:bd:00.3 write phy:0x07 reg:0x00 val:0x1840
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