From: Heiner Kallweit <hkallweit1@gmail.com>
To: liuyonglong <liuyonglong@huawei.com>,
andrew@lunn.ch, davem@davemloft.net
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxarm@huawei.com, salil.mehta@huawei.com,
yisen.zhuang@huawei.com, shiju.jose@huawei.com
Subject: Re: [RFC] net: phy: read link status twice when phy_check_link_status()
Date: Tue, 30 Jul 2019 21:04:20 +0200 [thread overview]
Message-ID: <9a0a8094-42ee-0a18-0e9a-d3ca783d6d4b@gmail.com> (raw)
In-Reply-To: <03708d00-a8d9-4a9d-4188-9fe0e38de2b8@huawei.com>
On 30.07.2019 08:35, liuyonglong wrote:
> :/sys/kernel/debug/tracing$ cat trace
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 45/45 #P:128
> #
> # _-----=> irqs-off
> # / _----=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / delay
> # TASK-PID CPU# |||| TIMESTAMP FUNCTION
> # | | | |||| | |
> kworker/64:2-1028 [064] .... 172.295687: mdio_access: mii-0000:bd:00.0 read phy:0x01 reg:0x02 val:0x001c
> kworker/64:2-1028 [064] .... 172.295726: mdio_access: mii-0000:bd:00.0 read phy:0x01 reg:0x03 val:0xc916
> kworker/64:2-1028 [064] .... 172.296902: mdio_access: mii-0000:bd:00.0 read phy:0x01 reg:0x01 val:0x79ad
> kworker/64:2-1028 [064] .... 172.296938: mdio_access: mii-0000:bd:00.0 read phy:0x01 reg:0x0f val:0x2000
> kworker/64:2-1028 [064] .... 172.321213: mdio_access: mii-0000:bd:00.0 read phy:0x01 reg:0x00 val:0x1040
> kworker/64:2-1028 [064] .... 172.343209: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x02 val:0x001c
> kworker/64:2-1028 [064] .... 172.343245: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x03 val:0xc916
> kworker/64:2-1028 [064] .... 172.343882: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/64:2-1028 [064] .... 172.343918: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x0f val:0x2000
> kworker/64:2-1028 [064] .... 172.362658: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x00 val:0x1040
> kworker/64:2-1028 [064] .... 172.385961: mdio_access: mii-0000:bd:00.2 read phy:0x05 reg:0x02 val:0x001c
> kworker/64:2-1028 [064] .... 172.385996: mdio_access: mii-0000:bd:00.2 read phy:0x05 reg:0x03 val:0xc916
> kworker/64:2-1028 [064] .... 172.386646: mdio_access: mii-0000:bd:00.2 read phy:0x05 reg:0x01 val:0x79ad
> kworker/64:2-1028 [064] .... 172.386681: mdio_access: mii-0000:bd:00.2 read phy:0x05 reg:0x0f val:0x2000
> kworker/64:2-1028 [064] .... 172.411286: mdio_access: mii-0000:bd:00.2 read phy:0x05 reg:0x00 val:0x1040
> kworker/64:2-1028 [064] .... 172.433225: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x02 val:0x001c
> kworker/64:2-1028 [064] .... 172.433260: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x03 val:0xc916
> kworker/64:2-1028 [064] .... 172.433887: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x01 val:0x79ad
> kworker/64:2-1028 [064] .... 172.433922: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x0f val:0x2000
> kworker/64:2-1028 [064] .... 172.452862: mdio_access: mii-0000:bd:00.3 read phy:0x07 reg:0x00 val:0x1040
> ifconfig-1324 [011] .... 177.325585: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x00 val:0x1040
> kworker/u257:0-8 [012] .... 177.325642: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x04 val:0x01e1
> kworker/u257:0-8 [012] .... 177.325654: mdio_access: mii-0000:bd:00.1 write phy:0x03 reg:0x04 val:0x05e1
> kworker/u257:0-8 [012] .... 177.325708: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/u257:0-8 [012] .... 177.325744: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x09 val:0x0200
> kworker/u257:0-8 [012] .... 177.325779: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x00 val:0x1040
> kworker/u257:0-8 [012] .... 177.325788: mdio_access: mii-0000:bd:00.1 write phy:0x03 reg:0x00 val:0x1240
> kworker/u257:0-8 [012] .... 177.325843: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x798d
What I think that happens here:
Writing 0x1240 to BMCR starts aneg. When reading BMSR immediately after that then the PHY seems to have cleared
the "aneg complete" bit already, but not yet the "link up" bit. This results in the false "link up" notification.
The following patch is based on the fact that in case of enabled aneg we can't have a valid link if aneg isn't
finished. Could you please test whether this works for you?
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 6b5cb87f3..7ddd91df9 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1774,6 +1774,12 @@ int genphy_update_link(struct phy_device *phydev)
phydev->link = status & BMSR_LSTATUS ? 1 : 0;
phydev->autoneg_complete = status & BMSR_ANEGCOMPLETE ? 1 : 0;
+ /* Consider the case that autoneg was started and "aneg complete"
+ * bit has been reset, but "link up" bit not yet.
+ */
+ if (phydev->autoneg == AUTONEG_ENABLE && !phydev->autoneg_complete)
+ phydev->link = 0;
+
return 0;
}
EXPORT_SYMBOL(genphy_update_link);
--
2.22.0
> kworker/u257:0-8 [003] .... 178.360488: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x7989
> kworker/u257:0-8 [000] .... 179.384479: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x7989
> kworker/u257:0-8 [000] .... 180.408477: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x7989
> kworker/u257:0-8 [000] .... 181.432474: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79a9
> kworker/u257:0-8 [000] .... 181.432510: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x0a val:0x7800
> kworker/u257:0-8 [000] .... 181.432546: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x09 val:0x0200
> kworker/u257:0-8 [000] .... 181.432582: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x05 val:0xc1e1
> kworker/u257:0-8 [000] .... 182.456510: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/u257:0-8 [000] .... 182.456546: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x0a val:0x4800
> kworker/u257:0-8 [000] .... 182.456582: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x09 val:0x0200
> kworker/u257:0-8 [000] .... 182.456618: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x05 val:0xc1e1
> kworker/u257:0-8 [001] .... 183.480476: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/u257:0-8 [000] .... 184.504478: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/u257:0-8 [000] .... 185.528486: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> kworker/u257:0-8 [000] .... 186.552475: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x01 val:0x79ad
> ifconfig-1327 [011] .... 187.196036: mdio_access: mii-0000:bd:00.1 read phy:0x03 reg:0x00 val:0x1040
> ifconfig-1327 [011] .... 187.196046: mdio_access: mii-0000:bd:00.1 write phy:0x03 reg:0x00 val:0x1840
>
>
[...]
>>
>>>
>>>
>>>
>>
>> Heiner
>>
>> .
>>
>
> .
>
next prev parent reply other threads:[~2019-07-30 19:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 9:53 [RFC] net: phy: read link status twice when phy_check_link_status() Yonglong Liu
2019-07-26 18:14 ` Heiner Kallweit
2019-07-29 3:59 ` liuyonglong
2019-07-29 20:57 ` Heiner Kallweit
2019-07-30 4:03 ` liuyonglong
2019-07-30 6:08 ` Heiner Kallweit
2019-07-30 6:35 ` liuyonglong
2019-07-30 6:39 ` liuyonglong
2019-07-30 19:04 ` Heiner Kallweit [this message]
2019-07-31 3:33 ` liuyonglong
2019-07-31 5:44 ` Heiner Kallweit
2019-07-31 5:58 ` liuyonglong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9a0a8094-42ee-0a18-0e9a-d3ca783d6d4b@gmail.com \
--to=hkallweit1@gmail.com \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxarm@huawei.com \
--cc=liuyonglong@huawei.com \
--cc=netdev@vger.kernel.org \
--cc=salil.mehta@huawei.com \
--cc=shiju.jose@huawei.com \
--cc=yisen.zhuang@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox