Messages in this thread | | | Subject | net: phy: SMSC LAN8710/LAN8720 high load | From | Teresa Remmet <> | Date | Mon, 11 Jan 2016 08:41:55 +0100 |
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Hello,
we have noticed load issues on our AM335x boards with a LAN8710 phy while cpu is idling using 4.4-rc8.
CPU: 0% usr 0% sys 0% nic 99% idle 0% io 0% irq 0% sirq Load average: 1.21 1.16 1.00 1/84 372
We could track this down to the ethernet phy. And bisect the issue to the following patch:
commit 776829de90c5972895db398993ddfa9417ff8b01 Author: Igor Plyatov <plyatov@gmail.com> Date: Fri Aug 14 20:11:02 2015 +0300
net: phy: workaround for buggy cable detection by LAN8700 after cable plugging * Due to HW bug, LAN8700 sometimes does not detect presence of energy in the Ethernet cable in Energy Detect Power-Down mode (e.g while EDPWRDOWN bit is set, the ENERGYON bit does not asserted sometimes). This is a common bug of LAN87xx family of PHY chips. * The lan87xx_read_status() was improved to acquire ENERGYON bit. Its previous algorythm still not reliable on 100 % and sometimes skip cable plugging.
Signed-off-by: Igor Plyatov <plyatov@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Reverting the commit helped to make the load drop down to:
09:21:01 up 32 min, load average: 0.19, 0.17, 0.14
In both cases no ethernet cable as been connected.
We also struggle with the buggy cable detection issue, but this increase of load doesn't seem acceptable.
Can someone else with a LAN87xx also reproduce this?
Regards Teresa
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