From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758686AbcAKHsI (ORCPT ); Mon, 11 Jan 2016 02:48:08 -0500 Received: from mail.phycard.co.uk ([217.6.246.34]:39096 "EHLO root.phytec.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752602AbcAKHsG (ORCPT ); Mon, 11 Jan 2016 02:48:06 -0500 X-Greylist: delayed 307 seconds by postgrey-1.27 at vger.kernel.org; Mon, 11 Jan 2016 02:48:05 EST Message-ID: <1452498115.7467.23.camel@lws-tremmet.phytec.de> Subject: net: phy: SMSC LAN8710/LAN8720 high load From: Teresa Remmet To: Igor Plyatov , "David S. Miller" Cc: Florian Fainelli , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 11 Jan 2016 08:41:55 +0100 X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 X-MIMETrack: Itemize by SMTP Server on Idefix/Phytec(Release 9.0.1FP4|June 07, 2015) at 11.01.2016 08:42:54, Serialize by Router on Idefix/Phytec(Release 9.0.1FP4|June 07, 2015) at 11.01.2016 08:42:54, Serialize complete at 11.01.2016 08:42:54 X-TNEFEvaluated: 1 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 Signed-off-by: David S. Miller 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