From: Tony Lindgren Subject: Re: Regression in v4.20 with net phy soft reset changes Date: Thu, 10 Jan 2019 08:09:17 -0800 Message-ID: <20190110160917.GY5544@atomide.com> References: <20190109190650.GT5544@atomide.com> <20190109213611.GU5544@atomide.com> <79c57d19-837e-4468-f6b4-b3bfa9dde82a@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <79c57d19-837e-4468-f6b4-b3bfa9dde82a@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Sekhar Nori Cc: Heiner Kallweit , Florian Fainelli , "David S. Miller" , Andrew Lunn , Bartosz Golaszewski , Chris Healy , Clemens Gruber , Ivan Khoronzhuk , Keerthy , Murali Karicheri , Rex Chang , Tero Kristo , WingMan Kwok , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org List-Id: linux-omap@vger.kernel.org * Sekhar Nori [190110 11:52]: > On 10/01/19 3:06 AM, Tony Lindgren wrote: > > For TI hardware, Sekhar and TI network folks, can you guys > > please check the various TI SoCs for multiple suspend resume > > cycles with v5.0-rc1 and patch accordingly? See also below > > Will do. OK thanks! > I don't see the link problem if I shift to 100Mps prior to the > plug/unplug experiment using ethtool. So looks like the problem is > restricted to Gigabit link only. Are you using Gigabit link too? Yes this is a Gigabit link. > I think we should patch drivers/net/phy/micrel.c to solve the > regression. Not sure of the root cause though. In the errata pointed to > by Heiner, there is "Module 6" which comes close to what we are seeing, > except it talks of a scenario where auto-negotiation is turned off 100M > link is used and we see the issue even with auto-neg on and in gigabit > mode. "Module 5" is also related to link failure, but is already worked > around in kernel with ksz9031_center_flp_timing(). > > >>> Keerthy noticed this may not happen on the first resume, but usually > >>> happens after few suspend resume cycles. The most working suspend resume > >>> cycles I've seen with the commit above is three. > > ... > >>> Note that unrelated to the commit above, there may be other issues too > >>> as the cpsw phy LED seems to come on only after about five seconds with > >>> about total of 10 seconds before the Ethernet is up again. > > I don't quite see this problem on the AM437x GP EVM. I have seen gigabit > link takes quite some time (sometimes more than 10 seconds) on x15 EVM. > Not sure if the problem you are facing is related to gigabit too. If you > are using gigabit link, can you downgrade to 100MBps to check? Either > using a 100M only switch or by using ethtool on the EVM. > > $ ethtool -s eth0 speed 100 duplex full Yes this makes the 10 second resume latency go away on am437x-sk-evm here. Regards, Tony