From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Gmeiner Subject: Re: Freescale FEC packet loss Date: Thu, 6 Feb 2014 10:42:00 +0100 Message-ID: References: <201401222255.29467.marex@denx.de> <201401262012.13051.marex@denx.de> <1390772013.2735.47.camel@deadeye.wl.decadent.org.uk> <201401280201.39174.marex@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Ben Hutchings , "fabio.estevam@freescale.com" , Matthew Garrett , Frank Li , Detlev Zundel , "netdev@vger.kernel.org" , Eric Nelson , Hector Palacios , fugang.duan@freescale.com, "linux-arm-kernel@lists.infradead.org" To: Marek Vasut Return-path: Received: from mail-we0-f170.google.com ([74.125.82.170]:50311 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755503AbaBFJmV (ORCPT ); Thu, 6 Feb 2014 04:42:21 -0500 Received: by mail-we0-f170.google.com with SMTP id w62so1117341wes.1 for ; Thu, 06 Feb 2014 01:42:20 -0800 (PST) In-Reply-To: <201401280201.39174.marex@denx.de> Sender: netdev-owner@vger.kernel.org List-ID: 2014-01-28 Marek Vasut : > On Sunday, January 26, 2014 at 10:33:33 PM, Ben Hutchings wrote: >> On Sun, 2014-01-26 at 20:12 +0100, Marek Vasut wrote: >> > On Sunday, January 26, 2014 at 07:56:30 PM, Ben Hutchings wrote: >> > > On Wed, 2014-01-22 at 22:55 +0100, Marek Vasut wrote: >> > > > Hi guys, >> > > > >> > > > I am running stock Linux 3.13 on i.MX6Q SabreLite board. The CPU is >> > > > i.MX6Q TO 1.0 . >> > > > >> > > > I am hitting a WARNING when I use the FEC ethernet to transfer data, >> > > > thus I started investigating this problem. TL;DR I am not able to >> > > > figure this problem out, so I am not attaching a patch :-( >> > > > >> > > > Steps to reproduce: >> > > > ------------------- >> > > > 1) Boot stock Linux 3.13 on i.MX6Q SabreLite board >> > > > 2) Plug in an SD card into one of the SD slots (I use the full-size >> > > > one) 3) Plug in an USB stick into one of the USB ports (I use the >> > > > upper one) 4) Plug in an ethernet cable into the board >> > > > >> > > > -> Connect the other side into a gigabit-capable PC >> > > >> > > [...] >> > > >> > > I think there are known problems with 1000BASE-T on the Sabre Lite >> > > board. >> > >> > This is MX6-wide thing, not sabrelite specific actually. >> > >> > > Two possible workarounds are to limit the PHY to 100BASE-TX >> > > (should be doable with ethtool) or force it to be clock master for >> > > 1000BASE-T (requires a driver patch). >> > >> > Can you please elaborate on the later ? I don't quite understand that. >> >> 1000BASE-T uses all 4 pairs in both directions at the same time, which >> requires that both ends transmit symbols synchronously. As part of the >> autonegotiation protocol, they decide which is the clock master (using a >> local clock generator) and which is the clock slave (generating a clock >> from the received signal). A PHY can be configured to support only one >> of these roles. > > I checked the patch you pointed me to. The patch basically messes with the > CTL1000 (0x9) register of the PHY, right ? I did the adjustments to the PHY > register manually , but the result is still the same (backtrace). > > I did two different kinds of adjustment: > 1) reg 0x9 |= 0x1800; > 2) reg 0x9 |= 0x1000; > In both cases, the crash did happen. I verified the PHY register was configured > as necessary. The KSZ9021 PHY bit 12 configures the master/slave override, same > as the patch does. The bit 11 forces either master or slave mode for the PHY. In > both cases the crash was there. > > I think this patch won't help in this case, sorry. > Are there still problems with 3.13.1 kernel regarding FEC networking? Does this only affect the SabreLite? greets -- Christian Gmeiner, MSc https://soundcloud.com/christian-gmeiner