From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8930C33CB3 for ; Sat, 1 Feb 2020 11:49:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF1BB20661 for ; Sat, 1 Feb 2020 11:49:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="mFGne9DF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726495AbgBALtw (ORCPT ); Sat, 1 Feb 2020 06:49:52 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:58814 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726336AbgBALtv (ORCPT ); Sat, 1 Feb 2020 06:49:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=HnpDr+EYlr+rwm3PugQQ1cWKXYWrIicGoMrGWJGDElk=; b=mFGne9DFt/gmDPWvq8GGbODr4 74nkRl91SC6LnethSOBtJMY5ldDSVaTOJgrNiP5qkc9yB86oVQX/tbny09bLUK4rStaKyy5P8RsR0 EXxE4na+G0wFzokc5ThlRXoqlXf768UOkfTqmDCGudbfGl607aU6Gy/JCiF9QqUxdZqjtWko90z+6 5VzyMmfNrU3DSggP+As0u+Mzhv3lGLHNQ1325AvgVAIGrP1Z8SrX1BannNYfA+WxcMU/rV4HKOt+/ FvfzQAUlYc66AKckYu/TqHvMCyaq+WrZnKowM6J9PFG+KBuSWcpRngFGnClh3i8bKnwAOdr/WBs0V EePQFJ2uw==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:34528) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ixrHC-000704-FV; Sat, 01 Feb 2020 11:49:26 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1ixrH5-0006Mc-Oa; Sat, 01 Feb 2020 11:49:19 +0000 Date: Sat, 1 Feb 2020 11:49:19 +0000 From: Russell King - ARM Linux admin To: Jakub Kicinski , Jiri Pirko Cc: Andrew Lunn , Robin Murphy , Calvin Johnson , stuyoder@gmail.com, nleeder@codeaurora.org, Ioana Ciornei , Cristi Sovaiala , Hanjun Guo , Will Deacon , Lorenzo Pieralisi , Marc Zyngier , Pankaj Bansal , Jon Nettleton , ACPI Devel Maling List , Len Brown , Jason Cooper , Andy Wang , Makarand Pawagi , Varun Sethi , Thomas Gleixner , linux-arm-kernel , Laurentiu Tudor , Paul Yang , Ard Biesheuvel , "" , "Rafael J. Wysocki" , Linux Kernel Mailing List , Shameerali Kolothum Thodi , Sudeep Holla Subject: Re: [EXT] Re: [PATCH] bus: fsl-mc: Add ACPI support for fsl-mc Message-ID: <20200201114919.GQ25745@shell.armlinux.org.uk> References: <12531d6c569c7e14dffe8e288d9f4a0b@kernel.org> <0680c2ce-cff0-d163-6bd9-1eb39be06eee@arm.com> <20200131142906.GG9639@lunn.ch> <20200131151500.GO25745@shell.armlinux.org.uk> <20200131074050.38d78ff0@cakuba.hsd1.ca.comcast.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200131074050.38d78ff0@cakuba.hsd1.ca.comcast.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jan 31, 2020 at 07:40:50AM -0800, Jakub Kicinski wrote: > On Fri, 31 Jan 2020 15:15:00 +0000, Russell King - ARM Linux admin > wrote: > > I have some prototype implementation for driving the QSFP+ cage, but > > I haven't yet worked out how to sensible deal with the "is it 4x 10G > > or 1x 40G" issue you mention above, and how to interface the QSFP+ > > driver sensibly with one or four network drivers. > > I'm pretty sure you know this but just FWIW - vendors who do it in FW > write the current config down in NVM so it doesn't get affected by > reboots and use devlink port splitting to change it. +Jiri I wasn't aware of devlink port splitting, so thanks for that. However, it could do with some better documentation - there's nothing on it afaics in the Documentation subdirectory, and "man devlink-port" doesn't give much away either: devlink port split - split devlink port into more DEV/PORT_INDEX - specifies the devlink port to operate on. count COUNT number of ports to split to. It's the "into more" that's not clear - presumably more ports, and presumably each port is a network device, but this isn't explained. I think what this is trying to say is that, if we have a QSFP+ cage with 4 serdes lines running at 10G, and they are initially treated as a single 40G ethernet: devlink port split device/1 count 4 will then give us four 10G network devices, and: devlink port unsplit device/1 will recombine them back to a single 40G network device. What if someone decides to do: devlink port split device/1 count 2 what do we end up with? Presumably two network devices running with two serdes lanes each (if supported by the hardware). At that point can they then do: devlink port split device/2 count 2 and end up with one network device with two 10G serdes lanes, and two network devices each with one 10G serdes lane, or can port splitting only be used on the "master" device/port ? Unfortunately, I don't think I have any network devices that support this so I can't experiment to find out how this should work; yes, I have a Mellanox card, but it supports a single 10G SFP+, and therefore does not support port splitting. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up