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=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 B7F6FC4743E for ; Fri, 4 Jun 2021 17:32:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BE846140C for ; Fri, 4 Jun 2021 17:32:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231320AbhFDRee (ORCPT ); Fri, 4 Jun 2021 13:34:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:57886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230185AbhFDRee (ORCPT ); Fri, 4 Jun 2021 13:34:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 743ED61400; Fri, 4 Jun 2021 17:32:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622827967; bh=a5isDehEudac8CyR2HZE1gI9Wve6E9W6CiVt055MqQI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oxwiF4nZxQ/b7p8BNP/PiIQXi+nFKiMXwGXug/6MEsZ6c41FePwwtM7mqcB7KViyq rFTdSJGYKWUDkg4CL+tWbpAb8pYvbDdnBJ4mckYht5plojekusly9vfUpWIgdBJ7KC FRb01Oi09iHmr1pe4hVKD4Ye3DNlKFLYDWxPbU66N/skaboEQkSHf+xUEpqNA313Xc Il6Ywgnr/Ftta+jZ+n+FwxYPtLjDlJ+ENr0Te4dSIU5tSgxpmeJ9+fSBw9Fvw8CvwP kCHZ1HGCchNOvnukeKkSeZGc/Wla+hQnzNolCjGWuXAO5egR08CKUMCUzm+wRXvQU1 ohJmjn0VGkZKw== Received: by pali.im (Postfix) id 1ED85990; Fri, 4 Jun 2021 19:32:45 +0200 (CEST) Date: Fri, 4 Jun 2021 19:32:44 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Madalin Bucur Cc: Andrew Lunn , Igal Liberman , Shruti Kanetkar , Emil Medve , Scott Wood , Rob Herring , Michael Ellerman , Benjamin Herrenschmidt , Russell King , "netdev@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Camelia Alexandra Groza (OSS)" Subject: Re: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts Message-ID: <20210604173244.qonw5wsn3pq6gyjf@pali> References: <20210603143453.if7hgifupx5k433b@pali> <20210603194853.ngz4jdso3kfncnj4@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! On Friday 04 June 2021 07:35:33 Madalin Bucur wrote: > > -----Original Message----- > > From: Pali Rohár > > Sent: 03 June 2021 22:49 > > To: Andrew Lunn > > Cc: Igal Liberman ; Shruti Kanetkar > > ; Emil Medve ; Scott > > Wood ; Rob Herring ; Michael > > Ellerman ; Benjamin Herrenschmidt > > ; Madalin Bucur ; Russell > > King ; netdev@vger.kernel.org; > > devicetree@vger.kernel.org; linux-kernel@vger.kernel.org > > Subject: Re: Unsupported phy-connection-type sgmii-2500 in > > arch/powerpc/boot/dts/fsl/t1023rdb.dts > > > > On Thursday 03 June 2021 17:12:31 Andrew Lunn wrote: > > > On Thu, Jun 03, 2021 at 04:34:53PM +0200, Pali Rohár wrote: > > > > Hello! > > > > > > > > In commit 84e0f1c13806 ("powerpc/mpc85xx: Add MDIO bus muxing support > > to > > > > the board device tree(s)") was added following DT property into DT > > node: > > > > arch/powerpc/boot/dts/fsl/t1023rdb.dts fm1mac3: ethernet@e4000 > > > > > > > > phy-connection-type = "sgmii-2500"; > > > > > > > > But currently kernel does not recognize this "sgmii-2500" phy mode. > > See > > > > file include/linux/phy.h. In my opinion it should be "2500base-x" as > > > > this is mode which operates at 2.5 Gbps. > > > > > > > > I do not think that sgmii-2500 mode exist at all (correct me if I'm > > > > wrong). > > > > > > Kind of exist, unofficially. Some vendors run SGMII over clocked at > > > 2500. But there is no standard for it, and it is unclear how inband > > > signalling should work. Whenever i see code saying 2.5G SGMII, i > > > always ask, are you sure, is it really 2500BaseX? Mostly it gets > > > changed to 2500BaseX after review. > > > > So this is question for authors of that commit 84e0f1c13806. But it > > looks like I cannot send them emails because of following error: > > > > : connect to freescale.com[192.88.156.33]:25: > > Connection timed out > > > > Do you have other way how to contact maintainers of that DTS file? > > arch/powerpc/boot/dts/fsl/t1023rdb.dts > > > > > PHY mode sgmii-2500 does not exist in mainline. > > > > Yes, this is reason why I sent this email. In DTS is specified this mode > > which does not exist. > > > > > Andrew > > Hi, the Freescale emails no longer work, years after Freescale joined NXP. > Also, the first four recipients no longer work for NXP. > > In regards to the sgmii-2500 you see in the device tree, it describes SGMII > overclocked to 2.5Gbps, with autonegotiation disabled. > > A quote from a long time ago, from someone from the HW team on this: > > The industry consensus is that 2.5G SGMII is overclocked 1G SGMII > using XAUI electricals. For the PCS and MAC layers, it looks exactly > like 1G SGMII, just with a faster clock. SGMII supports 1 Gbps speed and also 100 / 10 Mbps by repeating frame 10 or 100 times. So... if this HW has 2.5G SGMII (sgmii-2500) as 2.5x overclocked SGMII, does it mean that 2.5G SGMII supports 25 Mbps and 250 Mbps speeds by repeating frame 10 and 100 times (like for 1G SGMII)? > The statement that it does not exist is not accurate, it exists in HW, and > it is described as such in the device tree. Whether or not it is properly > treated in SW it's another discussion. In 2015, when this was submitted, > there were no other 2.5G compatibles in use, if I'm not mistaken. Yea, I understand. If at that time there was no sw support, "something" was chosen. > 2500Base-X started to be added to device trees four years later, it should > be compatible/interworking but it is less specific on the actual implementation > details (denotes 2.5G speed, 8b/10b coding, which is true for this overclocked > SGMII). If they are compatible, SW should probably treat them in the same manner. 1000base-x and SGMII are not same modes. E.g. SGMII support 10 Mbps while 1000base-x not. So in my opinion 1000base-x and SGMII should not be treated as the same mode (in SW). I'm not sure how what exactly SGMII-2500 supports, but as 2500base-x does not support 25 Mbps speed I do not think that SGMII-2500 is same as 2500base-x. But now I'm totally confused by all these modes, so I hope that somebody else tries to explain what kernel expects and how kernel treats these modes. > There were some discussions a while ago about the mix or even confusion between > the actual HW description (that's what the dts is supposed to do) and the settings > one wants to represent in SW (i.e. speed) denoted loosely by denominations like > 10G Base-R. > > Regards, > Madalin