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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 F2160C54E8E for ; Mon, 11 May 2020 14:59:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBFDE206F9 for ; Mon, 11 May 2020 14:59:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729881AbgEKO7a (ORCPT ); Mon, 11 May 2020 10:59:30 -0400 Received: from mx2.suse.de ([195.135.220.15]:34164 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729766AbgEKO7a (ORCPT ); Mon, 11 May 2020 10:59:30 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id CBD3DADC2; Mon, 11 May 2020 14:59:30 +0000 (UTC) Received: by lion.mk-sys.cz (Postfix, from userid 1000) id 6182A6033E; Mon, 11 May 2020 16:59:26 +0200 (CEST) Date: Mon, 11 May 2020 16:59:26 +0200 From: Michal Kubecek To: Oleksij Rempel Cc: Andrew Lunn , "David S. Miller" , Florian Fainelli , Heiner Kallweit , Jakub Kicinski , Jonathan Corbet , David Jander , kernel@pengutronix.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Russell King , mkl@pengutronix.de, Marek Vasut , Christian Herber Subject: Re: signal quality and cable diagnostic Message-ID: <20200511145926.GC8503@lion.mk-sys.cz> References: <20200511141310.GA2543@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200511141310.GA2543@pengutronix.de> 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 Mon, May 11, 2020 at 04:13:10PM +0200, Oleksij Rempel wrote: > > I continue to work on TJA11xx PHY and need to export some additional > cable diagnostic/link stability information: Signal Quality Index (SQI). > The PHY data sheet describes it as following [1]: > ================================================================================ > 6.10.3 Link stability > > The signal-to-noise ratio is the parameter used to estimate link > stability. The PMA Receive function monitors the signal-to-noise ratio > continuously. Once the signal-to-noise ratio falls below a configurable > threshold (SQI_FAILLIMIT), the link status is set to FAIL and > communication is interrupted. The TJA1100 allows for adjusting the > sensitivity of the PMA Receive function by configuring this threshold. > The microcontroller can always check the current value of the > signal-to-noise ratio via the SMI, allowing it to track a possible > degradation in link stability. > ================================================================================ > > Since this functionality is present at least on TJA11xx PHYs and > mandatory according to Open Alliance[2], I hope this functionality is > present on other 100/1000Base-T1 PHYs. So may be some common abstraction > is possible. What would be the best place to provide it for the user > space? According to the [2] SQI, is the part of Dynamic Channel Quality > (DCQ) together with Mean Square Error (MSE) and Peak MSE value (pMSE). IIUC these would be read-only parameters describing current state of the link which can be queried at any time. If this is the case, adding them as attributes to ETHTOOL_MSG_LINKSTATE_GET_REPLY message seems most fitting. As for getting / setting the threshold, perhaps ETHTOOL_MSG_LINKINFO_GET and ETHTOOL_MSG_LINKINFO_SET. Unless you expect more configurable parameters like this in which case we may want to consider adding new request type (e.g. link params or link management). Michal