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=-2.3 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 AF888C433E1 for ; Sun, 24 May 2020 21:28:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9855C207FB for ; Sun, 24 May 2020 21:28:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388186AbgEXV2A (ORCPT ); Sun, 24 May 2020 17:28:00 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:57578 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387830AbgEXV17 (ORCPT ); Sun, 24 May 2020 17:27:59 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 3E8EB1C02AB; Sun, 24 May 2020 23:27:58 +0200 (CEST) Date: Sun, 24 May 2020 23:27:57 +0200 From: Pavel Machek To: Christian Herber Cc: Oleksij Rempel , Andrew Lunn , "David S. Miller" , Florian Fainelli , Heiner Kallweit , Jakub Kicinski , Jonathan Corbet , Michal Kubecek , David Jander , "kernel@pengutronix.de" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , Russell King , "mkl@pengutronix.de" , Marek Vasut Subject: Re: signal quality and cable diagnostic Message-ID: <20200524212757.GC1192@bug> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > > The SNR seems to be most universal value, when it comes to comparing > > different situations (different links and different PHYs). The > > resolution of BER is not that detailed, for the NXP PHY is says only > > "BER below 1e-10" or not. > > The point I was trying to make is that SQI is intentionally called SQI and NOT SNR, because it is not a measure for SNR. The standard only suggest a mapping of SNR to SQI, but vendors do not need to comply to that or report that. The only mandatory requirement is linking to BER. BER is also what would be required by a user, as this is the metric that determines what happens to your traffic, not the SNR. > > So when it comes to KAPI parameters, I see the following options > - SQI only > - SQI + plus indication of SQI level at which BER<10^-10 (this is the only required and standardized information) > - SQI + BER range (best for users, but requires input from the silicon vendors) Last option looks best to me... and it will mean that hopefully silicon vendors standartize something in future. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html