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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 5004DC433E1 for ; Tue, 7 Jul 2020 14:29:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2EBB820771 for ; Tue, 7 Jul 2020 14:29:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Eig7ACSN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728149AbgGGO3c (ORCPT ); Tue, 7 Jul 2020 10:29:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbgGGO3b (ORCPT ); Tue, 7 Jul 2020 10:29:31 -0400 Received: from mail-lj1-x233.google.com (mail-lj1-x233.google.com [IPv6:2a00:1450:4864:20::233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78D27C061755; Tue, 7 Jul 2020 07:29:31 -0700 (PDT) Received: by mail-lj1-x233.google.com with SMTP id h22so42980634lji.9; Tue, 07 Jul 2020 07:29:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version; bh=Or0lYQVNJ3ZFTvEKcGdp6AoYMkJnpUEvesCucB/s/eA=; b=Eig7ACSNKBihkxVTkdaoPlJSPR9yhc5A1NgIfryFh+aZ1/OPt2JF7JxQ9qMEyRo0WC JBnmuriXLXe07JxKRZmEq3I+j3Fnh9y6bdCe0b9aRUqpfUByxrQe+oAkuXqj7W4BEg1q 2GIYlJpL/9/DCgnQizPEUSwVzx/a75C27STAid79ScuTBY8VN+wd1Ro6TqLWcnFaOe1e TaKd1Ne5LmiEzjkN9EsoMcTpEmouff7AWvIj7wF/TVwlb3n9Hhs6/QCfmLS+zzWB2v+Z R+BTbLWr99QWhCTg0PEMIxUSV3x49yVfAVxyg3DylSjTM3ihrpIFX+svZ8SPwYbbzTcM lWHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:references:date:in-reply-to :message-id:user-agent:mime-version; bh=Or0lYQVNJ3ZFTvEKcGdp6AoYMkJnpUEvesCucB/s/eA=; b=Msf2mls/8xtgr0wdqajnuR0GdNcKhXArtN36q3EKw7WjDFPzaQyHf3ci0SWWBEl9q4 ttU2EvFVWTajUUIdSwBHE9AMwqYGah/6fcOWGecmk69pOEwjF2Ug2Me8Py4Nh7OMM19C q+pxN7LqZfLUx4CWAYM/4wUNOA5WUhf59CajlXYTT9W9wbxDD8xJq5byxxQ7pTtRwAj+ tc+iwGG6+3BrH37SS5fObwGgVcs4+s3a+h0+mJD1GYidsLVKBrbdMNNVdoMhBV1Pv6m9 y4K3GwqDjcRapD0fk3dH94vmD8o52tb3Ng9vj+Rn0RZKU/rcThwTIvRcOodZk39yyiWh Fxdg== X-Gm-Message-State: AOAM5307CdfLsqtOBh7tGKYhTabe6OdqN3Hf3t/C1rcfkkbHiABzFuf6 1SSXlSosf0Jq194YgF3fXz8= X-Google-Smtp-Source: ABdhPJz4sWveRvaDilxkO9hwX6+QdFoRWNRQHSqXz94U8JBhMiIIFwRF5pq38V9KwcotVknmy0Yr8g== X-Received: by 2002:a2e:8799:: with SMTP id n25mr24136611lji.416.1594132169997; Tue, 07 Jul 2020 07:29:29 -0700 (PDT) Received: from osv.localdomain ([89.175.180.246]) by smtp.gmail.com with ESMTPSA id m15sm227262ljp.45.2020.07.07.07.29.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Jul 2020 07:29:29 -0700 (PDT) From: Sergey Organov To: Andy Duan Cc: "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "David S. Miller" , Jakub Kicinski Subject: Re: [EXT] [PATCH 2/5] net: fec: enable to use PPS feature without time stamping References: <20200706142616.25192-1-sorganov@gmail.com> <20200706142616.25192-3-sorganov@gmail.com> Date: Tue, 07 Jul 2020 17:29:28 +0300 In-Reply-To: (Andy Duan's message of "Tue, 7 Jul 2020 04:05:11 +0000") Message-ID: <871rln9z5j.fsf@osv.gnss.ru> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Duan writes: > From: Sergey Organov Sent: Monday, July 6, 2020 10:26 PM >> PPS feature could be useful even when hardware time stamping of network >> packets is not in use, so remove offending check for this condition from >> fec_ptp_enable_pps(). > > If hardware time stamping of network packets is not in use, PPS is > based on local > clock, what is the use case ? First, having special code to disable something that does no harm seems to be wrong idea in general. In this particular case, if PPS is not needed, it is still disabled by default, and one is still free not to use it. Then, as I'm not aware of a rule that renders PPS based on local clock useless, I'm to assume it might be useful. Finally, as an attempt to give direct answer to your question, suppose I have external device that is capable to time stamp PPS against known time scale (such as GPS system time) with high precision. Now I can get nice estimations of local time drifts and feed, say, "chrony", with the data to adjust my local clock accordingly. Thanks, -- Sergey