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_PASS,URIBL_BLOCKED autolearn=unavailable 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 96EC3C282DC for ; Wed, 17 Apr 2019 14:37:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 681F7206BA for ; Wed, 17 Apr 2019 14:37:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="e3xfUkCx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732528AbfDQOhX (ORCPT ); Wed, 17 Apr 2019 10:37:23 -0400 Received: from mail-oi1-f193.google.com ([209.85.167.193]:33349 "EHLO mail-oi1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732259AbfDQOhX (ORCPT ); Wed, 17 Apr 2019 10:37:23 -0400 Received: by mail-oi1-f193.google.com with SMTP id e5so20226783oii.0; Wed, 17 Apr 2019 07:37:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=KVL9KF/YoHtzs8IjWHwRGHOY6DKDTBP7zc6ndr7tx5s=; b=e3xfUkCx499Q6ZWEuv72GXYEVXGDx+7aGV3XVxUyeFEoIihqBm6FuWKDh9k85LraPC FPDWDfh9VNEGQ1Oacjd+VFEKMG8t+2DaIVBhzLyJryqpeCMYgb9PvNW8ilS2WeHdQlYY s1yx5EL43kQ5aVZQLckp9ZuEa1uIsQbChvnG3DJVwMwlyktsnKQmnMHWvla97c5JNBbB coXPfWAZz16bq8iPuYkakDREYFwPomhRHWG+zu4ouHbIfJzyy9g5TkdWxYiVLhe4idji /178jEtlfgcqsW1Brt/zS7UKc399eFbJ0y0xbfFS09iZopZEfGliGDUThMCKftIaCmvh V1lA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KVL9KF/YoHtzs8IjWHwRGHOY6DKDTBP7zc6ndr7tx5s=; b=JfT3nIUUL06TuMV+6sJJOMaOsHgGoEMU7EWZ/k3idwn6ehfVdJ1uAYNQEpjPzf1jBa EFMlCTld/SlWXeAOhm+oOBcuAuzwhkAipwgvEjPL2XOEuu8GcBOeNWhvtDfES9E0zXwn HeRHR+TJePTpuiRaK0U0inr81mWoE0CgH/s3qh0YxJC6X/x+N/WwXkZRVn5xFkDIZenO bzNhC9nW6zD6BPfiDvY430pJ+al4IvBD1UNFki0c+MDZ1cUpZUkND+zlMtouL9/CM+Jc wZpHNcISX1FjClNnINYeUy8MWWwKNLKEUPz+o5y9YPW/x+/Akm1rDkSkvG5HOVlSCvmh yKiA== X-Gm-Message-State: APjAAAVtiNGFJQ99ToHD+f5Q6QRvaLVD6jHBvgMrOY6K/Sm7RsUUZQBJ dq8k6cdvL4YYzCVKCtdesI9A6gvdWXsWMl5QSyM= X-Google-Smtp-Source: APXvYqwzzDkTed9Kh/UGRtG/0sH/YvObQ9TaaQaBnqTEbeqLHTGrdH2kSDOwSiAltGeQPXi68t/6LeQi8m9SrMWNciE= X-Received: by 2002:aca:4202:: with SMTP id p2mr25429168oia.169.1555511842207; Wed, 17 Apr 2019 07:37:22 -0700 (PDT) MIME-Version: 1.0 References: <20190409144250.7237-1-TheSven73@gmail.com> <982e69c6-4e68-6f62-8bed-cd5a1802272b@metux.net> <23a25601-ed98-5348-9bac-bf8fc2baea5e@metux.net> In-Reply-To: <23a25601-ed98-5348-9bac-bf8fc2baea5e@metux.net> From: Sven Van Asbroeck Date: Wed, 17 Apr 2019 10:37:11 -0400 Message-ID: Subject: Re: [PATCH v10 0/7] Add Fieldbus subsystem + support HMS Profinet card To: "Enrico Weigelt, metux IT consult" Cc: Rob Herring , Linus Walleij , Lee Jones , mark.rutland@arm.com, =?UTF-8?Q?Andreas_F=C3=A4rber?= , treding@nvidia.com, David Lechner , noralf@tronnes.org, johan@kernel.org, Michal Simek , michal.vokac@ysoft.com, Arnd Bergmann , Greg KH , john.garry@huawei.com, geert+renesas@glider.be, robin.murphy@arm.com, Paul Gortmaker , sebastien.bourdelin@savoirfairelinux.com, icenowy@aosc.io, Stuart Yoder , "J. Kiszka" , maxime.ripard@bootlin.com, Linux Kernel Mailing List , netdev Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Apr 16, 2019 at 5:21 PM Enrico Weigelt, metux IT consult wrote: > > Yet another question: does each fieldbus_dev instance talk to exactly > one plc process memory, or can there be many ? I'm by no means a fieldbus expert, so I had a little chat with one of the fieldbus people in the company here. AFAIK if multiple plcs connect to the same device, all of them 'see' the same process memory for that device. Any mechanism to prevent these plcs from racing with each other is implemented in the application software. Could be handshaking, could be each plc dealing with a separate section of the process memory. So for a fieldbus *device* (which is what this subsystem deals with) there can only be a single process memory. So we have a single devnode per device. A fieldbus *controller* would have one process memory per device it connects to. But this subsystem does not deal with controllers. This is my understanding, but I'd appreciate your input if I have overlooked something.