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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53903EB64DD for ; Thu, 13 Jul 2023 11:08:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233140AbjGMLIt (ORCPT ); Thu, 13 Jul 2023 07:08:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234337AbjGMLIr (ORCPT ); Thu, 13 Jul 2023 07:08:47 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0AA4A211E for ; Thu, 13 Jul 2023 04:08:47 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id 41be03b00d2f7-55779047021so360183a12.3 for ; Thu, 13 Jul 2023 04:08:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1689246526; x=1691838526; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=f0SCl9wtNC1xsNq6o1Hy/kDLjNTTfMjAPYAoq37IZiQ=; b=SxDGEL5mR4ZVkowiwd39mbb6VyFO9zWtVAfelpzjWrPK7NQEbCigxE5p0mlUBOX66P aX3IcKPfuPVomzim+TkTmBIAWvRqkB8ZfwPZMVjQazZZabf7ZRX//CbP4ZdI24O41dic 8sSPAnqeHzuyAh3z9sX9UyKDCEuAKk0vCHlDEwV0JZUoB6OnbTcE6RLBgEiLZ66iJl02 NZBxLtFcrJ6fvcGD+m/nf97NElF/G+Jp2ZRsHhMK4Q1qv4UB0olVS1AjVCxLihTQOdWQ LYLqfT4I1znHU9dV2SOo3gzt+/xLWn8z0kaeyxVXk/UQ2sy0LTVwsRkmjn2E8oIXlNUE O45A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689246526; x=1691838526; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=f0SCl9wtNC1xsNq6o1Hy/kDLjNTTfMjAPYAoq37IZiQ=; b=J9tHzb/6JHttDFDlfs1HfRYMok38eybFANWN+K7iBlkzfOo+LmBtmvq2ICLkK7EYD2 gHT38olz1KbFpoZ66cgy/F+7Xa+CN/otB1yRwbJILhD8/uO0ouLfa5j2uyYf8d+gSPLo dk2tk4Yx5ozkNus202lJv0B4kGGPzG9RSy6y1zlxFzQSM4PZ5L+vMC496xP3JRI1089U RhnNaYrbMLhXWs/IbMcyrLO7oOFpeIk1C2Vvk/u6JFtJ4JpOXIXmnOascs1tFhGvX6q8 I7JIgZp8+48VYa7UchdLQQetGxGO2xukvRjRA3rB5/jDSwjxM25T7BwISOWpdvDaxYAt XCEw== X-Gm-Message-State: ABy/qLZ/bikNBzXCa1fpItuQv1/jfrIgjyvC6y2u1F1dZBFAAwSDqYY8 3FYhrvZbdb+FGwx9FmEzc0rcqTlAsu8= X-Google-Smtp-Source: APBJJlEgJOS4O2XkhmVwsTkW+GQBka9H2tmVUVj6SzdwBKyOpynaabQ0Ej9ww28ZAce5y8YL33D2OA== X-Received: by 2002:a17:902:db10:b0:1b8:5bf5:543a with SMTP id m16-20020a170902db1000b001b85bf5543amr693440plx.49.1689246526342; Thu, 13 Jul 2023 04:08:46 -0700 (PDT) Received: from sol (194-223-178-180.tpgi.com.au. [194.223.178.180]) by smtp.gmail.com with ESMTPSA id jw16-20020a170903279000b001b8b45b177esm5632974plb.274.2023.07.13.04.08.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jul 2023 04:08:45 -0700 (PDT) Date: Thu, 13 Jul 2023 19:08:41 +0800 From: Kent Gibson To: "Hollerer Franz, Schrack Seconet AG, Entwicklung" Cc: "linux-gpio@vger.kernel.org" , "Ullrich Lucas, Schrack Seconet AG, Entwicklung" , Bartosz Golaszewski Subject: Re: [libgpiod]: non-exclusive use of input lines Message-ID: References: <1337f994e3ad45f49dc86787bcb3a019@schrack-seconet.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1337f994e3ad45f49dc86787bcb3a019@schrack-seconet.com> Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Thu, Jul 13, 2023 at 09:24:03AM +0000, Hollerer Franz, Schrack Seconet AG, Entwicklung wrote: > > I have several processes (one of them is a shell scripts, others are > C/C++ programs) which need to read the same input line. > Is it somehow possible to request input lines for non-exclusive use? No, it is not possible. > If not, is this a feature which will be added sometime in the future? > No, there are no plans for such a feature, AFAIAA. The solution is to have a userspace process monitor the line and share the value with the other processes. How best to do that is up to you. A simple approach would be to write the value to a file. (which might be a useful mode to add to gpiomon??) Bart is working on a daemon that may provided shared read access, but I'm just guessing. Cheers, Kent.