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 C54A7E7849A for ; Mon, 2 Oct 2023 09:25:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236063AbjJBJZR (ORCPT ); Mon, 2 Oct 2023 05:25:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236033AbjJBJZQ (ORCPT ); Mon, 2 Oct 2023 05:25:16 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E455FA4; Mon, 2 Oct 2023 02:25:13 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id 41be03b00d2f7-5859b06509cso2061975a12.2; Mon, 02 Oct 2023 02:25:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696238713; x=1696843513; darn=vger.kernel.org; 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=/qXBB0HN9EE99f58WPeeJJXkwIcpeq4j/UjdEMsKhjw=; b=HW/t03TraU2l+PsoVrnL1idz2UWo9Jk86iLHAgjbKidGXH46NZlD8D2VhMm+mCfavW Bh3+7FJzTR1nsOyeMJ25go/MIcfh8ZOO0Pz0kw8C0GsCYU9ZzqSLuVxRY1zEFxrTolg9 MvwPfljt+Ds17ROUgm1J3WbOrq+ISZqSXRiG/akeLct3ezdykAa51QDg3eWlYVYHRN3D UpZ9UR4GzsCMHf9u2zJIWazpQQeH2lbhaiTm6OMUqkUpf51G6glHSNsEIy7jqB2QFRpZ 9WAAPsrFvvPPoHndr6AhWp44C+AcBrMs8uTBe14zF/7IvPG33Mfz2a9bk+yVqN9NixIm jfUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696238713; x=1696843513; 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=/qXBB0HN9EE99f58WPeeJJXkwIcpeq4j/UjdEMsKhjw=; b=WXMmjFLaVFFA6B3ZyK+852dNuFBlEVu+BlzrldDKmAMa2HOPQ5H7Uln9fBGdkZp2g+ fKUj31AMhxDkngozUyOltbZiR6DDTar+8XhD+5oIuLufmJ+YnC7f+UJMaGTS3Unr+T2J s7oFT1KeQfb/r9rADf8PNj/1x7Tlr+Ddu7pPBYv8ooa1VKtlJq+l3MzfjS/eoKS7MoX9 qlFu8JzGDs8+aqekO98QoIOragMFGlfiF1OKU27pmHxSA7y20o1Ds9vD+S0WqOTqjCli U2DjzDR8RHz+1i3DJHCv43NYmNdGlJBywzlvDUYnzatmoy9s7tfWFBY2S6IazqnaSXH+ wTNg== X-Gm-Message-State: AOJu0YywfkL404E3jr/sqVAXvw8Su8qxlcYCnrUfFBWMW4OEk1ya6CWE ArwZS5WHYdWQ8/IQx0+Wu8s= X-Google-Smtp-Source: AGHT+IHpK5n4dWXV9/SW5f/QoW/AwH52cbiDur8cY38t2xxx74IiU+CRIJ4NkW2HkfVGIR26i63yIQ== X-Received: by 2002:a17:90a:d513:b0:274:9200:3973 with SMTP id t19-20020a17090ad51300b0027492003973mr8047443pju.36.1696238713240; Mon, 02 Oct 2023 02:25:13 -0700 (PDT) Received: from sol ([118.209.204.34]) by smtp.gmail.com with ESMTPSA id 25-20020a17090a031900b00279060a0fccsm6387016pje.9.2023.10.02.02.25.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 02:25:12 -0700 (PDT) Date: Mon, 2 Oct 2023 17:25:05 +0800 From: Kent Gibson To: Andy Shevchenko Cc: Linus Walleij , Bartosz Golaszewski , Yury Norov , linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Shubhrajyoti Datta , Srinivas Neeli , Michal Simek , Bartosz Golaszewski , Rasmus Villemoes , Marek =?iso-8859-1?Q?Beh=FAn?= Subject: Re: [PATCH v1 5/5] gpiolib: cdev: Utilize more bitmap APIs Message-ID: References: <20230926052007.3917389-1-andriy.shevchenko@linux.intel.com> <20230926052007.3917389-6-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Mon, Oct 02, 2023 at 12:05:11PM +0300, Andy Shevchenko wrote: > On Wed, Sep 27, 2023 at 10:23:12PM +0800, Kent Gibson wrote: > > On Wed, Sep 27, 2023 at 04:59:34PM +0300, Andy Shevchenko wrote: > > > On Wed, Sep 27, 2023 at 09:49:35PM +0800, Kent Gibson wrote: > > > > On Wed, Sep 27, 2023 at 03:17:06PM +0300, Andy Shevchenko wrote: > > > > > On Wed, Sep 27, 2023 at 09:32:11AM +0800, Kent Gibson wrote: > > ... > > > > > > Yet, it opens a way to scale this in case we might have v3 ABI that let's say > > > > > allows to work with 512 GPIOs at a time. With your code it will be much harder > > > > > to achieve and see what you wrote about maintenance (in that case). > > > > > > > > v3 ABI?? libgpiod v2 is barely out the door! > > > > Do you have any cases where 64 lines per request is limiting? > > > > > > IIRC it was SO question where the OP asks exactly about breaking the 64 lines > > > limitation in the current ABI. > > > > > > > If that sort of speculation isn't premature optimisation then I don't know > > > > what is. > > > > > > No, based on the real question / discussion, just have no link at hand. > > > But it's quite a niche, I can agree. > > > > Let me know if you find a ref to that discussion - I'm curious. > > Here it is (read comments as well): > https://stackoverflow.com/questions/76307370/control-gpio-from-linux-userspace-with-linux-gpio-h > That question looks to me to be confusing how many GPIOs can be requested per request (64) and in total (effectively unlimited) - thinking they are the same. That could be due to their desire to use the gpiod_chip_get_all_lines() convenience function with a chip with more than 64 lines, rather than because they have an actual need for the lines to be managed in a single request. So that doesn't look like a genuine use case to me - just a "what if I want to do X" question. Certainly not something that would warrant a v3 ABI. Cheers, Kent.