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 AC53CE7849A for ; Mon, 2 Oct 2023 09:42:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236212AbjJBJmz (ORCPT ); Mon, 2 Oct 2023 05:42:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236214AbjJBJmx (ORCPT ); Mon, 2 Oct 2023 05:42:53 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC03391; Mon, 2 Oct 2023 02:42:47 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id d9443c01a7336-1c60a514f3aso113957465ad.3; Mon, 02 Oct 2023 02:42:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696239767; x=1696844567; 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=FKWths37TuzuxqmK8rBu5qlLw0gJAvBT78PBFmf+dIk=; b=bOZpgJjAnJv5A4a+wEUKazFqnbBkAonWC/ub0eyK/omjqx5sP3vACWMFW/KfcTl027 HMCzspYzefJ5m8LiUELGEq0RnKu+622nDG1EOE6+giH1QrR+0So8XUEkRT4ofPcXrPrH +9nNJ/UcFFQVpIfJKzjxrw+Sk+cvuuqUevIQmWL+zB2ckmEnEsiYFMMMuVtTczy3UlDG xU9TJAtLpNbrmujcOvXnezE/rR2pXNJu8cjnGhy6lMXiuxa+mOUQGJyAkcoUcil5E1Ue iqriVqUybQFuF04gXWfCQma8KaZhwy5WV9jrRU3w6VJiehD5hXjGDc4Tt6odOIo46CZ0 GFZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696239767; x=1696844567; 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=FKWths37TuzuxqmK8rBu5qlLw0gJAvBT78PBFmf+dIk=; b=qCQERiumSQ9hRKBPNj10EAYM/ujOM20NAvc0LZMv7oMtIW1m2zqOlhw7jvdff95v7P OkmgXzD446ZkPeLoyRa4UpIyFKZa4HAKZmJaT1pINobaTGNayFr45gOuC8gFRneLPKal Wd3Qfqp5UEBcLlyVPY3niaY5kkAD3/ir+DKLbc/+h8DlVlq9ORrzXp07/x8cqE9LFTeU Q3mBw953HOO8Lv5TWovhJwaXtSA2s806oZkLw90bCATi6RR8sn6PziQ3lI88JgQuLvMh HroPN/fkISHhvHwyoWB/0vDcHMCLsuQ+byLkTXSNrvyy4pfeS++kz+FxMhUbWiMoEFM7 4V1A== X-Gm-Message-State: AOJu0YyVC6aqKhkHxBj6kKl2IPfeWv4ajd1sLAcxCjILUE8pS21LfcIf jHrVMQTc/V3r7Z6AxZtCPItkDgSFvBCgPw== X-Google-Smtp-Source: AGHT+IGJRJII6BjYEQve6vgOr3S4LQS11bujKYeGSJcS7jCV7mIKL7MxFT3lrUmNtDNzIvbuu1uF2A== X-Received: by 2002:a17:902:d2ce:b0:1c3:ed30:ce0a with SMTP id n14-20020a170902d2ce00b001c3ed30ce0amr14783738plc.19.1696239766662; Mon, 02 Oct 2023 02:42:46 -0700 (PDT) Received: from sol ([118.209.204.34]) by smtp.gmail.com with ESMTPSA id jj7-20020a170903048700b001c73701bd17sm7901033plb.4.2023.10.02.02.42.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 02:42:46 -0700 (PDT) Date: Mon, 2 Oct 2023 17:42:39 +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 12:32:22PM +0300, Andy Shevchenko wrote: > On Mon, Oct 02, 2023 at 05:25:05PM +0800, Kent Gibson wrote: > > 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. > > Sure, and I'm not talking about v3 ABI to go for, see the word "might" in my > reply in the first paragraph of this message. > Ok, so your original point was pure speculation. Cheers, Kent.