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 0B588E784AF for ; Mon, 2 Oct 2023 09:32:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236105AbjJBJcc (ORCPT ); Mon, 2 Oct 2023 05:32:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236098AbjJBJcc (ORCPT ); Mon, 2 Oct 2023 05:32:32 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7409983; Mon, 2 Oct 2023 02:32:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696239149; x=1727775149; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=6GmsFUuqnSQcHUaemY2k1EPSCoudlb/4q0uxHkXHGLg=; b=a+bn3uPCR4UZrIpgag8O2X9jqtq65jffs4Agt000By1mIxViZmRgjVDT /SLKL4pvjnaDsgue9N55nkdwvdIo6FJtm5H7JFHUSZmcBI9lM/OS0pfRw wuVfPk7lCucuQe/Aoun/Uc/DFbIZqEY7W8qve2lTO9TXojYhPEsU9kPOu Lt1eDvgxdsBHZcXH8FF2klTRF3JnnS0lIYzLYe3F9XFodfao7BVolkyk3 vbSL8JsgaHRsAC7C5jLjgcFa6kw7BC4yEL8et7l5+ZkcCO6Vm1QHa58+u zvjUMcFcPg8YnnxAI0EZ/4mFO7ZflSdEVsVlPTQ83p17HwG+6EE6Ghu/Y g==; X-IronPort-AV: E=McAfee;i="6600,9927,10850"; a="382515680" X-IronPort-AV: E=Sophos;i="6.03,194,1694761200"; d="scan'208";a="382515680" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2023 02:32:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10850"; a="1081591076" X-IronPort-AV: E=Sophos;i="6.03,194,1694761200"; d="scan'208";a="1081591076" Received: from smile.fi.intel.com ([10.237.72.54]) by fmsmga005.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2023 02:32:25 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.97-RC0) (envelope-from ) id 1qnFHq-000000027Vr-1phY; Mon, 02 Oct 2023 12:32:22 +0300 Date: Mon, 2 Oct 2023 12:32:22 +0300 From: Andy Shevchenko To: Kent Gibson 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: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org 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. -- With Best Regards, Andy Shevchenko