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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 C57A8C43461 for ; Mon, 7 Sep 2020 17:49:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9CCD4208C7 for ; Mon, 7 Sep 2020 17:49:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729437AbgIGRtJ (ORCPT ); Mon, 7 Sep 2020 13:49:09 -0400 Received: from mga05.intel.com ([192.55.52.43]:42086 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729109AbgIGMj1 (ORCPT ); Mon, 7 Sep 2020 08:39:27 -0400 IronPort-SDR: WBEeyuFP8hGcnGsYKszVJMrEVm9/hhP4MDtGgH+RcJ3+i9c6cGVDKB5VispU5Masx/ZkLI2FqZ iizPQrDHofpg== X-IronPort-AV: E=McAfee;i="6000,8403,9736"; a="242811803" X-IronPort-AV: E=Sophos;i="5.76,401,1592895600"; d="scan'208";a="242811803" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2020 05:38:43 -0700 IronPort-SDR: b9BfZlr40QZ2qISx/JXwCtkBAzS5PgLGV5xflcnOM8vMWXear5QSlnH4ccfPIOpexgx7jr18OP bYmVrfDS4+yA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,401,1592895600"; d="scan'208";a="333151425" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga008.jf.intel.com with ESMTP; 07 Sep 2020 05:38:40 -0700 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kFGPt-00Ewye-H3; Mon, 07 Sep 2020 15:38:37 +0300 Date: Mon, 7 Sep 2020 15:38:37 +0300 From: Andy Shevchenko To: Bartosz Golaszewski Cc: Randy Dunlap , Bartosz Golaszewski , Linus Walleij , Jonathan Corbet , Mika Westerberg , Kent Gibson , linux-gpio , linux-doc , LKML , ACPI Devel Maling List , Greg Kroah-Hartman Subject: Re: [PATCH 23/23] Documentation: gpio: add documentation for gpio-mockup Message-ID: <20200907123837.GG1891694@smile.fi.intel.com> References: <20200904154547.3836-1-brgl@bgdev.pl> <20200904154547.3836-24-brgl@bgdev.pl> <26ea1683-da8f-30e7-f004-3616e96d56b3@infradead.org> <20200907095932.GU1891694@smile.fi.intel.com> <20200907115310.GA1891694@smile.fi.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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 07, 2020 at 02:06:15PM +0200, Bartosz Golaszewski wrote: > On Mon, Sep 7, 2020 at 1:53 PM Andy Shevchenko > wrote: > > On Mon, Sep 07, 2020 at 12:26:34PM +0200, Bartosz Golaszewski wrote: > > > On Mon, Sep 7, 2020 at 11:59 AM Andy Shevchenko > > > wrote: > > > > On Fri, Sep 04, 2020 at 08:15:59PM -0700, Randy Dunlap wrote: > > > > > On 9/4/20 8:45 AM, Bartosz Golaszewski wrote: ... > > > > > > +GPIO Testing Driver > > > > > > +=================== > > > > > > + > > > > > > +The GPIO Testing Driver (gpio-mockup) provides a way to create simulated GPIO > > > > > > +chips for testing purposes. There are two ways of configuring the chips exposed > > > > > > +by the module. The lines can be accessed using the standard GPIO character > > > > > > +device interface as well as manipulated using the dedicated debugfs directory > > > > > > +structure. > > > > > > > > > > Could configfs be used for this instead of debugfs? > > > > > debugfs is ad hoc. > > > > > > > > Actually sounds like a good idea. > > > > > > > > > > Well, then we can go on and write an entirely new mockup driver > > > (ditching module params and dropping any backwards compatibility) > > > because we're already using debugfs for line values. > > > > > > How would we pass the device properties to configfs created GPIO chips > > > anyway? Devices seem to only be created using mkdir. Am I missing > > > something? > > > > Same way how USB composite works, no? > > > > OK, so create a new chip directory in configfs, configure it using > some defined configfs attributes and then finally instantiate it from > sysfs? > > Makes sense and is probably the right way to go. Now the question is: > is it fine to just entirely remove the previous gpio-mockup? Since, for example, I never saw device property bindings for that driver I assume that it was never considered as an ABI, so feel free to hack it in either direction. > Should we > keep some backwards compatibility? I wouldn't probably spend time on this. > Should we introduce an entirely new > module and have a transition period before removing previous > gpio-mockup? Neither transition period. > Also: this is a testing module so to me debugfs is just fine. Is > configfs considered stable ABI like sysfs? But this one is a good question. I think ConfigFS is stricter than DebugFS, up to being an ABI. But never did myself such a thing, so would like to hear experienced developers. -- With Best Regards, Andy Shevchenko