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 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 0A885C2D0A3 for ; Mon, 9 Nov 2020 19:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CBAE6206F1 for ; Mon, 9 Nov 2020 19:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730526AbgKITBs (ORCPT ); Mon, 9 Nov 2020 14:01:48 -0500 Received: from mga17.intel.com ([192.55.52.151]:32867 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbgKITBr (ORCPT ); Mon, 9 Nov 2020 14:01:47 -0500 IronPort-SDR: C5BHEpvy+eVQUntqxm3LXxBEJQyuTgInrcafQFIoRT/GSKSHlf5TEZvYwEDMStTSiBnGcQPAcz AUt4ukrqrzeA== X-IronPort-AV: E=McAfee;i="6000,8403,9800"; a="149703977" X-IronPort-AV: E=Sophos;i="5.77,464,1596524400"; d="scan'208";a="149703977" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2020 11:01:46 -0800 IronPort-SDR: mVqj0b7salhhAY1TlsagMbJd5HSsuyoA7wn9fxUgtGzkpn5v5qG+nYzSQlS1sCGAX+2AZAdtSd 27XxX9IojKhw== X-IronPort-AV: E=Sophos;i="5.77,464,1596524400"; d="scan'208";a="322550834" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2020 11:01:43 -0800 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kcCRB-005Gnb-7p; Mon, 09 Nov 2020 21:02:45 +0200 Date: Mon, 9 Nov 2020 21:02:45 +0200 From: Andy Shevchenko To: Lukasz Stelmach Cc: Dmitry Torokhov , "Rafael J. Wysocki" , Heikki Krogerus , Mika Westerberg , Linus Walleij , Ard Biesheuvel , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, Marek Szyprowski , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH v8 3/6] software node: implement reference properties Message-ID: <20201109190245.GL4077@smile.fi.intel.com> References: <20201109172435.GJ4077@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 Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Nov 09, 2020 at 07:18:37PM +0100, Lukasz Stelmach wrote: > It was <2020-11-09 pon 19:24>, when Andy Shevchenko wrote: > > On Mon, Nov 09, 2020 at 06:02:29PM +0100, Lukasz Stelmach wrote: > >> It was <2019-11-07 czw 20:22>, when Dmitry Torokhov wrote: ... > >> I am writing a piece that needs to provide a list of gpios to a > >> diriver. The above example looks like what I need. > > > > Nope. > > > > It mustn't be used for GPIOs or PWMs or whatever that either should come via > > lookup tables or corresponding firmware interface. > > May I ask why? I've read commit descriptions for drivers/base/swnode.c > and the discussion on lkml and I understand software nodes as a way to > provide (synthesize) a description for a device that is missing a > description in the firmware. Another use case seems to be to replace (in > the long run) platform data. That is what I am trying to use it for. Yes. Both are correct. They are simply not applicable for everything (it's not a silver bullet). > I want my device to be configured with either DT or software_nodes > created at run time with configfs. Okay. > My device is going to use GPIOs > described in the DT and it is going to be configured via configfs at run > time. How is this related to swnodes? Create GPIO lookup table. > I could use platform_data to pass structures from configfs but > software nodes would let me save some code in the device driver and use > the same paths for both static (DT) and dynamic (configfs) > configuration. > > Probably I have missed something and I will be greatful, if you tell me > where I can find more information about software nodes. There are few > users in the kernel and it isn't obvious for me how to use software > nodes properly. gpiod_add_lookup_table(). > >> At the moment the driver gets the list from fwnode/of_node. The list > >> contain references to phandles which get resolved and and the driver > >> ends up with a bunch of gpio descriptors. Great. > >> > >> This example looks nice but does the code that reads the reference from > >> the gpios property and returns a gpiod actually exist? If it doesn't, I > >> am willing to write it. > >> > >> At first glance it makes more sense to me to pass (struct gpiod_lookup > >> *) instead of (struct software_node *) and make gpiolib's gpiod_find() > >> accept lookup tables as parameter instead of searching the > >> gpio_lookup_list? Or do you think such temporary table should be > >> assembled from the above structure and then used in gpiod_find()? > >> > >> Any other suggestions on how to get a bunch of gpios (the description > >> for gpios is available in the devicetree) for a device described with a > >> software nodes? -- With Best Regards, Andy Shevchenko