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 E6EA7C56201 for ; Mon, 9 Nov 2020 21:20:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0BE4206ED for ; Mon, 9 Nov 2020 21:20:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730923AbgKIVTQ (ORCPT ); Mon, 9 Nov 2020 16:19:16 -0500 Received: from mga12.intel.com ([192.55.52.136]:36683 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730902AbgKIVTP (ORCPT ); Mon, 9 Nov 2020 16:19:15 -0500 IronPort-SDR: 32BWqyAfq9NvJhEYKIgKY6JAX+ap190LxHT6a/hqF+Wj8fQhL4JF04lnd5Qdm8SQ1Cl5A5RPMG xliGMOkygwKQ== X-IronPort-AV: E=McAfee;i="6000,8403,9800"; a="149153800" X-IronPort-AV: E=Sophos;i="5.77,464,1596524400"; d="scan'208";a="149153800" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2020 13:19:14 -0800 IronPort-SDR: 7ZE/xk+pL6sDX8Z7U8m1ioz1eTOhBAKlEP8/Q0D/uDPaccZv2R+03Pzx3FC4cu5oBziJKQTkhh DvjIbSUm3mog== X-IronPort-AV: E=Sophos;i="5.77,464,1596524400"; d="scan'208";a="529505748" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2020 13:19:11 -0800 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kcEaD-005Ilt-FZ; Mon, 09 Nov 2020 23:20:13 +0200 Date: Mon, 9 Nov 2020 23:20:13 +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: <20201109212013.GN4077@smile.fi.intel.com> References: <20201109190245.GL4077@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 08:47:14PM +0100, Lukasz Stelmach wrote: > It was <2020-11-09 pon 21:02>, when Andy Shevchenko wrote: > > 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: ... > > 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(). > > > > Yes, that is exactly what my POC code does now. But having a lookup > table together with the rest of the device structures has several > advantages. > > 1) The device may be hotpluggable and there is no > gpiod_remove_lookup_table(). % git grep -n -w gpiod_remove_lookup_table Or I did get it wrong? Did you mean that the removal is not being called? > 2) Having the lookup table allocated and managed together with the rest > of the device seems like a better way to go than on gpio_lookup_list. Nice, what are you going to do with the rest of lookup tables (PWM, regulators, etc)? If you convert, convert them all at least. > 3) As of now I've got a minor issue with device naming. I need to set > dev_id of the table before the device is ready and only after it is > ready, its name is set (in the hotpluggable use case). Hotpluggable devices are very much supported by ACPI assistance. DT I have heard has overlays. What's the issue? > 4) Because no other devices would use this lookup table "publishing" it > rather than keeping together with the device seems at least slightly > odd. > > When the lookup table is attached to the devices and can be passed > around the final lookup can be done with a function like > > static struct gpio_desc *gpiod_find_from_table(struct device *dev, > const char *con_id, unsigned int idx, > unsigned long *flags, struct gpiod_lookup *table) Something sounds fishy about your case. Why do you need to have board code / platform data in the first place? Sorry, but I didn't get why you should reconstruct DT (or ACPI) at run-time without using proper framework / feature (overlays)? > >>>> 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