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 67EC5C433EF for ; Wed, 1 Dec 2021 13:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349426AbhLANoN (ORCPT ); Wed, 1 Dec 2021 08:44:13 -0500 Received: from mga07.intel.com ([134.134.136.100]:16329 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232866AbhLANoM (ORCPT ); Wed, 1 Dec 2021 08:44:12 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10184"; a="299847684" X-IronPort-AV: E=Sophos;i="5.87,278,1631602800"; d="scan'208";a="299847684" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Dec 2021 05:40:51 -0800 X-IronPort-AV: E=Sophos;i="5.87,278,1631602800"; d="scan'208";a="477541904" Received: from smile.fi.intel.com ([10.237.72.184]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Dec 2021 05:40:49 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1msPpp-000zsJ-Q2; Wed, 01 Dec 2021 15:39:45 +0200 Date: Wed, 1 Dec 2021 15:39:45 +0200 From: Andy Shevchenko To: Bartosz Golaszewski Cc: Kent Gibson , Linus Walleij , Shuah Khan , Geert Uytterhoeven , "open list:GPIO SUBSYSTEM" , Linux Kernel Mailing List , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v11 2/6] gpiolib: allow to specify the firmware node in struct gpio_chip Message-ID: References: <20211130154127.12272-1-brgl@bgdev.pl> <20211130154127.12272-3-brgl@bgdev.pl> 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 Wed, Dec 01, 2021 at 02:11:28PM +0100, Bartosz Golaszewski wrote: > On Tue, Nov 30, 2021 at 10:04 PM Bartosz Golaszewski wrote: > > > > On Tue, Nov 30, 2021 at 10:00 PM Andy Shevchenko > > wrote: > > > > > > On Tue, Nov 30, 2021 at 09:25:35PM +0100, Bartosz Golaszewski wrote: > > > > On Tue, Nov 30, 2021 at 5:15 PM Andy Shevchenko > > > > wrote: > > > > > > > > > > On Tue, Nov 30, 2021 at 04:41:23PM +0100, Bartosz Golaszewski wrote: > > > > > > Software nodes allow us to represent hierarchies for device components > > > > > > that don't have their struct device representation yet - for instance: > > > > > > banks of GPIOs under a common GPIO expander. The core gpiolib core > > > > > > > > > > core .. core ?! > > > > > > > > > > > however doesn't offer any way of passing this information from the > > > > > > drivers. > > > > > > > > > > > > This extends struct gpio_chip with a pointer to fwnode that can be set > > > > > > by the driver and used to pass device properties for child nodes. > > > > > > > > > > > > This is similar to how we handle device-tree sub-nodes with > > > > > > CONFIG_OF_GPIO enabled. > > > > > > > > > > Not sure I understand the proposal. Can you provide couple of (simplest) > > > > > examples? > > > > > > > > > > And also it sounds like reinventing a wheel. What problem do you have that you > > > > > need to solve this way? > > > > > > > > > > ... > > > > > > > > > > > +#if IS_ENABLED(CONFIG_OF_GPIO) > > > > > > + if (gc->of_node && gc->fwnode) { > > > > > > + pr_err("%s: tried to set both the of_node and fwnode in gpio_chip\n", > > > > > > + __func__); > > > > > > + return -EINVAL; > > > > > > + } > > > > > > +#endif /* CONFIG_OF_GPIO */ > > > > > > > > > > I don't like this. It seems like a hack right now. > > > > > > > > > > Is it possible to convert all GPIO controller drivers to provide an fwnode > > > > > rather than doing this? (I believe in most of the drivers we can drop > > > > > completely the of_node assignment). > > > > > > > > > > > > > Yes, it's definitely a good idea but I would be careful with just > > > > dropping the of_node assignments as callbacks may depend on them > > > > later. > > > > > > GPIO library does it for us among these lines: > > > > > > struct fwnode_handle *fwnode = gc->parent ? dev_fwnode(gc->parent) : NULL; > > > > > > of_gpio_dev_init(gc, gdev); <<< HERE! > > > acpi_gpio_dev_init(gc, gdev); > > > > > > /* > > > * Assign fwnode depending on the result of the previous calls, > > > * if none of them succeed, assign it to the parent's one. > > > */ > > > gdev->dev.fwnode = dev_fwnode(&gdev->dev) ?: fwnode; > > > > > > > Except that it doesn't and I noticed that when working on the > > subsequent patch. The child gpiochipX devices all had the parent's > > fwnode assigned as their primary fwnode and no secondary fwnode. > > > > Note that this driver doesn't use neither OF nor ACPI in which case > > gdev->dev has no fwnode and the parent's one is used. This patch > > addresses it. If you have a better idea, let me know. > > > > Bart > > Let me maybe rephrase the problem: currently, for GPIO devices > instantiating multiple banks created outside of the OF or ACPI > frameworks (e.g. instantiated manually and configured using a > hierarchy of software nodes with a single parent swnode and a number > of child swnodes representing the children), it is impossible to > assign firmware nodes other than the one representing the top GPIO > device to the gpiochip child devices. > > In fact if we want to drop the OF APIs entirely from gpiolib - this > would be the right first step as for gpio-sim it actually replaces the > gc->of_node = some_of_node; assignment that OF-based drivers do for > sub-nodes defining banks and it does work with device-tree (I verified > that too) thanks to the fwnode abstraction layer. I still don't see how you set up hierarchy of primary/secondary fwnodes. And I don't like this change. It seems it band-aids some issue with fwnode usage. What the easiest way to reproduce the issue with your series applied (without this change)? -- With Best Regards, Andy Shevchenko