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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 52E7AC433FF for ; Tue, 30 Jul 2019 14:49:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 319FE206E0 for ; Tue, 30 Jul 2019 14:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730642AbfG3Otz (ORCPT ); Tue, 30 Jul 2019 10:49:55 -0400 Received: from mga12.intel.com ([192.55.52.136]:28859 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728722AbfG3Oty (ORCPT ); Tue, 30 Jul 2019 10:49:54 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Jul 2019 07:49:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,327,1559545200"; d="scan'208";a="323228335" Received: from rjwysock-mobl1.ger.corp.intel.com (HELO [10.249.145.48]) ([10.249.145.48]) by orsmga004.jf.intel.com with ESMTP; 30 Jul 2019 07:49:51 -0700 Subject: Re: [PATCH 1/2] drivers: base: swnode: link devices to software nodes To: Heikki Krogerus , Linus Walleij Cc: Dmitry Torokhov , "Enrico Weigelt, metux IT consult" , linux-input@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko References: <20190713075259.243565-1-dmitry.torokhov@gmail.com> <20190713075259.243565-2-dmitry.torokhov@gmail.com> <20190729120715.GA28600@kuha.fi.intel.com> <20190729131532.GA1201@penguin> <20190730115247.GK28600@kuha.fi.intel.com> From: "Rafael J. Wysocki" Organization: Intel Technology Poland Sp. z o. o., KRS 101882, ul. Slowackiego 173, 80-298 Gdansk Message-ID: Date: Tue, 30 Jul 2019 16:49:50 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190730115247.GK28600@kuha.fi.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/30/2019 1:52 PM, Heikki Krogerus wrote: > On Mon, Jul 29, 2019 at 03:15:32PM +0200, Dmitry Torokhov wrote: >> On Mon, Jul 29, 2019 at 03:07:15PM +0300, Heikki Krogerus wrote: >>> On Sat, Jul 13, 2019 at 12:52:58AM -0700, Dmitry Torokhov wrote: >>>> It is helpful to know what device, if any, a software node is tied to, so >>>> let's store a pointer to the device in software node structure. Note that >>>> children software nodes will inherit their parent's device pointer, so we >>>> do not have to traverse hierarchy to see what device the [sub]tree belongs >>>> to. >>>> >>>> We will be using the device pointer to locate GPIO lookup tables for >>>> devices with static properties. >>>> >>>> Signed-off-by: Dmitry Torokhov >>>> --- >>>> drivers/base/property.c | 1 + >>>> drivers/base/swnode.c | 35 ++++++++++++++++++++++++++++++++++- >>>> include/linux/property.h | 5 +++++ >>>> 3 files changed, 40 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/base/property.c b/drivers/base/property.c >>>> index 348b37e64944..3bc93d4b35c4 100644 >>>> --- a/drivers/base/property.c >>>> +++ b/drivers/base/property.c >>>> @@ -527,6 +527,7 @@ int device_add_properties(struct device *dev, >>>> if (IS_ERR(fwnode)) >>>> return PTR_ERR(fwnode); >>>> >>>> + software_node_link_device(fwnode, dev); >>>> set_secondary_fwnode(dev, fwnode); >>>> return 0; >>>> } >>>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c >>>> index 7fc5a18e02ad..fd12eea539b6 100644 >>>> --- a/drivers/base/swnode.c >>>> +++ b/drivers/base/swnode.c >>>> @@ -24,6 +24,9 @@ struct software_node { >>>> >>>> /* properties */ >>>> const struct property_entry *properties; >>>> + >>>> + /* device this node is associated with */ >>>> + struct device *dev; >>>> }; >>> Let's not do that! The nodes can be, and in many cases are, associated >>> with multiple devices. >> They do? Where? I see that set of properties can be shared between >> several devices, but when we instantiate SW node we create a new >> instance for device. This is also how ACPI and OF properties work; they >> not shared between devices (or, rather, the kernel creates distinct _and >> single_ devices for instance of ACPI or OF node). I do not think we want >> swnodes work differently from the other firmware nodes. > Having multiple devices linked to a single node is quite normal. Most > multifunctional devices will share a single node. The USB port devices > will share their node (if they have one) with any device that is > attached to them. Etc. > > If you want to check how this works with ACPI, then find > "physical_node" named files from sysfs. The ACPI node folders in sysfs > have symlinks named "physical_node" for every device they are bind > to. The first one is named just "physical_node", the second > "physical_node1", the third "physical_node2", and so on. > >>> Every device is already linked with the software node kobject, so >>> isn't it possible to simply walk trough those links in order to check >>> the devices associated with the node? >> No, we need to know the exact instance of a device, not a set of >> devices, because even though some properties can be shared, others can >> not. For example, even if 2 exactly same touch controllers in the system >> have "reset-gpios" property, they won't be the same GPIO for the both of >> them. > I don't think I completely understand the use case you had in mind for > this API, but since you planned to use it with the GPIO lookup tables, > I'm going to assume it's not needed after all. Let's replace those > with the references instead like I proposed in my reply to the 2/2 > patch. > > Linking a single device with a node like that is in any case not > acceptable nor possible. > I think I need to withdraw my ACK here at this point.