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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham 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 5C801C433FF for ; Wed, 31 Jul 2019 22:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 262F3206B8 for ; Wed, 31 Jul 2019 22:17:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rnbl4GZg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727201AbfGaWRu (ORCPT ); Wed, 31 Jul 2019 18:17:50 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:39180 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731456AbfGaWRr (ORCPT ); Wed, 31 Jul 2019 18:17:47 -0400 Received: by mail-pf1-f202.google.com with SMTP id 6so44205500pfi.6 for ; Wed, 31 Jul 2019 15:17:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=fA8Osu/oMdHmE5xK0cud5jz6KCAzT5KFwSK5LVxi8is=; b=rnbl4GZgBHsU8D6w4X2hphOjRolmjAp6kw5tG1urgr4enZ8I0UDeF2kkufwOTRLUQt yN/+MH8/hdbZKWSDhQ4Y3XdzOK706JLRQYkr929TkNWs6vWqwEv/nH7LcQFu+59HeGIp SxDFwJbYemIPlemlAyr6b/rj/upIPShk4XXLBxraCwAzwjfqO+Oz0EVlB6XE0MFpkC22 XRJIyzvFrVme8jc4TSh4lWLjZyPHhdrc2Q+ehzroDiHf96gh6Y2i11rpin/lD1oiWSXH a0Ftf+aHdvgITk/3P53dv3BuEuAHJiRRnNEA/0QpqhWHRthXWrro4CZ7ezG+QkPGz0gb iMtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=fA8Osu/oMdHmE5xK0cud5jz6KCAzT5KFwSK5LVxi8is=; b=WdW1m2IAomE9ayFIXloiNS8lN0OZ4cIvNbFM2dlItksoaPS8TcspkNqQ/ioJ/WVbBI KyXh/KQdne1u3akrE6PiXAcQtttisGOyW65IC8LhYjpqycwELrmSlTs9qqtZeuXwzYmt TYIwjqiUuRNefnJy6GFanVooW7LEfZMbbHaloa2s8kHJ8hX90GJWIQtZoeLH1id+ABik oFt1FxKnBAVd8SAOXqZrclJbdN8ikpMzY7oI3lHCo7IBK+RLQ8f5JkFLt240p3U4cWwr 0Jk1MB5HuQr1S1PX4XD2jFwClyc2u42zHAXydUoc+hYYG9JxHAld1h8xCQi4/NUMl+f/ qKEQ== X-Gm-Message-State: APjAAAVC8Rzof3erotRkD7lvqMJa47+lTsCtL+MAoXfvdlNT7Apm4606 ucmjHTJAuLu9oRHqvGYDVY8PyQMPTczyulY= X-Google-Smtp-Source: APXvYqzIXnYVLFJgnPx+KLDzqKZgFks0IFD55XI8BZirhVe365cEU+SqYVghHTbw0lrYfI3tPRt1xCOwXeQFjw8= X-Received: by 2002:a63:1341:: with SMTP id 1mr8204047pgt.48.1564611466027; Wed, 31 Jul 2019 15:17:46 -0700 (PDT) Date: Wed, 31 Jul 2019 15:17:19 -0700 In-Reply-To: <20190731221721.187713-1-saravanak@google.com> Message-Id: <20190731221721.187713-7-saravanak@google.com> Mime-Version: 1.0 References: <20190731221721.187713-1-saravanak@google.com> X-Mailer: git-send-email 2.22.0.709.g102302147b-goog Subject: [PATCH v9 6/7] of/platform: Create device links for all child-supplier depencencies From: Saravana Kannan To: Rob Herring , Mark Rutland , Greg Kroah-Hartman , "Rafael J. Wysocki" , Frank Rowand Cc: Saravana Kannan , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, David Collins , kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A parent device can have child devices that it adds when it probes. But this probing of the parent device can happen way after kernel init is done -- for example, when the parent device's driver is loaded as a module. In such cases, if the child devices depend on a supplier in the system, we need to make sure the supplier gets the sync_state() callback only after these child devices are added and probed. To achieve this, when creating device links for a device by looking at its DT node, don't just look at DT references at the top node level. Look at DT references in all the descendant nodes too and create device links from the ancestor device to all these supplier devices. This way, when the parent device probes and adds child devices, the child devices can then create their own device links to the suppliers and further delay the supplier's sync_state() callback to after the child devices are probed. Example: In this illustration, -> denotes DT references and indentation represents child status. Device node A Device node B -> D Device node C -> B, D Device node D Assume all these devices have their drivers loaded as modules. Without this patch, this is the sequence of events: 1. D is added. 2. A is added. 3. Device D probes. 4. Device D gets its sync_state() callback. 5. Device B and C might malfunction because their resources got altered/turned off before they can make active requests for them. With this patch, this is the sequence of events: 1. D is added. 2. A is added and creates device links to D. 3. Device link from A to B is not added because A is a parent of B. 4. Device D probes. 5. Device D does not get it's sync_state() callback because consumer A hasn't probed yet. 5. Device A probes. 5. a. Devices B and C are added. 5. b. Device links from B and C to D are added. 5. c. Device A's probe completes. 6. Device D does not get it's sync_state() callback because consumer A has probed but consumers B and C haven't probed yet. 7. Device B and C probe. 8. Device D gets it's sync_state() callback because all its consumers have probed. 9. None of the devices malfunction. Signed-off-by: Saravana Kannan --- drivers/of/platform.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 6c9c8dcee912..36e25136e807 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -655,24 +655,35 @@ static bool of_link_property(struct device *dev, struct device_node *con_np, return done ? 0 : -ENODEV; } +static int __of_link_to_suppliers(struct device *dev, + struct device_node *con_np) +{ + struct device_node *child; + struct property *p; + bool done = true; + + for_each_property_of_node(con_np, p) + if (of_link_property(dev, con_np, p->name)) + done = false; + + for_each_child_of_node(con_np, child) + if (__of_link_to_suppliers(dev, child)) + done = false; + + return done ? 0 : -ENODEV; +} + static bool of_devlink; core_param(of_devlink, of_devlink, bool, 0); static int of_link_to_suppliers(struct device *dev) { - struct property *p; - bool done = true; - if (!of_devlink) return 0; if (unlikely(!dev->of_node)) return 0; - for_each_property_of_node(dev->of_node, p) - if (of_link_property(dev, dev->of_node, p->name)) - done = false; - - return done ? 0 : -ENODEV; + return __of_link_to_suppliers(dev, dev->of_node); } #ifndef CONFIG_PPC -- 2.22.0.709.g102302147b-goog