From patchwork Fri Apr 16 22:39:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 422712 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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 35A73C43461 for ; Fri, 16 Apr 2021 22:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20B8A613C0 for ; Fri, 16 Apr 2021 22:41:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235138AbhDPWl5 (ORCPT ); Fri, 16 Apr 2021 18:41:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235239AbhDPWll (ORCPT ); Fri, 16 Apr 2021 18:41:41 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0DACC061574 for ; Fri, 16 Apr 2021 15:41:16 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id k23-20020a17090a5917b02901043e35ad4aso17167292pji.3 for ; Fri, 16 Apr 2021 15:41:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=G1oK3A+M8fg+nmJCwN6uSqjhfKVKHBhUTiK9rrQlAS4=; b=bCeuEmR3HjXaHM41yzCpBTsW5gkiZWfz+buTmvLCoA3npH8nKGoWLVRFtmpaCOeNJv BMKH1h0fbC4DBaiaaLumGYJPd1GONx5InTjlGMDSJPKVKkmdgRdG0VztUjk+WywnCBvC OorkdjY52CQ8xbqIbH26D7ORN0pySvgdVIsRI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=G1oK3A+M8fg+nmJCwN6uSqjhfKVKHBhUTiK9rrQlAS4=; b=MmJgGCDdYFHsJttOilbFYIGS7ADZB1fcvn0SAOTQREMYD2RqB+sQKuTRH8ytx5UfEO QMthxf+NQeijz6vPXKVPFI94CrtpC8jAdo+0GjZfmpXgrzI3VnKWGrmX/265tsXuoU4M 65R+nzsNJ+yJckmECMdCJqekTLb50h2zIDoVmT3QOnWifSYJ4wNNRpb2a/EJAYXSZHRi eJ/nzjfonpxVoQ3pKyqsBPvR4uBDG7/yfZr/6cioEQgyVXkQ8KOj2OS/idBFUmUl0JNT XrhzgtaTH5TlpZVOBqGjRYC19m1miX0W/SPYgREwAvFhjDSoZaHbUPtF5hjm6RQ/bCpx QXnA== X-Gm-Message-State: AOAM530PkS6FimHlg9s6rKSmIhFMXNoCInPht+jcIELpAXba4x5V6WHH LX37UkivEX4vXwHu81WR0cuD7Q== X-Google-Smtp-Source: ABdhPJy6EH6g0mXqfXc8j8Oj2eoiQmlxQ4rGLqmYwpa2F46snG4cU2uBdupfef6ToF02aiZj4Q8Osg== X-Received: by 2002:a17:902:c40c:b029:ea:af9e:b123 with SMTP id k12-20020a170902c40cb02900eaaf9eb123mr11667608plk.30.1618612876151; Fri, 16 Apr 2021 15:41:16 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:dc8a:c9d0:aa5b:5386]) by smtp.gmail.com with ESMTPSA id r6sm5633659pgp.64.2021.04.16.15.41.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Apr 2021 15:41:15 -0700 (PDT) From: Douglas Anderson To: Andrzej Hajda , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Sam Ravnborg , Wolfram Sang Cc: Stephen Boyd , robdclark@chromium.org, Maarten Lankhorst , Stanislav Lisovskiy , Steev Klimaszewski , Bjorn Andersson , linux-arm-msm@vger.kernel.org, Linus W , Douglas Anderson , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 21/27] i2c: i2c-core-of: Fix corner case of finding adapter by node Date: Fri, 16 Apr 2021 15:39:44 -0700 Message-Id: <20210416153909.v4.21.Ib7e3a4af2f3e2cb3bd8e4adbac3bcfc966f27791@changeid> X-Mailer: git-send-email 2.31.1.368.gbe11c130af-goog In-Reply-To: <20210416223950.3586967-1-dianders@chromium.org> References: <20210416223950.3586967-1-dianders@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org The of_find_i2c_adapter_by_node() could end up failing to find an adapter in certain conditions. Specifically it's possible that of_dev_or_parent_node_match() could end up finding an I2C client in the list and cause bus_find_device() to stop early even though an I2C adapter was present later in the list. Let's move the i2c_verify_adapter() into the predicate function to prevent this. Now we'll properly skip over the I2C client and be able to find the I2C adapter. This issue has always been a potential problem if a single device tree node could represent both an I2C client and an adapter. I believe this is a sane thing to do if, for instance, an I2C-connected DP bridge chip is present. The bridge chip is an I2C client but it can also provide an I2C adapter (DDC tunneled over AUX channel). We don't want to have to create a sub-node just so a panel can link to it with the "ddc-i2c-bus" property. I believe that this problem got worse, however, with commit e814e688413a ("i2c: of: Try to find an I2C adapter matching the parent"). Starting at that commit it would be even easier to accidentally miss finding the adapter. Signed-off-by: Douglas Anderson Reviewed-by: Bjorn Andersson --- This commit is sorta just jammed into the middle of my series. It has no dependencies on the earlier patches in the series and I think it can land independently in the i2c tree. Later patches in the series won't work right without this one, but they won't crash. If we can't find the i2c bus we'll just fall back to the hardcoded panel modes which, at least today, all panels have. I'll also note that part of me wonders if we should actually fix this further to run two passes through everything: first look to see if we find an exact match and only look at the parent pointer if there is no match. I don't currently have a need for that and it's a slightly bigger change, but it seems conceivable that it could affect someone? (no changes since v1) drivers/i2c/i2c-core-of.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c index 3ed74aa4b44b..de0bf5fce3a2 100644 --- a/drivers/i2c/i2c-core-of.c +++ b/drivers/i2c/i2c-core-of.c @@ -124,6 +124,14 @@ static int of_dev_or_parent_node_match(struct device *dev, const void *data) return 0; } +static int of_i2c_adapter_match(struct device *dev, const void *data) +{ + if (!of_dev_or_parent_node_match(dev, data)) + return 0; + + return !!i2c_verify_adapter(dev); +} + /* must call put_device() when done with returned i2c_client device */ struct i2c_client *of_find_i2c_device_by_node(struct device_node *node) { @@ -146,18 +154,13 @@ EXPORT_SYMBOL(of_find_i2c_device_by_node); struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node) { struct device *dev; - struct i2c_adapter *adapter; dev = bus_find_device(&i2c_bus_type, NULL, node, - of_dev_or_parent_node_match); + of_i2c_adapter_match); if (!dev) return NULL; - adapter = i2c_verify_adapter(dev); - if (!adapter) - put_device(dev); - - return adapter; + return to_i2c_adapter(dev); } EXPORT_SYMBOL(of_find_i2c_adapter_by_node);