From patchwork Mon May 3 21:58:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 430701 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=-19.4 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, URIBL_BLOCKED, 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 B15BFC43462 for ; Mon, 3 May 2021 21:59:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C2AA613B3 for ; Mon, 3 May 2021 21:59:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbhECWAM (ORCPT ); Mon, 3 May 2021 18:00:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229721AbhECWAL (ORCPT ); Mon, 3 May 2021 18:00:11 -0400 Received: from mail-pg1-x532.google.com (mail-pg1-x532.google.com [IPv6:2607:f8b0:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15DF6C061574 for ; Mon, 3 May 2021 14:59:18 -0700 (PDT) Received: by mail-pg1-x532.google.com with SMTP id p12so4793018pgj.10 for ; Mon, 03 May 2021 14:59:18 -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=C70V1ep2OC0kZd3ksfbxSiRkqnQcxIJ5Zt5dguO6jEA=; b=ddABHDYPpcDSWspsVe5JjaRfWW2WGzybj41mDN4dyyhwjLnvgl8JpgEMRrm0zl8014 sghhgQqUZi2bnSITlK49Sqef/89J5Z0uzWa29w7OYowYEtVZghumEDiQhCbYWYhRuDeL 8Ga3xvrQTHc+QoTZKO6w2zXurJ7km4LRNn3M8= 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=C70V1ep2OC0kZd3ksfbxSiRkqnQcxIJ5Zt5dguO6jEA=; b=qs1ntV/yDiF9noBsj6jwZM1HicfzQrmAfjSoMRhoBQ9q8yp6pbjpzH9r9QHic0OL4c w7n4kD3lcd50Y/Za4J/lC0MaRr+hMtwf/BgEEkJ0UO5+W9WD/609KEa5uZGicxGm/u/q obnBjgoyDbtAR+Wzx0tl5ncXY6oKbC5mOhOl9h9aySBElCwdEXS80SMKkGm6sCfcLja5 rfMgJp1SWLXxL5vonqN9gOINkdtwOGgk61nup728/QWkk/pwEyu4rwOCTpj7+p6hfpKJ XOuMrJPfMleRIwKX7l0WuFBV5QDRhipkGxRvn8ZtQsscRSLgVnwGWQd1Sy7YFp9N3PV0 hHOw== X-Gm-Message-State: AOAM530jtXVRNeknKV7JpdFefyAf0GBczXE+pgsIgbh1sAKVlF6gUtky XiQNjj1VYfzAQBpHMRb2/vlMfA== X-Google-Smtp-Source: ABdhPJxCffXNMJSO10RrlyG4KuAU0sSx6Cz3Lg0v+K+XZhSsqwIjdP9TiZSAgQzu7azyCwAucvUELg== X-Received: by 2002:a17:90b:3684:: with SMTP id mj4mr958049pjb.50.1620079157449; Mon, 03 May 2021 14:59:17 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:a592:ac50:b17b:5c43]) by smtp.gmail.com with ESMTPSA id w1sm639186pgp.31.2021.05.03.14.59.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 May 2021 14:59:16 -0700 (PDT) From: Douglas Anderson To: Andrzej Hajda , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Sam Ravnborg , Wolfram Sang Cc: Lyude Paul , Steev Klimaszewski , Stephen Boyd , Bjorn Andersson , linux-arm-msm@vger.kernel.org, Stanislav Lisovskiy , Linus W , robdclark@chromium.org, Maarten Lankhorst , Thierry Reding , linux-i2c@vger.kernel.org, dri-devel@lists.freedesktop.org, Douglas Anderson , linux-kernel@vger.kernel.org Subject: [PATCH v6 1/5] i2c: i2c-core-of: Fix corner case of finding adapter by node Date: Mon, 3 May 2021 14:58:40 -0700 Message-Id: <20210503145750.v6.1.Ib7e3a4af2f3e2cb3bd8e4adbac3bcfc966f27791@changeid> X-Mailer: git-send-email 2.31.1.527.g47e6f16901-goog In-Reply-To: <20210503215844.2996320-1-dianders@chromium.org> References: <20210503215844.2996320-1-dianders@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@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 --- Later patches in this 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);