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=-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, 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 9526CC433B4 for ; Fri, 23 Apr 2021 17:00:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 682AA613C4 for ; Fri, 23 Apr 2021 17:00:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243638AbhDWRBU (ORCPT ); Fri, 23 Apr 2021 13:01:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243410AbhDWRAf (ORCPT ); Fri, 23 Apr 2021 13:00:35 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63E70C06134A for ; Fri, 23 Apr 2021 09:59:57 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id c3so15668951pfo.3 for ; Fri, 23 Apr 2021 09:59:57 -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=gQpml6LY7Prl7t7mfNrEKr4/YWo6h583YxpHTazji+I=; b=CMfq2qDcrTK2b1SFUCZl8F3ujYtBndOl2TMhPVrj4aH1E2I16NvaQzc19oDJszLfid CxLnqp0WutR5SYYS+P2vhIfJ5ZvXrO3Ohqsd1NUL+oqydpuFunPUrOiefBS12z2zrnRu Ald6Uf3EfWB4GFrknG3RhT9JTBAxtA0heuUEs= 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=gQpml6LY7Prl7t7mfNrEKr4/YWo6h583YxpHTazji+I=; b=JR/0Wy2wzr2wsaDK8zStl+lJLEK3YTMtpzYcInp8ZHLflBUVibpZ+k/4/QEu3QPLTa HoMa1hgm0uZjhL8NGGrkx/CHKOqZopba/YHA5qB8HzWGLoy6G/Lo/qjs5GPDUYSQh8eH srnoL2ILKSJ+QuWagm3/ucYpgTxVvEzt2BiDfscX/Fqhk4AXWdAYMA9klrThrOiDsVsg 589ypP8A+djZY8mA7L/cQP5Ozsj50sQuxAa6Ts/0gTdnXUiLRxVXga7jiGibgnmnxsyp /0ut2WvKlF38A3i9gy4qo9xW4BgBpMb6nBKn6HGwfTLKgpsD7n0hdkwjdpmdFeCjX+6G 6zsQ== X-Gm-Message-State: AOAM533NBIk5dDDpG5PUoe6Ms4noiCSvDitgDaw6Qplw+6QsjQ7LyAxY fgHlYiGV0S86nil1XK9FU32cEw== X-Google-Smtp-Source: ABdhPJzi7ZOtZAGEwKGcjvP+7f7f5ph/mFq4PXS32e6ikwdc72PRbTlZo2MGrZN8aOExRGcMm37eRw== X-Received: by 2002:a62:e80f:0:b029:263:951f:14fb with SMTP id c15-20020a62e80f0000b0290263951f14fbmr4754352pfi.63.1619197196935; Fri, 23 Apr 2021 09:59:56 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:6d86:663d:71f8:6a11]) by smtp.gmail.com with ESMTPSA id v8sm5123607pfm.128.2021.04.23.09.59.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Apr 2021 09:59:56 -0700 (PDT) From: Douglas Anderson To: Andrzej Hajda , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Sam Ravnborg , Wolfram Sang Cc: linux-arm-msm@vger.kernel.org, robdclark@chromium.org, Stanislav Lisovskiy , Stephen Boyd , Steev Klimaszewski , Linus W , Maarten Lankhorst , linux-i2c@vger.kernel.org, Bjorn Andersson , dri-devel@lists.freedesktop.org, Douglas Anderson , linux-kernel@vger.kernel.org Subject: [PATCH v5 15/20] i2c: i2c-core-of: Fix corner case of finding adapter by node Date: Fri, 23 Apr 2021 09:59:01 -0700 Message-Id: <20210423095743.v5.15.Ib7e3a4af2f3e2cb3bd8e4adbac3bcfc966f27791@changeid> X-Mailer: git-send-email 2.31.1.498.g6c1eba8ee3d-goog In-Reply-To: <20210423165906.2504169-1-dianders@chromium.org> References: <20210423165906.2504169-1-dianders@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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); -- 2.31.1.498.g6c1eba8ee3d-goog