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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D20B4C04E69 for ; Thu, 10 Aug 2023 21:43:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229677AbjHJVnO (ORCPT ); Thu, 10 Aug 2023 17:43:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230344AbjHJVnN (ORCPT ); Thu, 10 Aug 2023 17:43:13 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DCF112D44; Thu, 10 Aug 2023 14:43:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6DB6463AB5; Thu, 10 Aug 2023 21:43:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0062C433C8; Thu, 10 Aug 2023 21:43:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691703791; bh=5gfooN1WBDgyvFXuZxSLOiq5g3Z7icCet3KI5PB9gbU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ARaBNIhiB1lhQbxYjA0c8e78hYWMIBh9PTQ2W9BcCA/xx55IcPgYYcDuusRbrqkZD sLbpUho0+zjdh6E9dKlsebhS1r6ESCLfaqbrUpH8zbEo+eGoVqryQPDnYz97ka/wiu teuz9FVTJRC50QZK9J5iP3tuQEtyT4+BWwkMbIVcDZUb6tiQCNqVFEdjj7VK0OrBys gJBSL9Sg9NOSBq3MkaYrSy9ann6LW+Jx70SKyKwoQ6CtcjKJWw5pViRs7zNwmHHAtk +AVEB/7o4rTor3ooIyJzSrwS7a5S/+HG3jrwbNLB/uXWdPv3uu4fDo/eOeoVjKwwGB uLDDU6Sv2jqjw== Received: (nullmailer pid 1316675 invoked by uid 1000); Thu, 10 Aug 2023 21:43:09 -0000 Date: Thu, 10 Aug 2023 15:43:09 -0600 From: Rob Herring To: =?iso-8859-1?Q?N=EDcolas_F=2E_R=2E_A=2E?= Prado Cc: Frank Rowand , Shuah Khan , cocci@inria.fr, Mark Brown , Nicolas Palix , kernelci@lists.linux.dev, Julia Lawall , Bjorn Andersson , kernel@collabora.com, Guenter Roeck , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 0/2] Add a test to catch unprobed Devicetree devices Message-ID: <20230810214309.GA1226583-robh@kernel.org> References: <20230810202413.1780286-1-nfraprado@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230810202413.1780286-1-nfraprado@collabora.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Aug 10, 2023 at 04:23:49PM -0400, Nícolas F. R. A. Prado wrote: > > Regressions that cause a device to no longer be probed by a driver can > have a big impact on the platform's functionality, and despite being > relatively common there isn't currently any generic test to detect them. > As an example, bootrr [1] does test for device probe, but it requires > defining the expected probed devices for each platform. > > Given that the Devicetree already provides a static description of > devices on the system, it is a good basis for building such a test on > top. > > This series introduces a test to catch regressions that prevent devices > from probing. > > Patch 1 introduces a script to parse the kernel source using Coccinelle > and extract all compatibles that can be matched by a Devicetree node to > a driver. Patch 2 adds a kselftest that walks over the Devicetree nodes > on the current platform and compares the compatibles to the ones on the > list, and on an ignore list, to point out devices that failed to be > probed. > > A compatible list is needed because not all compatibles that can show up > in a Devicetree node can be used to match to a driver, for example the > code for that compatible might use "OF_DECLARE" type macros and avoid > the driver framework, or the node might be controlled by a driver that > was bound to a different node. > > An ignore list is needed for the few cases where it's common for a > driver to match a device but not probe, like for the "simple-mfd" > compatible, where the driver only probes if that compatible is the > node's first compatible. > > Even though there's already scripts/dtc/dt-extract-compatibles that does > a similar job, it didn't seem to find all compatibles, returning ~3k, > while Coccinelle found ~11k. Besides that, Coccinelle actually parses > the C files, so it should be a more robust solution than relying on > regexes. I just sent a patch[1] last week fixing missing a bunch. I only looked at the change in count of undocumented (by schema) though. In any case, I'm happy if we have a better solution, but really we should only have 1. So your script would need to replace the existing one. I'd be interested in a performance comparison. IME, coccinelle is fairly slow. Slower is okay to a point though. > > The reason for parsing the kernel source instead of relying on > information exposed by the kernel at runtime (say, looking at modaliases > or introducing some other mechanism), is to be able to catch issues > where a config was renamed or a driver moved across configs, and the > .config used by the kernel not updated accordingly. We need to parse the > source to find all compatibles present in the kernel independent of the > current config being run. I've been down this route. I had another implementation using gdb to extract all of_device_id objects from a built kernel, but besides the build time, it was really slow. Rob [1] https://lore.kernel.org/all/20230804190130.1936566-1-robh@kernel.org/