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 9F731EB64DD for ; Wed, 9 Aug 2023 12:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230393AbjHIMMU (ORCPT ); Wed, 9 Aug 2023 08:12:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231331AbjHIMMT (ORCPT ); Wed, 9 Aug 2023 08:12:19 -0400 Received: from email.cn (m218-171.88.com [110.43.218.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0A0A1982 for ; Wed, 9 Aug 2023 05:12:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=email.cn; s=dkim; h=Date:From:To; bh=YvdOL9C/iedM5DBNdd9VTjEevDzi7adrzeNuX +/2TmA=; b=b7dINqkxcXM7J04e2Wedlkv4IDUK/dRcit0PJ+bQoA+RE6SncbErN IPeNV5l8C0myTE0/U1HQxR14AH73x19jdYRzQTZqrSWGYOXjNSEQ38UlLlgLjw6/ 9TcuwI9EI2dh6o/K6tIIUMaZtfhka/mNPZiBFIAK3RHjPpLib9C+xE= Received: from localhost (unknown [119.3.119.18]) by v_coremail2-frontend-1 (Coremail) with SMTP id LCKnCgDnC4KBgtNkuPUVAA--.50580S3; Wed, 09 Aug 2023 20:11:46 +0800 (CST) Date: Wed, 9 Aug 2023 20:11:45 +0800 From: Liang Li To: Yicong Yang Cc: Barry Song <21cnbao@gmail.com>, Liang Li , yangyicong@hisilicon.com, will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, jonathan.cameron@huawei.com, linuxarm@huawei.com Subject: Re: [PATCH] perf/smmuv3: Add platform id table for module auto loading Message-ID: Reply-To: Liang Li References: <20230807122233.28563-1-yangyicong@huawei.com> <23fe3d9a-cb4d-3479-0581-eefec193bc72@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <23fe3d9a-cb4d-3479-0581-eefec193bc72@huawei.com> X-CM-TRANSID: LCKnCgDnC4KBgtNkuPUVAA--.50580S3 X-Coremail-Antispam: 1UD129KBjvJXoWxJrWUZF43XrW8CF43ZrWDurg_yoW8tw43pa y8GFy3K3yDJw1rCr92vw47XF1jkws7JFZ5XFn8Jr12v3s09Fy2vry3KayYk34Duwn5C3Wj vrWYqa4fG34FyaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUka1xkIjI8I6I8E6xAIw20EY4v20xvaj40_JFC_Wr1l8cAvFVAK 0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWUJVWUCwA2z4 x0Y4vE2Ix0cI8IcVCY1x0267AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv67AKxVWxJr0_GcWl 84ACjcxK6I8E87Iv6xkF7I0E14v26F4UJVW0owAS0I0E0xvYzxvE52x082IY62kv0487Mc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VCjz48v1sIEY20_Cr1UJr1lOx8S6xCaFVCjc4AY 6r1j6r4UM4x0Y48IcVAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x0262 8vn2kIc2xKxwCY1x0264kExVAvwVAq07x20xyl42xK82IYc2Ij64vIr41l42xK82IY6x8E rcxFaVAv8VWxJr1UJwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r 18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vI r41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr 1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvE x4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JjrJ5rUUUUU= X-Originating-IP: [119.3.119.18] X-CM-SenderInfo: 5oloxttqjwqvhpdlzhdfq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yicong, Thanks for your reply, On 2023-08-09 14:31, Yicong Yang wrote: > Hi Barry, Liang, > > On 2023/8/9 13:47, Barry Song wrote: > > On Wed, Aug 9, 2023 at 1:01 PM Liang Li wrote: > >> > >> On 2023-08-07 20:22, Yicong Yang wrote: > >>> From: Yicong Yang > >>> > >>> On ACPI based system the device is probed by the name directly. If the > >>> driver is configured as module it can only be loaded manually. Add the > >>> platform id table as well as the module alias then the driver will be > >>> loaded automatically by the udev or others once the device added. > >>> > >> > >> Please consider revise the long log to clearly express the purpose of the > >> changes in this patch: > >> > >> - What's the exact issue the patch is addressing > >> - Why the changes in this patch can fix the issue or make something working > >> - Consider impact of the changes introduced by this patch > >> > >> These info may help reviewers and maintainers .. and yourself on code merge. > > > > years ago, i found a good doc regarding this, > > https://wiki.archlinux.org/title/Modalias > > > > guess it is because /lib/modules/$(uname -r)/modules.alias fails to contain smmu > > driver without the MODULE_DEVICE_TABLE, isn't it, yicong？ > > Yes I think it's the reason. I didn't find summary in kernel docs for the modalias > as well as the uevent mechanism. Arch wiki has a well illustration for the modalias > and suse[1] describes how this is used by the udev for module auto loading. > > For my case I'm using a ACPI based arm64 server and after booting the arm_smmuv3_pmu.ko > is not auto loaded by the udevd since we aren't providing this information. In order > to support this we need to provide this MODULE_DEVICE_TABLE() when the smmu pmu added > as a platform device, then the userspace udev can know which module to load after the > device is added. > Then what's the purpose of the added '.id_table = ...' line in the previous patch ? Based on above clarification, the updated DEVICE_TABLE would update modalias as expected, right ? > [1] https://documentation.suse.com/sles/15-SP1/html/SLES-all/cha-udev.html#sec-udev-drivers > > Thanks. Regards. Liang Li