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 B9305FA3743 for ; Tue, 1 Nov 2022 07:23:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229648AbiKAHXf (ORCPT ); Tue, 1 Nov 2022 03:23:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46850 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229457AbiKAHXf (ORCPT ); Tue, 1 Nov 2022 03:23:35 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A548413F9D; Tue, 1 Nov 2022 00:23:32 -0700 (PDT) Received: from canpemm500004.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4N1hHL5fpqzpW5G; Tue, 1 Nov 2022 15:19:58 +0800 (CST) Received: from [10.174.179.106] (10.174.179.106) by canpemm500004.china.huawei.com (7.192.104.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 1 Nov 2022 15:23:29 +0800 Subject: Re: [PATCH next v9 1/4] i2c: hisi: Add initial device tree support To: Andy Shevchenko CC: , , , , , , , , , , , , , , , , References: <20221029115937.179788-1-chenweilong@huawei.com> From: chenweilong Message-ID: Date: Tue, 1 Nov 2022 15:23:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.179.106] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500004.china.huawei.com (7.192.104.92) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 2022/10/31 23:42, Andy Shevchenko wrote: > On Mon, Oct 31, 2022 at 09:57:51AM +0800, chenweilong wrote: >> On 2022/10/31 6:01, Andy Shevchenko wrote: >>> On Sat, Oct 29, 2022 at 07:59:36PM +0800, Weilong Chen wrote: >>>> The HiSilicon I2C controller can be used on embedded platform, which >>>> boot from devicetree. >>> ... >>> >>>> +#include >>>> +#include >>> Why? >>> >>> ... >>> >>>> +#ifdef CONFIG_ACPI >>> Why? >>> >>> ... >>> >>>> +#ifdef CONFIG_OF >>> Why? >>> >>> ... >>> >>>> - .acpi_match_table = hisi_i2c_acpi_ids, >>>> + .acpi_match_table = ACPI_PTR(hisi_i2c_acpi_ids), >>> Why? >>> >>> ... >>> >>>> + .of_match_table = of_match_ptr(hisi_i2c_dts_ids), >>> Why of_match_ptr()? >> There's a lot of drivers use of_match_ptr/ACPI_PTR to protect the of_device_id and >> have explicit headers file references to linux/acpi.h or linux/of.h, such as >> drivers/media/platform/intel/pxa_camera.c, >> bluetooth/hci_intel.c,  >> platform/x86/intel/chtwc_int33fe.c, >> platform/x86/intel/pmc/core.c and so on. > We have a lot of the legacy or not-up-to-dated to all new kernel APIs code. > Does it justify not to use the new approach in the new contribution? > > ... > >> The acpi.h and of.h have a nice function or macro definition if CONFIG_OF/ACPI is not satisfy, >> for example: >> >> #define ACPI_PTR(_ptr)  (_ptr)  vs  #define ACPI_PTR(_ptr)  (NULL) >> >> and also a lot of 'static inline' function there. > And why do you need it? > > ... > >> Seems a good idea to remove all of them, the codes your noted may look a bit >> verbose there. But I think it is valuable for a driver and device ,telling >> users it support acpi boot or is it just embedded. > So, what do we gain here? > > (Fill the "Advantages of your code" section below) > > Disadvantages of your code: > - ugly ifdeffery which we usually do not appreciate > - in some cases it's good to have OF ID table on ACPI platforms (see what > PRP0001 trick is) > - use old approach for the compiler on how to avoid warnings of the static > variables being defined and not used (note, neither ACPI_PTR() nor > of_match_ptr() provides a new approach on that, so you have to amend them > first) > - as a side effect additional headers to be included that are used for 1% or > less of their capacity and slow down the compilation Thanks very much for your detailed explanation. By the way,  is it valuable to make a cleanup for the legacy not-up-to-dated drivers? There's lots of of_match_ptr or ACPI_PTR... Best Regards.