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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 CE9B3C433DB for ; Fri, 29 Jan 2021 01:56:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8712D64DFB for ; Fri, 29 Jan 2021 01:56:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231279AbhA2B4J (ORCPT ); Thu, 28 Jan 2021 20:56:09 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:11471 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229819AbhA2B4F (ORCPT ); Thu, 28 Jan 2021 20:56:05 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4DRgPT6BHQzjDFw; Fri, 29 Jan 2021 09:54:21 +0800 (CST) Received: from [10.40.166.221] (10.40.166.221) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Fri, 29 Jan 2021 09:55:11 +0800 Message-ID: <60136AFF.5080204@hisilicon.com> Date: Fri, 29 Jan 2021 09:55:11 +0800 From: Wei Xu User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Arnd Bergmann CC: Zhen Lei , Philipp Zabel , Rob Herring , linux-arm-kernel , devicetree , linux-kernel , Zhangfei Gao , Chen Feng , Manivannan Sadhasivam , "Mauro Carvalho Chehab" Subject: Re: [PATCH v3 2/4] arm64: dts: correct vendor prefix hisi to hisilicon References: <20201208124641.1787-1-thunder.leizhen@huawei.com> <20201208124641.1787-3-thunder.leizhen@huawei.com> <6010B6DE.4060202@hisilicon.com> <60135EBA.5040803@hisilicon.com> In-Reply-To: <60135EBA.5040803@hisilicon.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.40.166.221] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Arnd, On 2021/1/29 9:02, Wei Xu wrote: > Hi Arnd, > > On 2021/1/28 22:08, Arnd Bergmann wrote: >> On Wed, Jan 27, 2021 at 1:42 AM Wei Xu wrote: >>> On 2021/1/27 6:23, Arnd Bergmann wrote: >>>> On Tue, Dec 8, 2020 at 1:46 PM Zhen Lei wrote: >>>>> >>>>> The vendor prefix of "Hisilicon Limited" is "hisilicon", it is clearly >>>>> stated in "vendor-prefixes.yaml". >>>>> >>>>> Fixes: 35ca8168133c ("arm64: dts: Add dts files for Hisilicon Hi3660 SoC") >>>>> Fixes: dd8c7b78c11b ("arm64: dts: Add devicetree for Hisilicon Hi3670 SoC") >>>>> Signed-off-by: Zhen Lei >>>>> Cc: Chen Feng >>>>> Cc: Manivannan Sadhasivam >>>> >>>> I see this change in the pull request I got, but I'm a bit worried about the >>>> incompatible binding change. Wouldn't the correct path forward be to >>>> list both the correct and the incorrect properties, both in the dts file >>>> and in the driver that interprets the properties? >>> >>> Thanks for the comment! >>> The reset driver will look for "hisilicon" firstly and fall back to "hisi". >>> And the DTS is shipped with the driver together. >>> So I think there is no compatible issue here. >>> Please let me know if missed anything. Thanks! >> >> There are three things that can go wrong here, and this is only addressing >> one of them: > > Thanks for the detailed explanation! > >> >> 1. Updating the kernel on a machine with a dtb provided by the firmware >> is a problem if the new driver can not handle the old properties. This >> is correctly handled by the driver's fallback as soon as both trees >> are merged. > > Agreed and the driver has been merged into the v5.11-rc1. Sorry, I made a mistake. It has been merged into linux-next *not* the v5.11-rc1. > >> >> 2. Updating the dtb while running an older kernel is now broken since >> the driver can no longer read the property. This is less critical, but >> it does seem easy enough to work around here by leaving both >> properties in place. > > Yes, it is. > But if leaving both in place, the dtbs_check will report following warning again: > 'hisi,rst-syscon' does not match any of the regexes > > That is why leizhen changed the dtb. > Do you think it is OK to assume no one will use the new dtb with an older kernel? > >> >> 3. Bisecting through the git history across an incompatible change >> means you can run into broken commits. We try hard to avoid that >> if we are aware of a problem in advance. In this case it could be >> avoided by only merging the incompatible DT change in a following >> merge window after the driver change, or (better) by making it >> a backward-compatible change the same way as addressing 2. > > Yes, agreed. > And The DT change pull request is sent after the driver has been merged into v5.11-rc1. I can drop this patch and revert what I have changed in Mauro's following patch: "arm64: dts: hisilicon: hi3670.dtsi: add iomcu_rst" Then resend the pull request. And pick up this patch after the next merge window. Do you think is it OK? Thanks! Best Regards, Wei > > Really appreciate the detail you went to! > > Best Regards, > Wei > >> >> Arnd >> . >>