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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3587BC43603 for ; Thu, 19 Dec 2019 02:50:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1F64227BF for ; Thu, 19 Dec 2019 02:50:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726824AbfLSCua (ORCPT ); Wed, 18 Dec 2019 21:50:30 -0500 Received: from mail-sz.amlogic.com ([211.162.65.117]:54507 "EHLO mail-sz.amlogic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726463AbfLSCua (ORCPT ); Wed, 18 Dec 2019 21:50:30 -0500 Received: from [10.28.19.135] (10.28.19.135) by mail-sz.amlogic.com (10.28.11.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1591.10; Thu, 19 Dec 2019 10:51:04 +0800 Subject: Re: [PATCH v5 2/4] dt-bindings: watchdog: add new binding for meson secure watchdog To: Rob Herring CC: Guenter Roeck , Martin Blumenstingl , Wim Van Sebroeck , Kevin Hilman , Neil Armstrong , Qianggui Song , , , Jianxin Pan , , Jian Hu , , , Jerome Brunet References: <1576153187-28378-1-git-send-email-xingyu.chen@amlogic.com> <1576153187-28378-3-git-send-email-xingyu.chen@amlogic.com> <1da513d7-20e1-726a-dcc4-952cbfbbe63a@amlogic.com> <20191218203404.GA2451@bogus> From: Xingyu Chen Message-ID: <2d762720-cb08-e72a-06e5-4096e211e34b@amlogic.com> Date: Thu, 19 Dec 2019 10:51:04 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20191218203404.GA2451@bogus> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB X-Originating-IP: [10.28.19.135] X-ClientProxiedBy: mail-sz.amlogic.com (10.28.11.5) To mail-sz.amlogic.com (10.28.11.5) Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org Hi, Rob On 2019/12/19 4:34, Rob Herring wrote: > On Wed, Dec 18, 2019 at 03:37:49PM +0800, Xingyu Chen wrote: >> Hi, Guenter Martin >> >> On 2019/12/16 21:30, Guenter Roeck wrote: >>> On 12/15/19 10:03 PM, Xingyu Chen wrote: >>>> Hi, Martin >>>> >>>> Sorry for the late reply. >>>> >>>> On 2019/12/13 4:05, Martin Blumenstingl wrote: >>>>> Hi Xingyu and Rob, >>>>> >>>>> On Thu, Dec 12, 2019 at 1:20 PM Xingyu Chen >>>>> wrote: >>>>> [...] >>>>>> +examples: >>>>>> +  - | >>>>>> +    watchdog { >>>>>> +          compatible = "amlogic,meson-sec-wdt"; >>>>>> +          timeout-sec = <60>; >>>>>> +    }; >>>>> in v3 of this patch Rob commented that there shouldn't be an OF node >>>>> if there are no additional properties >>>>> with timeout-sec there's now an additional property so my >>>>> understanding is that it's fine to have an OF node >>>> Your understanding is correct. >>>>> what I don't understand yet is where this node should be placed. >>>>> is it supposed to be a child node of the secure monitor node (for >>>>> which we already have a binding here: >>>>> Documentation/devicetree/bindings/firmware/meson/meson_sm.txt) or >>>>> where else would we place it inside the .dts? >>>> IMO,  Although the watchdog node need to reference the meson_sm >>>> node, there is no >>>> bus-like dependencies between the devices which the two nodes >>>> corresponding to. >>>> so i think that the watchdog node as child node of meson_sm maybe >>>> not appropriate. >>> The watchdog driver needs the meson SM's dt node, and it depends on the >>> existence >>> of that node. That seems enough of a relationship to warrant having it >>> as child note. >> Thanks for your reply, if i take the wdt node as child of secure monitor >> (sm), how should >> i register or find the wdt device ? >> >> I only think of the following three methods : >> 1). update the sm driver，and scan®ister wdt device when the sm driver >> probes(It is like i2c), but there >> are too many changes involved. > Just add of_platform_default_populate() call and clean-up calls. That's > not what I'd call 'too many changes'. Thanks for your guidance. > > >> 2). add "simple-bus" key string to compatible of sm node, and it will make >> the child node is registered as >> platform device, but it seems that the key string is not match current >> scene. > You previously said it's not a bus... > >> secure-monitor { >>     compatible = "amlogic,meson-gxbb-sm",  "simple-bus"; >> >>     watchdog { >>         compatible = "amlogic,meson-sec-wdt"; >>         timeout-sec = <60>; >>     } >> } >> >> 3).  don't register device, and find directly the watchdog node by using the >> of_* API in watchdog >> driver (Eg: linux-4.x/drivers/tee/optee/core.c) >> >> secure-monitor { >>     compatible = "amlogic,meson-gxbb-sm"; >> >>     watchdog { >>         compatible = "amlogic,meson-sec-wdt"; >>         timeout-sec = <60>; >>     } >> } >> >> The method 3 looks better for me, do you have a better suggestion ? Thanks >> >> BR >>> Guenter >>> >>> . >>> > . >