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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 8437CC00A89 for ; Fri, 30 Oct 2020 10:30:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3452B221EB for ; Fri, 30 Oct 2020 10:30:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726447AbgJ3KaG (ORCPT ); Fri, 30 Oct 2020 06:30:06 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:58086 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726437AbgJ3KaE (ORCPT ); Fri, 30 Oct 2020 06:30:04 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 57E141F45E58 Subject: Re: [PATCH v2 02/12] soc: mediatek: Add MediaTek SCPSYS power domains To: Nicolas Boichat Cc: lkml , Collabora Kernel ML , Fabien Parent , Matthias Brugger , Hsin-Yi Wang , Weiyi Lu , Matthias Brugger , linux-arm Mailing List , "moderated list:ARM/Mediatek SoC support" References: <20201001160154.3587848-1-enric.balletbo@collabora.com> <20201001160154.3587848-3-enric.balletbo@collabora.com> <2e6def0a-400c-836f-ef8b-c4fe6ac6c26e@collabora.com> From: Enric Balletbo i Serra Message-ID: <72dca621-ceb4-72ae-f340-c01474cb5b8d@collabora.com> Date: Fri, 30 Oct 2020 11:29:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nicolas, On 28/10/20 2:13, Nicolas Boichat wrote: > On Wed, Oct 28, 2020 at 12:25 AM Enric Balletbo i Serra > wrote: >> >> Hi Nicolas, >> >> On 27/10/20 1:19, Nicolas Boichat wrote: >>> Hi Enric, >>> >>> On Mon, Oct 26, 2020 at 11:17 PM Enric Balletbo i Serra >>> wrote: >>>> >>>> Hi Nicolas, >>>> >>>> Many thanks for looking at this. >>> >>> Thanks to you ,-) >>> >>> [snip] >>>>>> + if (id >= scpsys->soc_data->num_domains) { >>>>>> + dev_err_probe(scpsys->dev, -EINVAL, "%pOFn: invalid domain id %d\n", node, id); >>>>>> + return -EINVAL; >>>>>> + } >>>>>> + >>>>>> + domain_data = &scpsys->soc_data->domains[id]; >>>>>> + if (!domain_data) { >>>>> >>>>> Is that even possible at all? I mean, even if >>>>> scpsys->soc_data->domains is NULL, as long as id != 0, this will no >>>>> happen. >>>>> >>>> >>>> I think could happen with a bad DT definition. I.e if for the definition of the >>>> MT8173 domains you use a wrong value for the reg property, a value that is not >>>> present in the SoC data. It is unlikely if you use the defines but could happen >>>> if you hardcore the value. We cannot check this with the DT json-schema. >>> >>> I wasn't clear in my explanation, and looking further there is more >>> that looks wrong. >>> >>> This expression &scpsys->soc_data->domains[id] is a pointer to element >>> "id" of the array domains. So if you convert to integer arithmetic, >>> it'll be something like `(long)scpsys->soc_data->domains + >>> (sizeof(struct generic_pm_domain *)) * id`. The only way this can be >>> NULL is if scpsys->soc_data->domains pointer is NULL, which, actually, >>> can't really happen as it's the 5th element of a struct scpsys >>> structure `(long)scpsys->soc_data + offset_of(domains, struct scpsys) >>> + (sizeof(struct generic_pm_domain *)) * id`. >>> >>> I think what you mean is either: >>> domain_data = &scpsys->soc_data->domains[id]; >>> if (!*domain_data) >>> [but then domain_data type should be `struct generic_pm_domain **`? >> >> I think you're confusing the field `struct generic_pm_domain *domains[]`from the >> `struct scpsys` with `const struct scpsys_domain_data *domains` from `struct >> scpsys_soc_data`. My bad they have the same name, I should probably rename the >> second one as domain_info or domain_data to avoid that confusion. > > Oh, okay, get it, thanks for clarifying, I got myself confused indeed ,-P > > But, still, part of my integer arithmetics still holds... > > &scpsys->soc_data->domains[id] = (long)scpsys->soc_data->domains + > (sizeof(struct generic_pm_domain *)) * id. The only way domain_data > can be NULL is if scpsys->soc_data->domains pointer is NULL (it can't > be, really, assuming scpsys_soc_data structures are well defined) AND > id is 0. > > Now, if I understand what you want to check here. If a domain id is > not specified in scpsys_domain_data (e.g. if there is a gap in > MT8XXX_POWER_DOMAIN_YYY indices and if `id` points at one of those > gaps), you'll get an all-zero entry in domain_data. So maybe you can > just check that domain_data->sta_mask != 0? Would that be enough? (I > expect that sta_mask would always need to be set?) > Yes, that would be enough. I'll change for the next version. > But then again, are there ever gaps in MT8XXX_POWER_DOMAIN_YYY indices? > AFAIK, there is no gaps, but one could make gaps when filling that info. I still think is worth have this check although is "unlikely" to happen due an human error :-). I'll maintain for the next version, but I don't really care to remove it if all you prefer I remove it. Thanks, Enric >> >> >> diff --git a/drivers/soc/mediatek/mtk-pm-domains.h >> b/drivers/soc/mediatek/mtk-pm-domains.h >> index 7c8efcb3cef2..6ff095db8a27 100644 >> --- a/drivers/soc/mediatek/mtk-pm-domains.h >> +++ b/drivers/soc/mediatek/mtk-pm-domains.h >> @@ -56,7 +56,7 @@ struct scpsys_domain_data { >> }; >> >> struct scpsys_soc_data { >> - const struct scpsys_domain_data *domains; >> + const struct scpsys_domain_data *domain_data; >> int num_domains; >> int pwr_sta_offs; >> int pwr_sta2nd_offs; >> >> --- >> >> struct scpsys { >> ... >> const struct scpsys_soc_data *soc_data; >> ... >> struct generic_pm_domain *domains[]; >> } >> >> >> domain_data = &scpsys->soc_data->domain_data[id]; >> if (!domain_data) >> >> Thanks, >> Enric >> >> >>> Does your code compile with warnings enabled?] >>> or: >>> domain_data = scpsys->soc_data->domains[id]; >>> if (!domain_data) >>> [then the test makes sense] >>> >>> [snip] >>>