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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 54B74C433E1 for ; Mon, 29 Jun 2020 20:49:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F18C206C0 for ; Mon, 29 Jun 2020 20:49:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730590AbgF2Utd (ORCPT ); Mon, 29 Jun 2020 16:49:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731487AbgF2TNk (ORCPT ); Mon, 29 Jun 2020 15:13:40 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CA57C0076FC; Mon, 29 Jun 2020 04:26:43 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 6C20C2A2236 Subject: Re: [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent To: Chanwoo Choi , Marc Zyngier Cc: =?UTF-8?Q?Heiko_St=c3=bcbner?= , MyungJoo Ham , Kyungmin Park , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kernel-team@android.com, "stable@vger.kernel.org" References: <20200622152824.1054946-1-maz@kernel.org> <784808d7-8943-44ab-f15a-34821e6d4d5f@samsung.com> <87tuyue142.wl-maz@kernel.org> <3de68490-d788-e416-dd5f-d4d6e7eca61a@collabora.com> <154fe5b6-6a05-c2b7-3014-2f7b9c2049f9@samsung.com> From: Enric Balletbo i Serra Message-ID: <267623b3-9fc5-886e-3554-b86fa1e57ccb@collabora.com> Date: Mon, 29 Jun 2020 13:26:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <154fe5b6-6a05-c2b7-3014-2f7b9c2049f9@samsung.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hi Chanwoo, On 29/6/20 13:29, Chanwoo Choi wrote: > Hi Enric and Mark, > > On 6/29/20 8:05 PM, Enric Balletbo i Serra wrote: >> Hi Chanwoo and Marc, >> >> On 29/6/20 13:09, Chanwoo Choi wrote: >>> Hi Enric, >>> >>> Could you check this issue? Your patch[1] causes this issue. >>> As Marc mentioned, although rk3399-dmc.c handled 'rockchip,pmu' >>> as the mandatory property, your patch[1] didn't add the 'rockchip,pmu' >>> property to the documentation. >>> >> >> I think the problem is that the DT binding patch, for some reason, was missed >> and didn't land. The patch seems to have all the required reviews and acks. >> >> https://patchwork.kernel.org/patch/10901593/ >> >> Sorry because I didn't notice this issue when 9173c5ceb035 landed. And thanks >> for fixing the issue. > > If the 'rockchip,pmu' propery is mandatory, instead of Mark's patch, > we better to require the merge of patch[1] to DT maintainer. > > [1] https://patchwork.kernel.org/patch/10901593/ > Give me some time to double check, because I think that at this point, is needed on some devices with old firmware but not now. It's been a while since I worked on this, but I suspect that being optional is the right way. Maybe Heiko, who IIRC worked on TF-A has a more clear thought on this? Thanks, Enric >> >> Best regards, >> Enric >> >>> [1] 9173c5ceb035 ("PM / devfreq: rk3399_dmc: Pass ODT >>> and auto power down parameters to TF-A.") >>> >>> >>> On 6/29/20 5:18 PM, Marc Zyngier wrote: >>>> Hi Chanwoo, >>>> >>>> On Mon, 29 Jun 2020 03:43:37 +0100, >>>> Chanwoo Choi wrote: >>>>> >>>>> Hi Marc, >>>>> >>>>> On 6/23/20 12:28 AM, Marc Zyngier wrote: >>>> >>>> [...] >>>> >>>>> It looks good to me. But, I think that it is not necessary >>>>> fully kernel panic log about NULL pointer. It is enoughspsp >>>>> just mentioning the NULL pointer issue without full kernel panic log. >>>> >>>> I personally find the backtrace useful as it allows people with the >>>> same issue to trawl the kernel log and find whether it has already be >>>> fixed upstream. But it's only me, and I'm not attached to it. >>>> >>>>> So, how about editing the patch description as following or others simply? >>>>> and we need to add 'stable@vger.kernel.org' to Cc list for applying it >>>>> to stable branch. >>>> >>>> Looks good to me. >>>> >>>>> >>>>> >>>>> PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent >>>>> >>>>> Booting a recent kernel on a rk3399-based system (nanopc-t4), >>>>> equipped with a recent u-boot and ATF results in the kernel panic >>>>> about NULL pointer issue. >>>> >>>> nit: "results in a kernel panic on dereferencing a NULL pointer". >>>> >>>>> >>>>> This turns out to be due to the rk3399-dmc driver looking for >>>>> an *undocumented* property (rockchip,pmu), and happily using >>>>> a NULL pointer when the property isn't there. >>>>> >>>>> Instead, make most of what was brought in with 9173c5ceb035 >>>>> ("PM / devfreq: rk3399_dmc: Pass ODT and auto power down parameters >>>>> to TF-A.") conditioned on finding this property in the device-tree, >>>>> preventing the driver from exploding. >>>>> >>>>> Fixes: 9173c5ceb035 ("PM / devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A.") >>>>> Signed-off-by: Marc Zyngier >>>>> Signed-off-by: Chanwoo Choi >>>> >>>> >>>> Note that the biggest issue is still there: the driver is using an >>>> undocumented property, and this patch is just papering over it. >>>> Since I expect this property to be useful for something, it would be >>>> good for whoever knows what it does to document it. >>> >>> Hi Marc, >>> >>> You are right. We have to do two step: >>> 1. Add missing explanation of 'rockchip,pmu' property to dt-binding document >>> 2. If possible, add 'rockchip,pmu' property node to rk3399_dmc dt node. >>> >>> When I tried to find usage example of 'rockchip,pmu' property, >>> I found them as following: The 'rockchip,pmu' property[2] indicates >>> 'PMU (Power Management Unit)'. >>> >>> $ grep -rn "rockchip,pmu" arch/arm64/boot/dts/ >>> arch/arm64/boot/dts/rockchip/px30.dtsi:1211: rockchip,pmu = <&pmugrf>; >>> arch/arm64/boot/dts/rockchip/rk3399.dtsi:1909: rockchip,pmu = <&pmugrf>; >>> arch/arm64/boot/dts/rockchip/rk3368.dtsi:807: rockchip,pmu = <&pmugrf>; >>> >>> [2] the description of 'rockchip,pmu' property >>> - https://protect2.fireeye.com/url?k=e55f0ba3-b8384f85-e55e80ec-0cc47a31384a-d9c5f6b28aba9be6&q=1&u=https%3A%2F%2Felixir.bootlin.com%2Flinux%2Fv5.7.2%2Fsource%2FDocumentation%2Fdevicetree%2Fbindings%2Fpinctrl%2Frockchip%2Cpinctrl.txt%23L40 >>> >>> >>> If don't receive the any reply, I'll add as following: >>> >>> cwchoi00@chan-linux-pc:~/kernel/git.kernel/linux.chanwoo$ d >>> diff --git a/Documentation/devicetree/bindings/devfreq/rk3399_dmc.txt b/Documentation/devicetree/bindings/devfreq/rk3399_dmc.txt >>> index 0ec68141f85a..161e60ea874b 100644 >>> --- a/Documentation/devicetree/bindings/devfreq/rk3399_dmc.txt >>> +++ b/Documentation/devicetree/bindings/devfreq/rk3399_dmc.txt >>> @@ -18,6 +18,8 @@ Optional properties: >>> format depends on the interrupt controller. >>> It should be a DCF interrupt. When DDR DVFS finishes >>> a DCF interrupt is triggered. >>> +- rockchip,pmu: Phandle to the syscon managing the "pmu general >>> + register files". >>> >>> Following properties relate to DDR timing: >>> >>> >>> >> >> > >