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 23F04C433E0 for ; Mon, 29 Jun 2020 19:14:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FE94206E9 for ; Mon, 29 Jun 2020 19:14:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730682AbgF2TOb (ORCPT ); Mon, 29 Jun 2020 15:14:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731795AbgF2TOY (ORCPT ); Mon, 29 Jun 2020 15:14:24 -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 F0433C061755; Mon, 29 Jun 2020 04:05:33 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id E26C72A2184 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> From: Enric Balletbo i Serra Message-ID: <3de68490-d788-e416-dd5f-d4d6e7eca61a@collabora.com> Date: Mon, 29 Jun 2020 13:05:28 +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: 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 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. 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://elixir.bootlin.com/linux/v5.7.2/source/Documentation/devicetree/bindings/pinctrl/rockchip,pinctrl.txt#L40 > > > 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: > > >