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Mon, 29 Jun 2020 21:01:07 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20200629120107epsmtip246ec2fee9326708f827b30a009d3db48~dAgXcx1352885228852epsmtip2e; Mon, 29 Jun 2020 12:01:07 +0000 (GMT) Subject: Re: [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent To: Enric Balletbo i Serra , 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" From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <566d2f93-b5ff-b583-3965-83d4b9188c36@samsung.com> Date: Mon, 29 Jun 2020 21:12:18 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <267623b3-9fc5-886e-3554-b86fa1e57ccb@collabora.com> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrCJsWRmVeSWpSXmKPExsWy7bCmri7LjZ9xBvv/S1msuX2I0eL/o9es Fju2i1icbXrDbnF51xw2i8+9Rxgtds45yWpxu3EFm8WCjY8YHTg9tu3exuqx4+4SRo9NqzrZ PPq2rGL02H5tHrPH501yAWxR2TYZqYkpqUUKqXnJ+SmZeem2St7B8c7xpmYGhrqGlhbmSgp5 ibmptkouPgG6bpk5QEcpKZQl5pQChQISi4uV9O1sivJLS1IVMvKLS2yVUgtScgosC/SKE3OL S/PS9ZLzc60MDQyMTIEKE7Iztn+5ylawTL9iXusv9gbGX6pdjJwcEgImEvNXb2TuYuTiEBLY wSgx68E5dgjnE6NEy7mzTBDOZ0aJaz+fAzkcYC0Nf6Hiuxgler6vZAIZJSTwnlFi4vciEFtY IF7iRssdVhBbRCBKov/jN7AGZoFJTBKTln0AS7AJaEnsf3GDDcTmF1CUuPrjMSOIzStgJ3H9 0hawoSwCqhIr3s0Es0UFwiRObmuBqhGUODnzCQvIQZwCjhJ/PgaDhJkFxCVuPZnPBGHLS2x/ OwfsNQmBHRwSJzoOsEI84CIx/SsvxPvCEq+Ob2GHsKUkXva3QdnVEitPHmGD6O1glNiy/wIr RMJYYv/SyeCAYBbQlFi/Sx8irCix8/dcRoi9fBLvvvZAreKV6GgTgihRlrj84C4ThC0psbi9 k20Co9IsJM/MQvLBLCQfzEJYtoCRZRWjWGpBcW56arFhgSlyXG9iBCdXLcsdjNPfftA7xMjE wXiIUYKDWUmE97P1tzgh3pTEyqrUovz4otKc1OJDjKbA4J3ILCWanA9M73kl8YamRsbGxhYm hmamhoZK4rxO1hfihATSE0tSs1NTC1KLYPqYODilGpjW+N7MFS38GxJxlO94uQYbVzzHzoUb hQ5/0/2/nWnDlV+2Ng/+fplz86DSdhnR+JpZDzbsWXD+g7Jn7Iwl5cn9h5SDEpLTNncZ+58N +7h1+29xud3beurudb3475Dy5Le+zKzm/8w+3cdkZv3fzPCB2/3wM+7HihbPts/8Ez1dWuzy scz+VXfuMhVqzzzad5TxJtNrhZZTv5trc3dZr/Tu+dbr8ujWuUbGz5P3mfKL6Z1Jm1O883GZ g8zNoIPhFbovbKfczll24tyf3g0ace8Dvv5gPBmRrbN48cWmm7xxD99JzYjg+9L/++wPjnzj zXL/9+Qt+z75z9k7gq8XOvS5zO6+Vb5e1iFIP6lI89eiq0osxRmJhlrMRcWJADb1Pfc3BAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprAIsWRmVeSWpSXmKPExsWy7bCSvC7zjZ9xBqv6FS3W3D7EaPH/0WtW ix3bRSzONr1ht7i8aw6bxefeI4wWO+ecZLW43biCzWLBxkeMDpwe23ZvY/XYcXcJo8emVZ1s Hn1bVjF6bL82j9nj8ya5ALYoLpuU1JzMstQifbsEroztX66yFSzTr5jX+ou9gfGXahcjB4eE gIlEw1+mLkYuDiGBHYwSpx8uY+ti5ASKS0pMu3iUGaJGWOLw4WKImreMEo8/PWAFqREWiJe4 0XIHzBYRiJI41HOHHaSIWWAKk8T9P7vZIDq2M0usebyZBaSKTUBLYv+LG2Ab+AUUJa7+eMwI YvMK2Elcv7SFCcRmEVCVWPFuJpgtKhAmsXPJYyaIGkGJkzOfsIBcxCngKPHnYzBImFlAXeLP vEvMELa4xK0n85kgbHmJ7W/nME9gFJ6FpHsWkpZZSFpmIWlZwMiyilEytaA4Nz232LDAKC+1 XK84Mbe4NC9dLzk/dxMjONK0tHYw7ln1Qe8QIxMH4yFGCQ5mJRHez9bf4oR4UxIrq1KL8uOL SnNSiw8xSnOwKInzfp21ME5IID2xJDU7NbUgtQgmy8TBKdXAdE5H0CJ27ZNpnMWBl+9MjXWa ut5twakjV36Knj3G7XPw4KR5/+ct2SV26lFS5fTZ7q9394n2lstqbHh+Ze3nf0Hzqh/+DFe2 fRSp6n376ny1pRnyNf6cBp+bls06XvOK54LU9LqWq+dtVBv23vylcEP7/C53V5mb0T63cjy2 3HMImyRYN+msRv6TAyvXcYq6NOje8WEPP7DF9p3ZdVmpNP51aQ2LL97ZnarbuCsz4nr34jdN C7eY3Jiw9d0Cfrf1BobqRRYNMuz/3239LLa2/f+WSRG9FYbhR7g2tYSfDApPeCd0vsLoo3vE +wtGc7M1U/o/aN5t3jGroHN24aya0jMP8pynaJ2Sl7HoY0k9HKPEUpyRaKjFXFScCADYtlxw IwMAAA== X-CMS-MailID: 20200629120107epcas1p3d599c93a005a36d3caba86785d27da27 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200622152844epcas1p2309f34247eb9653acdfd3818b7e6a569 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> <267623b3-9fc5-886e-3554-b86fa1e57ccb@collabora.com> Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hi Enric, On 6/29/20 8:26 PM, Enric Balletbo i Serra wrote: > 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. OK. Thanks for your reply. > > 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: >>>> >>>> >>>> >>> >>> >> >> > > -- Best Regards, Chanwoo Choi Samsung Electronics