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Mon, 29 Jun 2020 20:18:24 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20200629111824epsmtip1d9f39c9a50b08335436aa1db858cdacc~c-7E4Xod-0337403374epsmtip1l; Mon, 29 Jun 2020 11:18:24 +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: <154fe5b6-6a05-c2b7-3014-2f7b9c2049f9@samsung.com> Date: Mon, 29 Jun 2020 20:29:36 +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: <3de68490-d788-e416-dd5f-d4d6e7eca61a@collabora.com> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrOJsWRmVeSWpSXmKPExsWy7bCmri7juZ9xBhtnmlmsuX2I0eL/o9es Fju2i1icbXrDbnF51xw2i8+9Rxgtds45yWpxu3EFm8WCjY8YHTg9tu3exuqx4+4SRo9NqzrZ PPq2rGL02H5tHrPH501yAWxR2TYZqYkpqUUKqXnJ+SmZeem2St7B8c7xpmYGhrqGlhbmSgp5 ibmptkouPgG6bpk5QEcpKZQl5pQChQISi4uV9O1sivJLS1IVMvKLS2yVUgtScgosC/SKE3OL S/PS9ZLzc60MDQyMTIEKE7Izpn3vYStYrFnROf86UwPjb4UuRk4OCQETic//1zJ1MXJxCAns YJS4vvofI4TziVHi0ruJ7BDON0aJ/aca2WFall1pYYNI7GWUmN7WwgLhvGeU+N/xkxGkSlgg XuJGyx1WEFtEIEqi/+M3sCXMApOYJCYt+wCWYBPQktj/4gYbiM0voChx9cdjsGZeATuJRdNv sIDYLAKqEk9vngSzRQXCJE5ua4GqEZQ4OfMJWJxTwFGie9N9JhCbWUBc4taT+VC2vMT2t3OY QRZLCKzlkHhw6yGQwwHkuEj09flAvCMs8er4FqjXpCQ+v9vLBmFXS6w8eYQNoreDUWLL/gus EAljif1LJzOBzGEW0JRYv0sfIqwosfP3XEaIvXwS7772sEKs4pXoaBOCKFGWuPzgLhOELSmx uL2TbQKj0iwk38xC8sEsJB/MQli2gJFlFaNYakFxbnpqsWGBMXJ0b2IEp1gt8x2M095+0DvE yMTBeIhRgoNZSYT3s/W3OCHelMTKqtSi/Pii0pzU4kOMpsDwncgsJZqcD0zyeSXxhqZGxsbG FiaGZqaGhkrivL5WF+KEBNITS1KzU1MLUotg+pg4OKUamIq1jA68+TfTcXkT2wvb5dobPD7f nn3+S8eHrKrytV1LGd7tfDP3aXrv4pglM9M8xX73aJxgYnF49kB9yhVljr18rN5rzxvOKRVg FJ6qXXn20cHXW0+zq962cVG7pnawT/yBhBGT0aOrgYaBTr+XW/PZ667UOPre0MR7Z09WEHOt YVMrF2eH+NOCb8f+qubmHlY55l/sdLJW8au/CePe48sk+upc32uGSxdq7ftYMFUn0nKG+o04 ZiHLD7wLr5U8PHfNzorjdPu/zMOyz2IianexHlukFH16j3lvY9qhm0V96ZtfyIc9XuH78mC9 UD4jSwO7hsMdPR33u4c+7ua/d1j1pfTGSX/mhN+Yx1rXr8RSnJFoqMVcVJwIAOdSvLw6BAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprEIsWRmVeSWpSXmKPExsWy7bCSnC7DuZ9xBnM7rCzW3D7EaPH/0WtW ix3bRSzONr1ht7i8aw6bxefeI4wWO+ecZLW43biCzWLBxkeMDpwe23ZvY/XYcXcJo8emVZ1s Hn1bVjF6bL82j9nj8ya5ALYoLpuU1JzMstQifbsEroxp33vYChZrVnTOv87UwPhboYuRk0NC wERi2ZUWti5GLg4hgd2MEncuXWGGSEhKTLt4FMjmALKFJQ4fLoaoecsoceLPKrAaYYF4iRst d1hBbBGBKIlDPXfYQYqYBaYwSdz/sxtq6mkmifN377CAVLEJaEnsf3GDDcTmF1CUuPrjMSOI zStgJ7Fo+g2wGhYBVYmnN0+C2aICYRI7lzxmgqgRlDg58wlYnFPAUaJ7032wOLOAusSfeZeY IWxxiVtP5kPF5SW2v53DPIFReBaS9llIWmYhaZmFpGUBI8sqRsnUguLc9NxiwwLDvNRyveLE 3OLSvHS95PzcTYzgaNPS3MG4fdUHvUOMTByMhxglOJiVRHg/W3+LE+JNSaysSi3Kjy8qzUkt PsQozcGiJM57o3BhnJBAemJJanZqakFqEUyWiYNTqoHpCKfGs+8H3q8RV/mgk5oo4iXWsV2R MUn/zhOj16IvPogFrYrZOWuZ+J6L/RFCz+rN2vU+mvVmbe68s2P90aX3Ll1p8nHebDZn81T3 hwoX3k2ZNLO1d/KHlsKs8vA4PsZTEqHcDj5ejJesX213V9o9bcbqpl3LnQ0rdLUY1qnfD/7/ cdlh9t8hvyZuur3sm5O+9s8Lf369uyQfH+mQrnjscGCVs+lKV0VjuameP2Zp3jabJ/l2f5lc SorIy/e+ZW+5bHcyf9C6cNd84ZVEfesJE4/4CQuGprQ9s2nNW1hqpnK+ReVpLJ8Hy5FLnOoz vt914LMWUf18/gxTfu8D7X39roa/nXYuNF4uJnymyGuaEktxRqKhFnNRcSIAdNbXgyUDAAA= X-CMS-MailID: 20200629111825epcas1p16a9284e083090d9d7e104cf40b562226 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> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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/ > > 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