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 <cw00.choi@xxxxxxxxxxx> 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@xxxxxxxxxxxxxxx' 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 <maz@xxxxxxxxxx> >>>>> Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> >>>> >>>> >>>> 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: >>> >>> >>> >> >> > >
