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 <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://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: > > >
