From: Enric Balletbo i Serra <enric.balletbo@collabora.com>
To: Chanwoo Choi <cw00.choi@samsung.com>, Marc Zyngier <maz@kernel.org>
Cc: "Heiko Stübner" <heiko@sntech.de>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
kernel-team@android.com,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent
Date: Mon, 29 Jun 2020 13:05:28 +0200 [thread overview]
Message-ID: <3de68490-d788-e416-dd5f-d4d6e7eca61a@collabora.com> (raw)
In-Reply-To: <c1a5b730-0554-bb90-9d8d-b50390482e96@samsung.com>
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@samsung.com> 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 <maz@kernel.org>
>>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>>
>>
>> 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:
>
>
>
next prev parent reply other threads:[~2020-06-29 19:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200622152844epcas1p2309f34247eb9653acdfd3818b7e6a569@epcas1p2.samsung.com>
[not found] ` <20200622152824.1054946-1-maz@kernel.org>
2020-06-29 2:43 ` [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent Chanwoo Choi
2020-06-29 8:18 ` Marc Zyngier
2020-06-29 11:09 ` Chanwoo Choi
2020-06-29 11:05 ` Enric Balletbo i Serra [this message]
2020-06-29 11:29 ` Chanwoo Choi
2020-06-29 11:26 ` Enric Balletbo i Serra
2020-06-29 12:12 ` Chanwoo Choi
2020-06-29 13:22 ` Marc Zyngier
2020-06-30 0:49 ` Chanwoo Choi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3de68490-d788-e416-dd5f-d4d6e7eca61a@collabora.com \
--to=enric.balletbo@collabora.com \
--cc=cw00.choi@samsung.com \
--cc=heiko@sntech.de \
--cc=kernel-team@android.com \
--cc=kyungmin.park@samsung.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=maz@kernel.org \
--cc=myungjoo.ham@samsung.com \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).