Re: [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent

From: Marc Zyngier <maz@kernel.org>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: "Enric Balletbo i Serra" <enric.balletbo@collabora.com>,
	"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
Subject: Re: [PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent
Date: Mon, 29 Jun 2020 14:22:29 +0100	[thread overview]
Message-ID: <636bcc73fa658747626e36d71bfcc4f9@kernel.org> (raw)
In-Reply-To: <154fe5b6-6a05-c2b7-3014-2f7b9c2049f9@samsung.com>

On 2020-06-29 12:29, 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.

It is way too late. Firmware exists (mainline u-boot, for one) that
do not expose the new property, and you can't demand that people
upgrade. This is an ABI bug, and we now have to live with it.

So, yes to fixing the DT, and no to *only* fixing the DT.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...