linux-kernel - Re: [PATCH 2/2] arm64: dts: rockchip: Define values for the IPA governor for rock960

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Message-ID: <945577ba-d57a-cdbc-27a3-755e13dade37@linaro.org>
Date:   Sun, 9 Jun 2019 00:05:15 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Heiko Stübner <heiko@...ech.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/Rockchip SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC support" 
        <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH 2/2] arm64: dts: rockchip: Define values for the IPA
 governor for rock960

On 08/06/2019 00:18, Linus Walleij wrote:
> On Tue, Jun 4, 2019 at 6:58 PM Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
> 
>> The intelligent power allocator PID coefficient to be set in sysfs
>> are:
>>
>>     k_d: 0
>>     k_po: 79
>>     k_i: 10
>>     k_pu: 50
> 
> With all the other interesting parametrization in the device tree
> I kind of wonder why the PID regulator constants defaults are
> not set up from device tree?
> 
> Any specific reason?

None I'm aware of. I guess these constants are considered as tweak
values and not hardware related.

> To me it seems like the kind of stuff userpace will invariably just
> get wrong or forget about (somebody just runs a different
> distribution without the extra magic to set sysfs right) unless
> we supply good defaults.

I agree.

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