linux-kernel - Re: [PATCH v3 0/5] Refactor thermal pressure update to avoid code duplication

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Message-ID: <19ecab72-4a2f-1f4a-b999-d3967a4a1a76@arm.com>
Date:   Tue, 9 Nov 2021 16:22:12 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Steev Klimaszewski <steev@...i.org>
Cc:     Thara Gopinath <thara.gopinath@...aro.org>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, sudeep.holla@....com,
        will@...nel.org, catalin.marinas@....com, linux@...linux.org.uk,
        gregkh@...uxfoundation.org, rafael@...nel.org,
        viresh.kumar@...aro.org, amitk@...nel.org,
        daniel.lezcano@...aro.org, amit.kachhap@...il.com,
        bjorn.andersson@...aro.org, agross@...nel.org
Subject: Re: [PATCH v3 0/5] Refactor thermal pressure update to avoid code
 duplication



On 11/9/21 3:46 PM, Steev Klimaszewski wrote:
> 
> On 11/9/21 2:29 AM, Lukasz Luba wrote:
>> Hi Steev,
>>
>> That's interesting what you've done with Rockchip RK3399.
>> I would like to reproduce your experiment on my RockPI 4B v1.3.
>> Could you tell me how you to add this boost frequency that you have
>> mentioned in some previous emails?
>>
>> I want to have similar setup to yours and I'll check all the subsystems
>> involved in the decision making process for triggering this boost freq.
>>
>> Thank you for your support.
>>
>> Regards,
>> Lukasz
> 
> 
> Hi Lukasz,
> 
> It was actually something that Armbian had been doing as an overlay for 
> their setup, and I thought, why does it need to be an overlay, when we 
> could simply hide it behind turbo-mode so that if users want to 
> overclock, they simply echo 1 and if it's unstable or cooling/power 
> isn't enough, they can echo 0 or leave it off (boost defaults to off) - 
> so that being said:
> 
> I apply this patch 
> https://gitlab.com/kalilinux/build-scripts/kali-arm/-/blob/master/patches/pinebook-pro/pbp-5.14/rk3399-opp-overclock-2GHz-turbo-mode.patch 
> which adds the 1.5GHz for little cores and 2GHz for the big to the 
> rk3399 dtsi
> 
> To enable at boot time, I simply have "echo 1 > 
> /sys/devices/system/cpu/cpufreq/boost" in my /etc/rc.local  And to 
> disable, simply echo 0 in there (it defaults to 0 so it's off and most 
> users won't know it exists.)
> 
> I'm pretty sure this is "abusing" turbo-mode, but it works well enough...
> 
> Hope that helps,
> 

Yes, that help. Thank you for the info.
I'll play a bit with this boosting and try to figure out
the mechanisms.

For the $subject patch set, I'm going to send v4, since
it's not affecting the boost usage. The newly introduced
interface must handle these boost frequency values and not
simply ignore them with also printing a warning.
They are valid frequencies and we should just put 0 to
the thermal pressure in such cases.

Regards,
Lukasz