linux-kernel - Re: [RFC-next 0/1] Odroid C2: Enable DVFS for cpu

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Date:   Tue, 10 Dec 2019 09:43:28 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Kevin Hilman <khilman@...libre.com>,
        Anand Moon <linux.amoon@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Jerome Brunet <jbrunet@...libre.com>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC-next 0/1] Odroid C2: Enable DVFS for cpu

On 09/12/2019 23:12, Kevin Hilman wrote:
> Anand Moon <linux.amoon@...il.com> writes:
> 
>> Some how this patch got lost, so resend this again.
>>
>> [0] https://patchwork.kernel.org/patch/11136545/
>>
>> This patch enable DVFS on GXBB Odroid C2.
>>
>> DVFS has been tested by running the arm64 cpuburn
>> [1] https://github.com/ssvb/cpuburn-arm/blob/master/cpuburn-a53.S
>> PM-QA testing
>> [2] https://git.linaro.org/power/pm-qa.git [cpufreq testcase]
>>
>> Tested on latest U-Boot 2019.07-1 (Aug 01 2019 - 23:58:01 +0000) Arch Linux ARM
> 
> Have you tested with the Harkernel u-boot?
> 
> Last I remember, enabling CPUfreq will cause system hangs with the
> Hardkernel u-boot because of improperly enabled frequencies, so I'm not
> terribly inclined to merge this patch.

Same, since the bootloader boots with the max supported freq of the board,
there is not real need of DVFS except for specific low-power use-cases.

And still, some early boards still use the bad SCPI freq table, we can't break them.

Neil

> 
>> Patch based on my next-20191031 for 5.5.x kernel.
>> Hope this is not late entry.
> 
> Re: "too late".  FYI... when you post things as RFC, it means you're
> looking for comments (Request For Comment) but that it's not intended
> for merging.
> 
> I didn't see any comments on this, but I also didn't see a non-RFC
> follow-up, so I didn't queue it for v5.5.
> 
> Kevin
>