linux-kernel - Re: [RFC/RFT v3 14/14] arm64: dts: meson-g12b-odroid-n2: enable DVFS

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Date:   Wed, 3 Jul 2019 13:54:57 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     jbrunet@...libre.com, khilman@...libre.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [RFC/RFT v3 14/14] arm64: dts: meson-g12b-odroid-n2: enable DVFS

On 03/07/2019 01:45, Martin Blumenstingl wrote:
> On Mon, Jul 1, 2019 at 11:13 AM Neil Armstrong <narmstrong@...libre.com> wrote:
>>
>> Enable DVFS for the Odroid-N2 by setting the clock, OPP and supply
>> for each cores of each CPU clusters.
>>
>> The first cluster uses the "VDDCPU_B" power supply, and the second
>> cluster uses the "VDDCPU_A" power supply.
>>
>> Each power supply can achieve 0.73V to 1.01V using 2 distinct PWM
>> outputs clocked at 800KHz with an inverse duty-cycle.
>>
>> DVFS has been tested by running the arm64 cpuburn at [1] and cycling
>> between all the possible cpufreq translations of each cluster and
>> checking the final frequency using the clock-measurer, script at [2].
>>
>> [1] https://github.com/ssvb/cpuburn-arm/blob/master/cpuburn-a53.S
>> [2] https://gist.github.com/superna9999/d4de964dbc0f84b7d527e1df2ddea25f
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> 
> [...]
>> +       vddcpu_b: regulator-vddcpu-b {
>> +               /*
>> +                * Silergy SY8120B1ABC Regulator.
>> +                */
> interesting that they use different regulator ICs for CPU A and CPU B
> the public schematics confirm your comments
> 

Yep they use a Silergy one for VDDCPU_B on every schematics I have.

The A311D VIM3 have a slightly different one, but still Silergy for VDDCPU_B.
https://dl.khadas.com/Hardware/VIM3/Schematic/VIM3_V11_Sch.pdf

Neil