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

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Date:   Mon, 24 Jun 2019 10:22:57 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     jbrunet@...libre.com, khilman@...libre.com
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, martin.blumenstingl@...glemail.com
Subject: Re: [RFC/RFT 14/14] arm64: dts: meson-g12b-odroid-n2: enable DVFS

On 20/06/2019 17:00, Neil Armstrong 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>
> ---
>  .../boot/dts/amlogic/meson-g12b-odroid-n2.dts | 96 +++++++++++++++++++
>  1 file changed, 96 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> index c3e0735e6d9f..0db1547bfb5a 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> @@ -114,6 +114,44 @@

[...]

I just ran a 4days long test, leading to ~4 729 015 transitions.

Here are the cpufreq trans_table content :

Cortex-A53:
   From  :    To
         :    100000    250000    500000    666666   1000000   1200000   1398000   1512000   1608000   1704000   1896000
   100000:         0     30975     20650     20649     20649     20649     20649     20649     20649     20649     20649
   250000:     20650         0     30975     20649     20649     20649     20649     20649     20649     20649     20649
   500000:     20650     20650         0     30973     20649     20648     20648     20648     20648     20648     20648
   666666:     20649     20649     20649         0     30972     20648     20648     20648     20648     20648     20648
  1000000:     20649     20649     20649     20648         0     30972     20648     20648     20648     20648     20648
  1200000:     20649     20649     20648     20648     20648         0     30972     20648     20648     20648     20648
  1398000:     20649     20649     20648     20648     20648     20648         0     30972     20648     20648     20648
  1512000:     20649     20649     20648     20648     20648     20648     20648         0     30972     20648     20648
  1608000:     20649     20649     20648     20648     20648     20648     20648     20648         0     30972     20648
  1704000:     20649     20649     20648     20648     20648     20648     20648     20648     20648         0     30972
  1896000:     30973     20649     20648     20648     20648     20648     20648     20648     20648     20648         0

Cortex-A73:
   From  :    To
         :    100000    250000    500000    666666   1000000   1200000   1398000   1512000   1704000
   100000:         0     45964     30643     30643     30643     30642     30642     30642     30642
   250000:     30643         0     45963     30642     30642     30642     30642     30642     30642
   500000:     30643     30642         0     45963     30642     30642     30642     30642     30642
   666666:     30643     30642     30642         0     45963     30642     30642     30642     30642
  1000000:     30643     30642     30642     30642         0     45963     30642     30642     30642
  1200000:     30642     30642     30642     30642     30642         0     45963     30642     30642
  1398000:     30642     30642     30642     30642     30642     30642         0     45963     30642
  1512000:     30642     30642     30642     30642     30642     30642     30642         0     45963
  1704000:     45963     30642     30642     30642     30642     30642     30642     30642         0

Neil