Re: [PATCH] ARM: tegra: Populate OPP table for Tegra20 Ventana

[Jon Hunter]

On 11/11/2020 13:47, Dmitry Osipenko wrote:
> 11.11.2020 13:38, Jon Hunter пишет:
>> Commit 9ce274630495 ("cpufreq: tegra20: Use generic cpufreq-dt driver
>> (Tegra30 supported now)") update the Tegra20 CPUFREQ driver to use the
>> generic CPUFREQ device-tree driver. Since this change CPUFREQ support
>> on the Tegra20 Ventana platform has been broken because the necessary
>> device-tree nodes with the operating point information are not populated
>> for this platform. Fix this by updating device-tree for Venata to
>> include the operating point informration for Tegra20.
>>
>> Fixes: 9ce274630495 ("cpufreq: tegra20: Use generic cpufreq-dt driver (Tegra30 supported now)")
>> Cc: stable@xxxxxxxxxxxxxxx
>>
>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
>> ---
>>  arch/arm/boot/dts/tegra20-ventana.dts | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/tegra20-ventana.dts b/arch/arm/boot/dts/tegra20-ventana.dts
>> index b158771ac0b7..055334ae3d28 100644
>> --- a/arch/arm/boot/dts/tegra20-ventana.dts
>> +++ b/arch/arm/boot/dts/tegra20-ventana.dts
>> @@ -3,6 +3,7 @@
>>  
>>  #include <dt-bindings/input/input.h>
>>  #include "tegra20.dtsi"
>> +#include "tegra20-cpu-opp.dtsi"
>>  
>>  / {
>>  	model = "NVIDIA Tegra20 Ventana evaluation board";
>> @@ -592,6 +593,16 @@ clk32k_in: clock@0 {
>>  		#clock-cells = <0>;
>>  	};
>>  
>> +	cpus {
>> +		cpu0: cpu@0 {
>> +			operating-points-v2 = <&cpu0_opp_table>;
>> +		};
>> +
>> +		cpu@1 {
>> +			operating-points-v2 = <&cpu0_opp_table>;
>> +		};
>> +	};
>> +
>>  	gpio-keys {
>>  		compatible = "gpio-keys";
>>  
>>
> 
> This could be wrong to do because CPU voltage is fixed to 1000mV in
> Ventana's DT, are you sure that higher clock rates don't require higher
> voltages? What is the CPU process ID and SoC speedo ID on Ventana?

I see this in the bootlog ...

[    2.797684] tegra20-cpufreq tegra20-cpufreq: hardware version 0x2 0x2

> You could easily hook up CPU voltage scaling, please see acer-500 DT and
> patch [1] for examples of how to set up regulators in DT. But then it
> shouldn't be a stable patch.

According to the Ventana design guide the CPU voltage range is 0.8-1.0V
and so it appears to be set to the max. The CPUFREQ test is reporting
the following ...

cpu: cpufreq: - CPU#0:
cpu: cpufreq:   - supported governors:
cpu: cpufreq:     - ondemand *
cpu: cpufreq:     - performance
cpu: cpufreq:     - schedutil
cpu: cpufreq:   - supported rates:
cpu: cpufreq:     -  216000
cpu: cpufreq:     -  312000
cpu: cpufreq:     -  456000
cpu: cpufreq:     -  608000
cpu: cpufreq:     -  760000
cpu: cpufreq:     -  816000
cpu: cpufreq:     -  912000
cpu: cpufreq:     - 1000000 *
cpu: cpufreq: - CPU#1:
cpu: cpufreq:   - supported governors:
cpu: cpufreq:     - ondemand *
cpu: cpufreq:     - performance
cpu: cpufreq:     - schedutil
cpu: cpufreq:   - supported rates:
cpu: cpufreq:     -  216000
cpu: cpufreq:     -  312000
cpu: cpufreq:     -  456000
cpu: cpufreq:     -  608000
cpu: cpufreq:     -  760000
cpu: cpufreq:     -  816000
cpu: cpufreq:     -  912000
cpu: cpufreq:     - 1000000 *

Cheers
Jon

-- 
nvpublic