AM5728: 500Mhz MPU can work?

Sung-IL

Part Number: AM5728

Dear Champs,

Is it possible to run MPU at 500Mhz in AM5728?

My customer tried to set lower clock set in A15 and DSP when thermal issue was occurred.

But, when my customer tried to set A15 at 500Mhz by referring below, they could not find any difference in the performance with 800Mhz and want to get details how they can set it.

https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/linux/How_to_Guides_Linux_Porting_Guide_AM571x_AM570x_Speed_Grades.html

And also, is it possible to re-set CPU clock of A15 and DSP at runtime when thermal issue was occurred?

And in the kernel setting, they found 'CPU Power Management > CPU Freq governor' menu and they want to know details how it works. Could you please help to resolve these 3 questions?

Thanks and Best Regards,

SI.

over 4 years ago

0 Keerthy J over 4 years ago

TI__Guru**** 162770 points

Hi SI,

If you are using the 6.03 SDK there is already thermal framework in place that should reduce the frequency upon detecting high temperatures.

How are you reducing the frequency to 800MHz? Are you changing the OPP table in device tree?

Sung-IL said:
And also, is it possible to re-set CPU clock of A15 and DSP at runtime when thermal issue was occurred?

A15 is possible but DSP is fixed.

Also data sheet:www.ti.com/.../am5728.pdf

So 500MHz is not supported for AM5728.

- Keerthy

0 Sung-IL over 4 years ago in reply to Keerthy J

TI__Mastermind 30850 points

Hi Keerthy,

Thanks for your response. this is good point.

Is there any document for thermal framework in linux except below?

https://processors.wiki.ti.com/index.php/GLSDK_Thermal_framework

it seemed there were only OPP_NORM, OPP_OD operate when I checked below.

Is there any way to use max frequency of 1.5Ghz in AM5728?

When my customer set scaling_governor to 'performance', they found it runs at 1.5Ghz as below.

Can they use this for their high-performance processing?

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

performance

cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq

1500000

The max freq in each OPP described in datasheet is 'MAXIMUM', right?

is it OK to use 500Mhz in AM5728 MPU to reduce heat dissipation when thermal issue will be occurred?

I found there was only change between OPP_NORM and OPP_OD in our thermal framework document.

But, they can set it to 500Mhz as below.

Can they use below mode to reduce heat dissipation efficiently?

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

powersave

cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq

500000

Thanks and Best Regards,

SI.

+1 Keerthy J over 4 years ago in reply to Sung-IL

TI__Guru**** 162770 points

Hi SI,

500MHz is not mentioned is the Data sheet for AM578. So you could try but
the device will not be characterized for that frequency.

Also for 1.5GHz. This is the below definition for am5728:

        cpu0_opp_table: opp-table {
                compatible = "operating-points-v2-ti-cpu";
                syscon = <&scm_wkup>;

                opp_nom-1000000000 {
                        opp-hz = /bits/ 64 <1000000000>;
                        opp-microvolt = <1060000 850000 1150000>,
                                        <1060000 850000 1150000>;
                        opp-supported-hw = <0xFF 0x01>;
                        opp-suspend;
                };

                opp_od-1176000000 {
                        opp-hz = /bits/ 64 <1176000000>;
                        opp-microvolt = <1160000 885000 1160000>,
                                        <1160000 885000 1160000>;

                        opp-supported-hw = <0xFF 0x02>;
                };

                opp_high@1500000000 {
                        opp-hz = /bits/ 64 <1500000000>;
                        opp-microvolt = <1210000 950000 1250000>,
                                        <1210000 950000 1250000>;
                        opp-supported-hw = <0xFF 0x04>;
                };
        };

So 1.5GHz is supported already.

Sung-IL said:
When my customer set scaling_governor to 'performance', they found it runs at 1.5Ghz as below.

Can they use this for their high-performance processing?

The documentation is not updated but we do support 1.5GHz already as shown above.

If no further questions please click on verify answer.

Best Regards,
Keerthy

0 Sung-IL over 4 years ago in reply to Keerthy J

TI__Mastermind 30850 points

Keerthy,

Thanks for the clarification.

Is there any document for thermal framework in linux except below?

https://processors.wiki.ti.com/index.php/GLSDK_Thermal_framework

Thanks and Best Regards,

SI.

+1 Keerthy J over 4 years ago in reply to Sung-IL

TI__Guru**** 162770 points

Hi SI,

Apart from that there is general Linux thermal documentation here: Documentation/driver-api/thermal/sysfs-api.rst

If no other questions please click on verify answer.

Best Regards,
Keerthy

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AM5728: 500Mhz MPU can work?