AM5728: How to set my cpu to maximum speed

Swapna yendrapalli

Intellectual 625 points

Part Number: AM5728

Hello,

1) We are using SDK TI-SDK-4.0.0.4-kernel-4.9.28 and want to set the CPU frequency to 1.5GHz without frequency scaling.

Could you please let us know the step by step procedure to do this?

2) We want to look at the current cpu frequency and understand there are many ways to this.

- sysfs is not an option as we don't have freq scaling enabled and I only see

root@CPS:/sys/devices/system/cpu/cpu0# ls
of_node power subsystem topology uevent

- cat /proc/cpuinfo shows

root@CPS:/sys/devices/system/cpu/cpufreq# cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 12.29
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x2
CPU part        : 0xc0f
CPU revision    : 2

I don't see the CPU frequency but there is a BogoMips field which seemed to be a low value(12.29). Is this correct?

Thanks,

Swapna

over 7 years ago

0 Pavel Botev over 7 years ago

TI__Guru**** 170625 points

Swapna,

1. You can also change MPU A15 frequency from u-boot or kernel, check below pointers for more info:

software-dl.ti.com/.../How_to_Guides_Linux_Porting_Guide_AM571x_AM570x_Speed_Grades.html

software-dl.ti.com/.../Foundational_Components_Kernel_Drivers.html

processors.wiki.ti.com/.../Processor_SDK_Linux_Automotive_FAQ

2. You can use omapconf or dump A15 PLL registers and calculate the clock based on the values

Regards,
Pavel

0 Swapna yendrapalli over 7 years ago in reply to Pavel Botev

Intellectual 625 points

Thanks Pavel !!. I can see our CPU is set to Maximum Speed.

- You can use omapconf or dump A15 PLL registers and calculate the clock based on the values
Could you send us an example to show how to calculate the clock based on PLL registers?

On the same note omapconf tool is helpful. Is there a command to retrieve QSPI/SPI/I2C speeds using this tool?

0 Swapna yendrapalli over 7 years ago in reply to Swapna yendrapalli

Intellectual 625 points

Forgot to ask why is BogoMIPS value is so low ( 12.29 ) on A15 processor.
On a A9 processor BogoMIPS : 1993.93

0 Pavel Botev over 7 years ago in reply to Swapna yendrapalli

TI__Guru**** 170625 points

Swapna yendrapalli said:
Could you send us an example to show how to calculate the clock based on PLL registers?

You can use GEL file or u-boot code base to check how MPU PLL registers are used to setup the frequency

Swapna yendrapalli said:
Is there a command to retrieve QSPI/SPI/I2C speeds using this tool?

No, I can not find such command. You can use omapconf to dump PRCM/PLL registers, thus to calculate the clock frequency supplied to QSPI/SPI/I2C modules. You can also check if the clock framework can be in help:

Regards,
Pavel

0 Pavel Botev over 7 years ago in reply to Swapna yendrapalli

TI__Guru**** 170625 points

Swapna yendrapalli said:
Forgot to ask why is BogoMIPS value is so low ( 12.29 ) on A15 processor.
On a A9 processor BogoMIPS : 1993.93

Check below pointers regarding BogoMIPS:

Regards,
Pavel

0 Swapna yendrapalli over 7 years ago in reply to Pavel Botev

Intellectual 625 points

Thanks. Could you please advise what is the correct BogoMips value for AM5728?

0 Pavel Botev over 7 years ago in reply to Swapna yendrapalli

TI__Guru**** 170625 points

Swapna,

Yes, your BogoMIPS value seems to be correct. I have the same on my side, where I use AM572x EVM with A15 at 1GHz:

root@am57xx-evm:~# cat /proc/cpuinfo
processor   : 0
model name   : ARMv7 Processor rev 2 (v7l)
BogoMIPS   : 12.29
Features   : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer   : 0x41
CPU architecture: 7
CPU variant   : 0x2
CPU part   : 0xc0f
CPU revision   : 2

processor   : 1
model name   : ARMv7 Processor rev 2 (v7l)
BogoMIPS   : 12.29
Features   : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer   : 0x41
CPU architecture: 7
CPU variant   : 0x2
CPU part   : 0xc0f
CPU revision   : 2

Hardware   : Generic DRA74X (Flattened Device Tree)
Revision   : 0000
Serial       : 0c01600e65220121

Seems that for Cortex-A15 ARM processor, BogoMIPS can not be used to calculate to speed/frequency. And this seems to be generic ARM/Linux question, not TI specific. You might get more details from ARM or generic Linux forums. See for example the below pointer:

https://forum.odroid.com/viewtopic.php?f=95&t=15642

You can check Cortex-A15 ARM processor speed/frequency from user space with omapconf tool:

root@am57xx-evm:~# omapconf --cpuinfo

root@am57xx-evm:~# omapconf dump dpll mpu

root@am57xx-evm:~# omapconf show dpll

root@am57xx-evm:~# omapconf show opp

Regards,
Pave

0 Swapna yendrapalli over 7 years ago in reply to Pavel Botev

Intellectual 625 points

Thanks!!

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AM5728: How to set my cpu to maximum speed