AM62L: Clarification on CPUFreq/DFS and OP-TEE Support in AM62LX SDK

Hello J S Ninad,

Ninad J S said:

1.Is CPUFreq/DFS actually supported on AM62LX in SDK 11.02.08.02,  Is this feature available in the latest SDK?

Yes, its in SDK 11.02. The documentation is still in progress but should be included in SDK 12.0. I've made a note to get the software buildsheet to be updated.

Ninad J S said:

2.Which document should be considered the correct reference for supported features — release notes or build sheet?

Both are updated per release so both can be used as a reference.

Ninad J S said:

3.In the latest release notes, it mentions “New 2-Stage A53 Boot Flow including OP-TEE.”
However, New 2-Stage A53 Boot Flow including OP-TEE support was already present in SDK 11.01.16.13.
Could you clarify what changes or enhancements were introduced in OP-TEE support between these SDK versions?

I'll need to check with the development team and will get back to you.

Best Regards,

Anshu

Hello Anshu 

Anshu Madwesh said:

Yes, its in SDK 11.02. The documentation is still in progress but should be included in SDK 12.0. I've made a note to get the software buildsheet to be updated.

As per my understanding from your replies . SDK 11.02.08.02 supports CPUFreq/DFS is that correct ? Or it will be supported  in SDK 12.0 ?

Anshu Madwesh said:

Both are updated per release so both can be used as a reference.

But in 11.02.08.02 build sheet ( https://software-dl.ti.com/processor-sdk-linux/esd/AM62LX/11_02_08_02/exports/docs/devices/AM62LX/linux/Release_Specific_Build_Sheet.html) its mentioned as CPUFreq/DFS not supported . 

Can you clarify regarding this .

Thanks and regards,

J S Ninad

Hello J S Ninad,

Yes its in SDK 11.02. I just booted up an EVM and confirmed it.

The documentation is still in progress and will be updated later.

Best Regards,

Anshu

Hello Anshu , 

What is the specific changes required to enable CPUFreq/DFS in 11.02.08.02
Is there any patch for the same . 

And also can u clarify regarding the OPTEE 

Regards ,
J S Ninad 

Hello J S Ninad,

CPUFreq is already added in SDK 11.02. If you want to back port it to another version, then you can use these patches:

https://patchew.org/linux/20260116-am62l-cpufreq-v2-0-eac7e2e78d29@ti.com/

The OPTEE change was just added again because of the silicon revision of the AM62L device.

Please do confirm you are working with AM62L revision 1.1, not 1.0.

Best Regards,

Anshu

Hello Anshu ,

Anshu Madwesh said:

CPUFreq is already added in SDK 11.02. If you want to back port it to another version, then you can use these patches:

I had added the patch in below 4 files as mentioned in the patch file   :

       modified: arch/arm64/boot/dts/ti/k3-am62l-wakeup.dtsi
  modified: arch/arm64/boot/dts/ti/k3-am62l3.dtsi
  modified: drivers/cpufreq/cpufreq-dt-platdev.c
  modified: drivers/cpufreq/ti-cpufreq.c

When Tested in our board i cant see cpufreq inside cpu0  and cpu 1 


When I gave dmesg | grep -i "CPU"

[    3.528568] cpu cpu0: _of_add_opp_table_v2: no supported OPPs
[    3.534418] cpu cpu0: OPP table can't be empty

These prints are observed, which are not there in the evk log as I referred here -gist.github.com/.../6dcceb80cf7bbd1e624ec210532538cb

Is there anything else to be implemented? By applying the patch, CPU freq could not be supported. Can I get any suggestions to debug .

Anshu Madwesh said:

Please do confirm you are working with AM62L revision 1.1, not 1.0.

We are working with AM62L Revision 1.1 

In optee we observed 1 failed testcase same was obsereved in evk board 
35382 subtests of which 1 failed
111 test cases of which 1 failed
0 test cases were skipped
TEE test application done!

regression_1041 FAILED first error at /usr/src/debug/optee-test/4.7.0+git/host/xtest/regression_1000.c:3413


Regards, 

J S Ninad

Hello J S Ninad,

Can you share a git diff of all the changes you made for CPUFreq?

For the OPTEE debug, please create a new post so the correct team member can provide support.

Best Regards,

Anshu

Hello Anshu ,

I did the changes as per latest SDK and it worked

Thank you for the support 

For further clarification can you share the commands that you used for testing in EVM board 

Anshu Madwesh said:

For the OPTEE debug, please create a new post so the correct team member can provide suppor

Sure i will .

Thanks and regards, 

J S Ninad

Hello J S Ninad,

You can follow the AM62x documentation for the commands to use. Just note the numbers might be different due to the maximum speeds of the device.

https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/latest/exports/docs/linux/Foundational_Components/Power_Management/pm_dfs.html

Best Regards,

Anshu

Hello Anshu ,

Thank you for the commands ,

We tested the cpu frequncy scaling and obsreved the power consumption changes accordinly when interfaces are in working .
But there is no major changes in power consumption when the board is just scaled down to less frequency without any working interfaces.

Can you share the power consumption details accordingly when CPU freq is changed in EVM.


Regards , 

J S Ninad

Hello J S Ninad,

The A53 cores are generally low power consumption so changing the frequency doesn't reduce the power consumption that much. You can see in the AM62L power consumption summary: https://www.ti.com/lit/an/sdaa019/sdaa019.pdf

Best Regards,

Anshu

Hello Anshu ,

I have a few urgent questions regarding CPU frequency and DFS:

1) When CPU frequency (CPUFreq/DFS) changes, what happens internally on the board or in the driver? Specifically, which parameters are affected—for example, clock, current, or others?
2) How can we validate and confirm, at the hardware level, that the CPU frequency has been set correctly? Specifically, how can we verify that the values we set via software actually take effect in the hardware?

3) If the CPU core voltage (VDD_CORE ) is fixed, what parameters or system behaviors will change when the CPU frequency is adjusted? 

4) Is there any specific clock that we can probe for the particular scaling frequency adjustment?

 5)Additionally , need the clarification regarding the below images 

Since this query is urgent, I would appreciate your clarification at the earliest.

Regards, 

Ninad

Hello J S Ninad,

Ninad J S said:

1) When CPU frequency (CPUFreq/DFS) changes, what happens internally on the board or in the driver? Specifically, which parameters are affected—for example, clock, current, or others?

CPUFreq only changes the A53 core frequency so it changes the clock. It doesn't change any other parameters. You can review the driver that you modified to see how it works.

Ninad J S said:

2) How can we validate and confirm, at the hardware level, that the CPU frequency has been set correctly? Specifically, how can we verify that the values we set via software actually take effect in the hardware?

You can use /sys/kernel/debug/clk to see the clock speeds.

Ninad J S said:

3) If the CPU core voltage (VDD_CORE ) is fixed, what parameters or system behaviors will change when the CPU frequency is adjusted? 

Just the clock speed.

Ninad J S said:

4) Is there any specific clock that we can probe for the particular scaling frequency adjustment?

Review the clock tree tool: https://dev.ti.com/sysconfig/#/start

Go to the site, select clock tree tool and select am62l.

Ninad J S said:

 5)Additionally , need the clarification regarding the below images 

The device can operate a lower frequency, but it won't be supported by CPUFreq. Instead you'll need to do a register write. The clock tree tool will tell you which registers need to be modified and you can use devmem2 to interact with the register.

Best Regards,

Anshu

Hello Anshu ,

Anshu Madwesh said:

CPUFreq only changes the A53 core frequency so it changes the clock. It doesn't change any other parameters. You can review the driver that you modified to see how it works.

Is there any test logs available where you confirmed the clock changes when cpu freq is changed ?

Anshu Madwesh said:

You can use /sys/kernel/debug/clk to see the clock speeds.

cat /sys/kernel/debug/clk/clk_summary - Should we check for a53 clock speed ?

From hardware side
Is there any specific clock which we can probe for this particular frequency adjustment? 

 Regards ,
Ninad

Hello J S Ninad,

Ninad J S said:

Is there any test logs available where you confirmed the clock changes when cpu freq is changed ?

I'm out of office so I don't have access to an EVM at the moment. I'll check if theres any internal test logs.

Ninad J S said:

cat /sys/kernel/debug/clk/clk_summary - Should we check for a53 clock speed ?

Yes CPUFreq is changing the A53 core speeds.

Ninad J S said:

Is there any specific clock which we can probe for this particular frequency adjustment? 

Please refer to the clock tree tool that I linked previously.

Best Regards,

Anshu

You can refer to these test logs: https://gist.github.com/DhruvaG2000/63334d7a29a1dde4712382a4f3bfc959

Thanks,

Anshu