TDA4VM: GTC time counter register access issues

Yang Tianxiang

Part Number: TDA4VM

Dear Support,

so far we are using GTC timer counter(64bits) as our SOC global shared time stamp. We found an issue that we would get wrong data from that register, GTC_CNTCV_LO , GTC_CNTCV_HI very occasionally.

We wrote test code to calculate the period of task which is set to 10ms cycle in MCU1-0 with max/min/avg data recorded. Below is the test result.

The average data is fine(about 9341us), but the max value is 1202062us. Below is the test code sample：

#define TICKS_TO_US 200

GetSystemTimer_u64()

{

uint63 cur_t = 0;

cur_t = (*(volatile uint64_t*)(0x00a90008)) / TICKS_TO_US;

asm(" dsb");asm(" isb");

}

Task(APP_10ms)

{

Timer_Duration = GetSystemTimer_u64() - Timer_start;

Timer_start = GetSystemTimer_u64();

}

The graph above just shows the summary of Timer_Duration

Could you give us any hints that what could lead to that issue? Thanks a lot for support.

over 2 years ago

0 Yang Tianxiang over 2 years ago

Prodigy 100 points

Just notes that we are confirmed that the wrong data does not comes from our task schedule. so we just assume that root cause should come from the gtc register. Maybe we access to it very fast since every soc core will access it and in some cases they will get data from that register in the meantime

0 Brijesh Jadav over 2 years ago in reply to Yang Tianxiang

TI__Guru**** 491485 points

Hi Yang,

Is there anything else running in parallel? Lets says some other higher priority task coming and blocking this task for longer duration.. Is it possible?

Regards,

Brijesh

0 Yang Tianxiang over 2 years ago in reply to Brijesh Jadav

Prodigy 100 points

it is possible to be blocked by higher priority IRQ, but would not block so much time. If so our system will crash, some module will report error.

0 Yang Tianxiang over 2 years ago in reply to Yang Tianxiang

Prodigy 100 points

for example, the periodic of CAN msgs sent by MCU is correct

0 Brijesh Jadav over 2 years ago in reply to Yang Tianxiang

TI__Guru**** 491485 points

But lets say higher priority task may be running multiple times or something, is there a possibility? Can you for the time being disable higher priority task and see GTC value?

0 Yang Tianxiang over 2 years ago in reply to Brijesh Jadav

Prodigy 100 points

the CAN MSG periodic during the error scenario is fine, in which also we did the test code... they are in the same AUTOSAR Task So we assume it could be proved that we do not have schedule issue... Besides the error scenario happens each 10 or 15 minutes, which means the GTC timer is not overflow

0 Brijesh Jadav over 2 years ago in reply to Yang Tianxiang

TI__Guru**** 491485 points

Yes, GTC is 64bit timer, so even if running at 200MHz, it will not overflow in 10min..

Just to confirm that the delay could be due to CAN MSG, can you try disabling it and check it out?

0 Yang Tianxiang over 2 years ago in reply to Brijesh Jadav

Prodigy 100 points

Disabling High priority Task and CAN Msg does not help, we are confirmed with that... Did you or some other customers ever found similar issues?

0 Brijesh Jadav over 2 years ago in reply to Yang Tianxiang

TI__Guru**** 491485 points

No, have not seen this issue.

In your code, instead of dividing the GTC timer value, can you just take the different of current and previous time and then plot this difference?

Rgds,

Brijesh

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TDA4VM: GTC time counter register access issues