qapi_Timer_Sleep() does not work with other units than TICK

[ziron4]

First of all, thank you for your amazing work!

The issue:
When I try to use the qapi_Timer_Sleep function from the qapi_timer.h, the module never comes back if I use other time units than QAPI_TIMER_UNIT_TICK.

Here is my code (That does not work unless I use the QAPI_TIMER_UNIT_TICK):

#include "qapi.h"
#include "qapi_timer.h"
#include "app_uart.h"

int dam_app_start(void)
{
  uart_dbg_init(); /* Uart setup. */
  
  qapi_Timer_Sleep(1, QAPI_TIMER_UNIT_USEC, true);
  UART_DBG("Module running\n\r");
  return 0;
}

[Thalhammer]

I did encounter this problem as well and will look into it, once I'm back home.
Did you try to set deferrable (the last one) to false?
If it is a limitation of the API, one could only try to emulate it using a timer and semaphore, but this might not work for delays so short.

PS: There is now a debug/trace header in utils that allows for printf like traces but prepends the module (and one i figured it out the time).
EDIT: Note that this repo is very much in progress and nowhere near being done yet, so take all information/code with a grain of salt. Also feel free to add new examples and fix bugs you find. PR's are always welcome.

[Thalhammer]

Do you use GCC or ARM ?

[ziron4]

Will try to change the last argument to false.
I have used the qapi_Timer_Sleep function before with no problems

I use GCC

[ziron4]

How did you reverse engineer the .lib files?

[Thalhammer]

I used Cutter which is a gui for radare2.
You unpack the lib using arm-ar into individual object files and then you can open them right in Cutter.
Maybe I got something wrong there.
What I found out so far:
Sleep with UNIT_TICK works, but returns immediately even if you specify a long time.
Everything else seems to crash/never return.

EDIT: One thing to note is that unlike all other functions, the sleep api seems to swap parameter positions 1. gets second and 2. gets first. But I tried it the other way and it doesn't work either.

[Thalhammer]

It seems like UNIT_TICK is working, a tick is just extremly short.

TRACE("sleep\r\n");
int res = qapi_Timer_Sleep(20000000, QAPI_TIMER_UNIT_TICK, false);
TRACE("res=%d\r\n", res);

Resulted in a delay of about 1s between both prints. I tried smaller values and it seems to scale and be constant.
Calculating this back, a tick seems to be around 0,05 microseconds.
So if we don't get the other units to work we could at least integrate a workaround into qapi_Timer_Sleep that sleeps the requested time using ticks.

EDIT: if the last param is true it does not return.

[ziron4]

It could be a solution, but it gives a max delay of 3.58 min, which is not that long.
I will try to use the qapi_Timer_set and qapi_Timer_stop functions to get a bigger delay.

Sleep with UNIT_USEC seems to run over and return, I know because I waited for over an hour and it returned. uint32_t max = 4294967295 and with 1000000 usec every sec gives a overrun time of 71.6min.

[Thalhammer]

It could be a solution, but it gives a max delay of 3.58 min, which is not that long.

If the delay would be larger than say 2 minutes one could just divide by 2 minutes and way multiple times.
The overhead of looping and multiple calls won't be measurable at those delays.

[Thalhammer]

Note that the 19200081 is a guess based on output, but I think it is good enough since you won't be able to do really accurate timing anyway.

[ziron4]

I agree, it should be good enough.
EDIT: It's not realtime anyway