usb_pump thread does not restore after chSysDisable/Enable

[tsichevski]

Hi all,

I use ChibiOS_17.6.3
I use power STOP mode to save power on my battery-powered device.
I shut my system down and restart it according to the recommendations here: http://www.chibios.org/dokuwiki/doku.ph ... s:kb:power
Everything goes well, but I noticed that the thread named "usb_pump" does not reappear after system has restarted.

The driver sources say that this thread can only be started once:

Code: Select all

#if defined(_CHIBIOS_RT_)
    /* Creates the data pump thread. Note, it is created only once.*/
    if (usbp->tr == NULL) {
      thread_descriptor_t usbpump_descriptor = {
        "usb_pump",
        THD_WORKING_AREA_BASE(usbp->wa_pump),
        THD_WORKING_AREA_END(usbp->wa_pump),
        STM32_USB_OTG_THREAD_PRIO,
        usb_lld_pump,
        (void *)usbp
      };

      usbp->tr = chThdCreateI(&usbpump_descriptor);
      chSchRescheduleS();
  }
#endif


The sources also say "This function must be executed by a system thread in order to make the USB driver work."

My question is: how can I restart this thread after returning from STOP mode?

Regards,
Vladimir

PS: I notices this system thread disappeared in ChibiOS 18.2.1 code.

[Giovanni]

Hi,

It depends on what you do before entering STOP and after leaving it. Try stopping/starting the USB driver.

Anyway, it would be better to migrate to 18.x.

Giovanni

[tsichevski]

> Try stopping/starting the USB driver.
I do this. This does not affect the usb_pump thread. There is no means to stop it nicely either.
As a workaround, I zero the USBD1.tr field after the RT is stopped by chSysDisable().

Regards,
Vladimir

[Giovanni]

The thread does not stop by itself, do you restart the OS using chSysInit()?

Giovanni

[tsichevski]

Yes, my main() looks like this:

Code: Select all

  for(;;) {
    chSysInit();
    ...initialize app threads and periphery
    chThdWait(... the main control loop thread);
    ...stop app threads and shutdown periphery
   
    chSysDisable();
    // stop the system timer
    STM32_ST_TIM->CR1 &= ~(TIM_CR1_CEN);
    nvicDisableVector(STM32_TIM2_NUMBER);
    chSysEnable();

    ...go power stop mode

    chSysDisable();
  }


[Giovanni]

If RAM content is preserved then you should not re-initialize the RTOS, just enable the systick timer again, Probably you could also not terminate other threads.

Giovanni

[tsichevski]

Thanks, Giovanni, I will give it a try.