It is written in the docs
The value of portSUPPRESS_TICKS_AND_SLEEP()'s single parameter equals the total number of tick periods before a task is due to be moved into the Ready state. The parameter value is therefore the time the microcontroller can safely remain in a deep sleep state, with the tick interrupt stopped (suppressed).
So, how is user able to control this parameter?
I’m working in IAR IDE with stm32l151 chip and using default implementation of portSUPPRESS_TICKS_AND_SLEEP. I set blinking of a led in Idle task (at every entrance turn on/off) and led blinking was pretty recognizable for a human eye. I’ve tried to always pass to portSUPPRESS_TICKS_AND_SLEEP 2000, 200, 20, 2 ticks (in my project 1 tick = 1 ms) from prvGetExpectedIdleTime but after that led stays active all the way.
Sorry for the noob question but in the docs it’s just far from obvious.