AC power state bounces after plugging/unplugging AC power #88

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1. baodrate commented on Sep 22, 2026

   

   baodrate

   on Sep 22, 2026

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   I'm not confident, but is the issue something like this?

   • charger_task() reads AC state in a loop, and reads the AC-state

   EmbeddedController/common/charge_state.c

   Lines 1566 to 1573 in 8cbd986

   	while (1) {
   	/* Let's see what's going on... */
   	curr.ts = get_time();
   	sleep_usec = 0;
   	problems_exist = 0;
   	battery_critical = 0;
   	check_extpower(chgnum);

   • then the charger is connected/disconnected and triggers the extpower_deferred() to be deferred

   EmbeddedController/common/extpower_gpio.c

   Lines 25 to 42 in 8cbd986

   	static void extpower_deferred(void)
   	{
   	int extpower_presence = gpio_get_level(GPIO_AC_PRESENT);
   	if (extpower_presence == debounced_extpower_presence)
   	return;
   	debounced_extpower_presence = extpower_presence;
   	extpower_handle_update(extpower_presence);
   	}
   	DECLARE_DEFERRED(extpower_deferred);
   	void extpower_interrupt(enum gpio_signal signal)
   	{
   	/* Trigger deferred notification of external power change */
   	hook_call_deferred(&extpower_deferred_data,
   	CONFIG_EXTPOWER_DEBOUNCE_MS * MSEC);
   	}

   • charger_task() continues to charger_get_params() which reads from i2c and blocks/yields(?)¹
   • extpower_deferred() runs, calling extpower_handle_update() which updates the mmap and notifies the system
   • charger_task() continues, hitting process_charge_state(), which updates the battery flags mmap with the now-outdated AC-state that was read at the beginning of the iteration
   • on the next iteration the updated state is read and is reverted

   Footnotes

   1. not very familiar with how zephyr scheduling works. this might be off the mark ↩