Fix RP2040 idle

Don't idle from main if we scheduled an interrupt for 0 ticks in
the future.

Have RP2040 detect wakes that happen between setting the timer and
the idle call.

Fixes #7361

Author: tannewt

main.c

@@ -716,9 +716,15 @@ STATIC bool run_code_py(safe_mode_t safe_mode, bool *simulate_reset) {
 
             // time_to_next_change is in ms and ticks are slightly shorter so
             // we'll undersleep just a little. It shouldn't matter.
-            port_interrupt_after_ticks(time_to_next_change);
-            #endif
+            if (time_to_next_change > 0) {
+                port_interrupt_after_ticks(time_to_next_change);
+                port_idle_until_interrupt();
+            }
+            #else
+            // No status LED can we sleep until we are interrupted by some
+            // interaction.
             port_idle_until_interrupt();
+            #endif
         }
     }
 

ports/raspberrypi/supervisor/port.c

@@ -257,6 +257,7 @@ uint32_t port_get_saved_word(void) {
 }
 
 static volatile bool ticks_enabled;
+static volatile bool _woken_up;
 
 uint64_t port_get_raw_ticks(uint8_t *subticks) {
     uint64_t microseconds = time_us_64();
@@ -268,6 +269,7 @@ STATIC void _tick_callback(uint alarm_num) {
         supervisor_tick();
         hardware_alarm_set_target(0, delayed_by_us(get_absolute_time(), 977));
     }
+    _woken_up = true;
 }
 
 // Enable 1/1024 second tick.
@@ -291,11 +293,12 @@ void port_interrupt_after_ticks(uint32_t ticks) {
     if (!ticks_enabled) {
         hardware_alarm_set_target(0, delayed_by_us(get_absolute_time(), ticks * 977));
     }
+    _woken_up = false;
 }
 
 void port_idle_until_interrupt(void) {
     common_hal_mcu_disable_interrupts();
-    if (!background_callback_pending() && !tud_task_event_ready()) {
+    if (!background_callback_pending() && !tud_task_event_ready() && !_woken_up) {
         __DSB();
         __WFI();
     }