Revert "fw/services/light: prime ALS across wake interaction windows"

This reverts commit dcb88c8.

Signed-off-by: Joshua Jun <lets@throw.rocks>

Author: jplexer

src/fw/services/light/service.c

@@ -114,49 +114,8 @@ static uint32_t s_als_cached_level;
 static RtcTicks s_als_cached_ticks;  // 0 = invalid
 #define ALS_CACHE_TTL_TICKS (RTC_TICKS_HZ)  // 1 second
 
-//! Event-gated continuous ALS:
-//!
-//! Wake-related entry points call prv_als_prime_for_interaction(), which (if
-//! not already primed) takes a single ambient_light_prime() refcount and
-//! starts a release timer for ALS_PRIME_HOLDOFF_MS. Each subsequent wake-y
-//! call rearms the timer. When it eventually fires, we drop the prime so the
-//! sensor goes back to idle.
-//!
-//! While primed, the W1160 runs in continuous mode: ALS reads collapse to a
-//! plain register read once one IT has elapsed, and the cache hits more often
-//! because reads are cheap enough that callers don't gate on them. The
-//! holdoff is sized to cover typical multi-wake patterns ("raise wrist, lower,
-//! raise again a few seconds later") so we keep sampling across them rather
-//! than re-paying the first-IT wait per wake.
-static TimerID s_als_prime_release_timer_id;
-static bool s_als_primed;
-#define ALS_PRIME_HOLDOFF_MS (5000)
-
 static void prv_change_state(BacklightState new_state);
 
-//! Timer callback: holdoff expired, drop the prime so the W1160 stops
-//! integrating in the background. Runs on the new_timer task.
-static void prv_als_prime_release_callback(void *data) {
-  mutex_lock(s_mutex);
-  if (s_als_primed) {
-    s_als_primed = false;
-    ambient_light_release();
-  }
-  mutex_unlock(s_mutex);
-}
-
-//! Open or extend an "interaction window" during which the W1160 is held in
-//! continuous-sampling mode. Call from any wake-event-y entry point before
-//! consulting ALS. Caller must hold s_mutex.
-static void prv_als_prime_for_interaction(void) {
-  if (!s_als_primed) {
-    s_als_primed = true;
-    ambient_light_prime();
-  }
-  new_timer_start(s_als_prime_release_timer_id, ALS_PRIME_HOLDOFF_MS,
-                  prv_als_prime_release_callback, NULL, 0 /* flags */);
-}
-
 static uint32_t prv_get_als_level(void) {
   RtcTicks now = rtc_get_ticks();
   const bool cache_valid =
@@ -260,15 +219,6 @@ static void prv_change_brightness(uint8_t new_brightness) {
   // Scale the 0-100% to the maximum value allowed in hardware
   uint8_t scaled_brightness = (new_brightness * (uint16_t)BOARD_CONFIG.backlight_on_percent) / 100U;
 
-  // Bleed-through gate around backlight 0↔on edges: while the LED is
-  // illuminating the cover glass, the W1160 photodiode would latch
-  // contaminated readings even though our cache pins to the pre-on value.
-  // Suspending stops integration entirely, so the chip preserves the last
-  // clean DATA_ALS until we resume. No-op while not primed (driver
-  // composes suspend with the prime refcount).
-  const bool turning_on = (s_current_brightness == 0U) && (new_brightness > 0U);
-  const bool turning_off = (s_current_brightness > 0U) && (new_brightness == 0U);
-
   if (new_brightness == 0U) {
     PBL_ANALYTICS_TIMER_STOP(backlight_on_time_ms);
   } else {
@@ -277,13 +227,7 @@ static void prv_change_brightness(uint8_t new_brightness) {
 
   prv_update_intensity_analytics(scaled_brightness);
 
-  if (turning_on) {
-    ambient_light_suspend();
-  }
   backlight_set_brightness(scaled_brightness);
-  if (turning_off) {
-    ambient_light_resume();
-  }
   s_current_brightness = new_brightness;
 
 #ifdef CONFIG_BACKLIGHT_HAS_COLOR
@@ -386,6 +330,7 @@ static bool prv_light_allowed(void) {
 void light_init(void) {
   s_light_state = LIGHT_STATE_OFF;
   s_current_brightness = 0;
+  s_timer_id = new_timer_create();
   s_num_buttons_down = 0;
   s_user_controlled_state = false;
   s_fade_start_intensity = 0;
@@ -400,13 +345,6 @@ void light_init(void) {
 
   s_als_cached_level = 0;
   s_als_cached_ticks = 0;
-
-  // Create the ALS release timer before the fade timer so existing tests that
-  // pluck the most-recently-created idle timer (test_light.c:149) still pick
-  // up s_timer_id.
-  s_als_prime_release_timer_id = new_timer_create();
-  s_als_primed = false;
-  s_timer_id = new_timer_create();
 }
 
 void light_button_pressed(void) {
@@ -418,8 +356,6 @@ void light_button_pressed(void) {
     s_num_buttons_down = 0;
   }
 
-  prv_als_prime_for_interaction();
-
   // set the state to be on; releasing buttons will start the timer counting down
   if (prv_light_allowed()) {
     prv_change_state(LIGHT_STATE_ON);
@@ -456,8 +392,6 @@ void light_enable_interaction(void) {
     return;
   }
 
-  prv_als_prime_for_interaction();
-
   if (prv_light_allowed()) {
     prv_change_state(LIGHT_STATE_ON_TIMED);
   } else {
@@ -495,7 +429,6 @@ void light_enable_respect_settings(bool enable) {
   s_user_controlled_state = enable;
 
   if (enable) {
-    prv_als_prime_for_interaction();
     if (prv_light_allowed()) {
       prv_change_state(LIGHT_STATE_ON);
     }
@@ -579,7 +512,6 @@ static void prv_light_reset_to_timed_mode(void) {
 
   if (s_user_controlled_state) {
     s_user_controlled_state = false;
-    prv_als_prime_for_interaction();
     if (prv_light_allowed()) {
       prv_change_state(LIGHT_STATE_ON_TIMED);
     }