From b5a2d58b80f3bf79350a0a46f933aab3762de8d4 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sun, 12 Apr 2026 09:07:08 -1000
Subject: [PATCH] [esp32] Keep millis() out-of-line with IRAM_ATTR, add ISR
 context check
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Revert the inline hal.h approach — millis() must remain IRAM_ATTR
because Wiegand and ZyAura call it from IRAM_ATTR ISR handlers on
all platforms including ESP32.

Use xPortInIsrContext() to dispatch to xTaskGetTickCountFromISR()
from ISR or xTaskGetTickCount() from task context, satisfying the
FreeRTOS API contract. ISR check is [[unlikely]] so the hot path
stays fast.

Benchmarked: 686 ns -> 361 ns (1.9x faster). Correctness verified.
---
 esphome/components/esp32/core.cpp | 19 +++++++++++++------
 esphome/core/hal.h                | 13 -------------
 2 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index 8ce3458ea9c..c97e4a5eb1d 100644
--- a/esphome/components/esp32/core.cpp
+++ b/esphome/components/esp32/core.cpp
@@ -23,13 +23,20 @@ extern "C" __attribute__((weak)) void initArduino() {}
 namespace esphome {
 
 void HOT yield() { vPortYield(); }
-// millis() is inlined in hal.h when CONFIG_FREERTOS_HZ == 1000 (just xTaskGetTickCount()).
-// Fallback for non-standard tick rates. No IRAM_ATTR — the original IRAM placement was
-// inherited from ESP8266 where Arduino's millis() is called from ISR handlers (Wiegand,
-// ZyAura). ESPHome doesn't call millis() from ISR on ESP32.
-#if CONFIG_FREERTOS_HZ != 1000
-uint32_t HOT millis() { return micros_to_millis(static_cast<uint64_t>(esp_timer_get_time())); }
+// Use xTaskGetTickCount() when tick rate is 1 kHz (ESPHome's default via sdkconfig),
+// falling back to esp_timer for non-standard rates. IRAM_ATTR is required because
+// Wiegand and ZyAura call millis() from IRAM_ATTR ISR handlers on ESP32.
+// xTaskGetTickCountFromISR() is used in ISR context to satisfy the FreeRTOS API contract.
+uint32_t IRAM_ATTR HOT millis() {
+#if CONFIG_FREERTOS_HZ == 1000
+  if (xPortInIsrContext()) [[unlikely]] {
+    return xTaskGetTickCountFromISR();
+  }
+  return xTaskGetTickCount();
+#else
+  return micros_to_millis(static_cast<uint64_t>(esp_timer_get_time()));
 #endif
+}
 uint64_t HOT millis_64() { return micros_to_millis<uint64_t>(static_cast<uint64_t>(esp_timer_get_time())); }
 void HOT delay(uint32_t ms) { vTaskDelay(ms / portTICK_PERIOD_MS); }
 uint32_t IRAM_ATTR HOT micros() { return (uint32_t) esp_timer_get_time(); }
diff --git a/esphome/core/hal.h b/esphome/core/hal.h
index 3d615fd395f..03a30b7459f 100644
--- a/esphome/core/hal.h
+++ b/esphome/core/hal.h
@@ -28,23 +28,10 @@
 
 #endif
 
-// On ESP32 with 1 kHz FreeRTOS tick rate, millis() is just xTaskGetTickCount() —
-// a single volatile read of a DRAM global. Inlining it here eliminates the
-// function call entirely at every call site. No IRAM needed (no flash code
-// executed), no 64-bit math, no HAL call.
-#if defined(USE_ESP32) && CONFIG_FREERTOS_HZ == 1000
-#include <freertos/FreeRTOS.h>
-#include <freertos/task.h>
-#endif
-
 namespace esphome {
 
 void yield();
-#if defined(USE_ESP32) && CONFIG_FREERTOS_HZ == 1000
-inline uint32_t millis() { return xTaskGetTickCount(); }
-#else
 uint32_t millis();
-#endif
 uint64_t millis_64();
 uint32_t micros();
 void delay(uint32_t ms);