deep_sleep: on S2 disable the brown out detector before deep sleeping

On S2 the brown out detector would occasionally trigger erroneously during deep sleep.

Disable it before sleeping to circumvent this issue.

Closes https://github.com/espressif/esp-idf/issues/6179

components/esp32/include/esp32/brownout.h

@@ -16,6 +16,16 @@
 #ifndef __ESP_BROWNOUT_H
 #define __ESP_BROWNOUT_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void esp_brownout_init(void);
 
-#endif
+void esp_brownout_disable(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

components/esp32s2/include/esp32s2/brownout.h

@@ -1,4 +1,4 @@
-// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+// Copyright 2015-2021 Espressif Systems (Shanghai) PTE LTD
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ extern "C" {
 
 void esp_brownout_init(void);
 
+void esp_brownout_disable(void);
+
 #ifdef __cplusplus
 }
 #endif

components/esp32s2/sleep_modes.c

@@ -26,6 +26,7 @@
 #include "esp32s2/rom/rtc.h"
 #include "esp32s2/rom/uart.h"
 #include "esp32s2/rom/ets_sys.h"
+#include "esp32s2/brownout.h"
 #include "soc/cpu.h"
 #include "soc/rtc.h"
 #include "soc/spi_periph.h"
@@ -229,6 +230,10 @@ static uint32_t IRAM_ATTR esp_sleep_start(uint32_t pd_flags)
 
 void IRAM_ATTR esp_deep_sleep_start(void)
 {
+    /* Due to hardware limitations, on S2 the brownout detector sometimes trigger during deep sleep
+       to circumvent this we disable the brownout detector before sleeping  */
+    esp_brownout_disable();
+
     // record current RTC time
     s_config.rtc_ticks_at_sleep_start = rtc_time_get();
     esp_sync_counters_rtc_and_frc();

components/esp_common/src/brownout.c

@@ -73,3 +73,18 @@ void esp_brownout_init(void)
 
     brownout_hal_intr_enable(true);
 }
+
+void esp_brownout_disable(void)
+{
+    brownout_hal_config_t cfg = {
+        .enabled = false,
+    };
+
+    brownout_hal_config(&cfg);
+
+#ifndef SOC_BROWNOUT_RESET_SUPPORTED
+    brownout_hal_intr_enable(false);
+
+    rtc_isr_deregister(rtc_brownout_isr_handler, NULL);
+#endif // not SOC_BROWNOUT_RESET_SUPPORTED
+}