From b5435d6a2451017f21ee0f360215d4b92443d5c6 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Fri, 31 Jan 2020 11:20:40 +1100
Subject: [PATCH] HAL_ChibiOS: use recursive mutex for RCInput

---
 libraries/AP_HAL_ChibiOS/RCInput.cpp | 11 +++++------
 libraries/AP_HAL_ChibiOS/RCInput.h   |  2 +-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/libraries/AP_HAL_ChibiOS/RCInput.cpp b/libraries/AP_HAL_ChibiOS/RCInput.cpp
index 1351ac92bb..9450a4acc4 100644
--- a/libraries/AP_HAL_ChibiOS/RCInput.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCInput.cpp
@@ -73,13 +73,12 @@ bool RCInput::new_input()
     if (!_init) {
         return false;
     }
-    if (!rcin_mutex.take_nonblocking()) {
-        return false;
+    bool valid;
+    {
+        WITH_SEMAPHORE(rcin_mutex);
+        valid = _rcin_timestamp_last_signal != _last_read;
+        _last_read = _rcin_timestamp_last_signal;
     }
-    bool valid = _rcin_timestamp_last_signal != _last_read;
-
-    _last_read = _rcin_timestamp_last_signal;
-    rcin_mutex.give();
 
 #if HAL_RCINPUT_WITH_AP_RADIO
     if (!_radio_init) {
diff --git a/libraries/AP_HAL_ChibiOS/RCInput.h b/libraries/AP_HAL_ChibiOS/RCInput.h
index 1751ea842d..7f3de7d419 100644
--- a/libraries/AP_HAL_ChibiOS/RCInput.h
+++ b/libraries/AP_HAL_ChibiOS/RCInput.h
@@ -63,7 +63,7 @@ private:
 
     uint64_t _last_read;
     uint8_t _num_channels;
-    Semaphore rcin_mutex;
+    HAL_Semaphore_Recursive rcin_mutex;
     int16_t _rssi = -1;
     uint32_t _rcin_timestamp_last_signal;
     bool _init;