From 444cc3c8dbba73c3572a2e142f02ebdd60b9ef56 Mon Sep 17 00:00:00 2001
From: Iampete1 <iampete@hotmail.co.uk>
Date: Sun, 9 Mar 2025 18:39:15 +0000
Subject: [PATCH] AP_HAL: add logging of dropped incoming serial data

---
 libraries/AP_HAL/LogStructure.h | 6 ++++--
 libraries/AP_HAL/UARTDriver.cpp | 2 ++
 libraries/AP_HAL/UARTDriver.h   | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_HAL/LogStructure.h b/libraries/AP_HAL/LogStructure.h
index 5749015156..393ca72ce0 100644
--- a/libraries/AP_HAL/LogStructure.h
+++ b/libraries/AP_HAL/LogStructure.h
@@ -11,19 +11,21 @@
 // @Field: TimeUS: Time since system startup
 // @Field: I: instance
 // @Field: Tx: transmitted data rate bytes per second
-// @Field: Rx: received data rate bytes per second
+// @Field: Rx: received data rate bytes per second, this is all incoming data, it may not all be processed by the driver using this port.
+// @Field: RxDp: Data rate of dropped received bytes, ideally should be 0. This is the difference between the received data rate and the processed data rate.
 struct PACKED log_UART {
     LOG_PACKET_HEADER;
     uint64_t time_us;
     uint8_t instance;
     float tx_rate;
     float rx_rate;
+    float rx_drop_rate;
 };
 
 #if HAL_UART_STATS_ENABLED
 #define LOG_STRUCTURE_FROM_HAL                          \
     { LOG_UART_MSG, sizeof(log_UART),                   \
-      "UART","QBff","TimeUS,I,Tx,Rx", "s#BB", "F---" },
+      "UART","QBfff","TimeUS,I,Tx,Rx,RxDp", "s#BBB", "F----" },
 #else
 #define LOG_STRUCTURE_FROM_HAL
 #endif
diff --git a/libraries/AP_HAL/UARTDriver.cpp b/libraries/AP_HAL/UARTDriver.cpp
index 55412be318..53bb68dc57 100644
--- a/libraries/AP_HAL/UARTDriver.cpp
+++ b/libraries/AP_HAL/UARTDriver.cpp
@@ -211,6 +211,7 @@ void AP_HAL::UARTDriver::log_stats(const uint8_t inst, StatsTracker &stats, cons
     // Update tracking
     const uint32_t tx_bytes = stats.tx.update(total_tx_bytes);
     const uint32_t rx_bytes = stats.rx.update(total_rx_bytes);
+    const uint32_t rx_dropped_bytes = stats.rx_dropped.update(get_total_dropped_rx_bytes());
 
     // Assemble struct and log
     struct log_UART pkt {
@@ -219,6 +220,7 @@ void AP_HAL::UARTDriver::log_stats(const uint8_t inst, StatsTracker &stats, cons
         instance : inst,
         tx_rate  : float((tx_bytes * 1000) / dt_ms),
         rx_rate  : float((rx_bytes * 1000) / dt_ms),
+        rx_drop_rate : float((rx_dropped_bytes * 1000) / dt_ms),
     };
     AP::logger().WriteBlock(&pkt, sizeof(pkt));
 }
diff --git a/libraries/AP_HAL/UARTDriver.h b/libraries/AP_HAL/UARTDriver.h
index cf8494f2c9..6a4065cf6f 100644
--- a/libraries/AP_HAL/UARTDriver.h
+++ b/libraries/AP_HAL/UARTDriver.h
@@ -171,6 +171,7 @@ public:
         };
         ByteTracker tx;
         ByteTracker rx;
+        ByteTracker rx_dropped;
     };
 
     // request information on uart I/O for this uart, for @SYS/uarts.txt
@@ -259,6 +260,7 @@ protected:
     // Getters for cumulative tx and rx counts
     virtual uint32_t get_total_tx_bytes() const { return 0; }
     virtual uint32_t get_total_rx_bytes() const { return 0; }
+    virtual uint32_t get_total_dropped_rx_bytes() const { return 0; }
 #endif
 
 private: