From 63a0b2ffa9f8f54cc35074fcc3f05e8f13cec8d3 Mon Sep 17 00:00:00 2001
From: Technobly <technobly@gmail.com>
Date: Mon, 15 Jul 2024 20:47:29 -0500
Subject: [PATCH 1/2] [rtl872x] fixes DMA enabled USART flush

---
 hal/src/rtl872x/usart_hal.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hal/src/rtl872x/usart_hal.cpp b/hal/src/rtl872x/usart_hal.cpp
index acd31451d7..20fca93b6c 100644
--- a/hal/src/rtl872x/usart_hal.cpp
+++ b/hal/src/rtl872x/usart_hal.cpp
@@ -288,6 +288,7 @@ class Usart {
         txBuffer_.reset();
         curTxCount_ = 0;
         transmitting_ = false;
+        busy_ = false;
         receiving_ = false;
         state_ = HAL_USART_STATE_DISABLED;
         return SYSTEM_ERROR_NONE;
@@ -300,6 +301,7 @@ class Usart {
         dataInFlight(true /* commit */);
         CHECK(disable(false));
         transmitting_ = false;
+        busy_ = false;
         receiving_ = 0;
         rxBuffer_.prune();
         txBuffer_.reset();
@@ -344,7 +346,7 @@ class Usart {
             }
             {
                 AtomicBlock atomic(this);
-                if (!isEnabled() || txBuffer_.empty()) {
+                if ((!isEnabled() || txBuffer_.empty()) && !busy_) {
                     break;
                 }
             }
@@ -572,6 +574,7 @@ class Usart {
                 } else {
                     UART_TXDMACmd(uartInstance, ENABLE);
                     BaseType_t yield = pdFALSE;
+                    uart->busy_ = false;
                     if (xEventGroupSetBitsFromISR(uart->evGroup_, HAL_USART_PVT_EVENT_WRITABLE, &yield) != pdFAIL) {
                         portYIELD_FROM_ISR(yield);
                     }
@@ -618,6 +621,7 @@ class Usart {
               curTxCount_(0),
               state_(HAL_USART_STATE_DISABLED),
               transmitting_(false),
+              busy_(false),
               receiving_(false),
               configured_(false),
               index_(index),
@@ -831,12 +835,15 @@ class Usart {
                 curTxCount_ = consumable;
                 GDMA_Init(txDmaInitStruct_.GDMA_Index, txDmaInitStruct_.GDMA_ChNum, &txDmaInitStruct_);
                 GDMA_Cmd(txDmaInitStruct_.GDMA_Index, txDmaInitStruct_.GDMA_ChNum, ENABLE);
+                busy_ = true;
+                UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);
             } else {
                 // LOG UART doesn't support DMA transmission
                 consumable = std::min(MAX_UART_FIFO_SIZE, consumable);
                 auto ptr = txBuffer_.consume(consumable);
                 for (size_t i = 0; i < consumable; i++, ptr++) {
                     UART_CharPut(uartInstance, *ptr);
+                    UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);
                 }
                 curTxCount_ = consumable;
                 UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);
@@ -982,6 +989,7 @@ class Usart {
 
     volatile hal_usart_state_t state_;
     volatile bool transmitting_;
+    volatile bool busy_;
     volatile bool receiving_;
     bool configured_;
 

From 81e85fce0a252fae5b695d8a7eb102344faaf89a Mon Sep 17 00:00:00 2001
From: Technobly <technobly@gmail.com>
Date: Tue, 16 Jul 2024 12:22:11 -0500
Subject: [PATCH 2/2] review comments

---
 hal/src/rtl872x/usart_hal.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hal/src/rtl872x/usart_hal.cpp b/hal/src/rtl872x/usart_hal.cpp
index 20fca93b6c..54354a9516 100644
--- a/hal/src/rtl872x/usart_hal.cpp
+++ b/hal/src/rtl872x/usart_hal.cpp
@@ -341,7 +341,7 @@ class Usart {
     ssize_t flush() {
         CHECK_TRUE(isEnabled(), SYSTEM_ERROR_INVALID_STATE);
         while (true) {
-            while (transmitting_) {
+            while (transmitting_ || busy_) {
                 // FIXME: busy loop
             }
             {
@@ -472,6 +472,7 @@ class Usart {
         if (event & HAL_USART_PVT_EVENT_WRITABLE) {
             if (space() <= 0) {
                 TxLock lk(this);
+                xEventGroupClearBits(evGroup_, HAL_USART_PVT_EVENT_WRITABLE);
                 UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);
                 // Temporarily disable TX DMA, otherwise, the TX FIFO won't be empty until all data is transferred by DMA.
                 UART_TXDMACmd(uartInstance, DISABLE);
@@ -574,7 +575,9 @@ class Usart {
                 } else {
                     UART_TXDMACmd(uartInstance, ENABLE);
                     BaseType_t yield = pdFALSE;
-                    uart->busy_ = false;
+                    if (!uart->transmitting_) {
+                        uart->busy_ = false; // All bytes sent if no new DMA transfers are in progress
+                    }
                     if (xEventGroupSetBitsFromISR(uart->evGroup_, HAL_USART_PVT_EVENT_WRITABLE, &yield) != pdFAIL) {
                         portYIELD_FROM_ISR(yield);
                     }
@@ -843,7 +846,6 @@ class Usart {
                 auto ptr = txBuffer_.consume(consumable);
                 for (size_t i = 0; i < consumable; i++, ptr++) {
                     UART_CharPut(uartInstance, *ptr);
-                    UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);
                 }
                 curTxCount_ = consumable;
                 UART_INTConfig(uartInstance, RUART_IER_ETBEI, ENABLE);