From d52ee81b3a0704e8e1e40b6acf3ff03199905303 Mon Sep 17 00:00:00 2001
From: Giovanni Di Sirio <gdisirio@gmail.com>
Date: Sun, 19 Apr 2015 07:49:28 +0000
Subject: Fixed bug #584.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7905 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/hal/ports/STM32/LLD/USARTv2/uart_lld.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

(limited to 'os/hal/ports/STM32/LLD/USARTv2/uart_lld.c')

diff --git a/os/hal/ports/STM32/LLD/USARTv2/uart_lld.c b/os/hal/ports/STM32/LLD/USARTv2/uart_lld.c
index 61cbe3ac7..1cce68503 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/uart_lld.c
+++ b/os/hal/ports/STM32/LLD/USARTv2/uart_lld.c
@@ -176,11 +176,10 @@ static void usart_start(UARTDriver *uartp) {
   u->CR2 = uartp->config->cr2 | USART_CR2_LBDIE;
   u->CR3 = uartp->config->cr3 | USART_CR3_DMAT | USART_CR3_DMAR |
                                 USART_CR3_EIE;
-  if (uartp->config->txend2_cb == NULL)
-    cr1 = USART_CR1_UE | USART_CR1_PEIE | USART_CR1_TE | USART_CR1_RE;
-  else
-    cr1 = USART_CR1_UE | USART_CR1_PEIE | USART_CR1_TE | USART_CR1_RE |
-          USART_CR1_TCIE;
+
+  /* Mustn't ever set TCIE here - if done, it causes an immediate
+     interrupt.*/
+  cr1 = USART_CR1_UE | USART_CR1_PEIE | USART_CR1_TE | USART_CR1_RE;
   u->CR1 = uartp->config->cr1 | cr1;
 
   /* Starting the receiver idle loop.*/
@@ -246,6 +245,12 @@ static void uart_lld_serve_tx_end_irq(UARTDriver *uartp, uint32_t flags) {
 
   dmaStreamDisable(uartp->dmatx);
 
+  /* Only enable TC interrupt if there's a callback attached to it.
+     We have to do it here, rather than earlier, because TC flag is set
+     until transmission starts.*/
+  if (uartp->config->txend2_cb != NULL)
+    uartp->usart->CR1 |= USART_CR1_TCIE;
+
   /* A callback is generated, if enabled, after a completed transfer.*/
   uartp->txstate = UART_TX_COMPLETE;
   if (uartp->config->txend1_cb != NULL)
@@ -265,6 +270,7 @@ static void uart_lld_serve_tx_end_irq(UARTDriver *uartp, uint32_t flags) {
 static void serve_usart_irq(UARTDriver *uartp) {
   uint32_t isr;
   USART_TypeDef *u = uartp->usart;
+  uint32_t cr1 = u->CR1;
   
   /* Reading and clearing status.*/
   isr = u->ISR;
@@ -275,7 +281,11 @@ static void serve_usart_irq(UARTDriver *uartp) {
     if (uartp->config->rxerr_cb != NULL)
       uartp->config->rxerr_cb(uartp, translate_errors(isr));
   }
-  if (isr & USART_ISR_TC) {
+
+  if ((isr & USART_ISR_TC) && (cr1 & USART_CR1_TCIE)) {
+    /* TC interrupt disabled.*/
+    u->CR1 = cr1 & ~USART_CR1_TCIE;
+
     /* End of transmission, a callback is generated.*/
     if (uartp->config->txend2_cb != NULL)
       uartp->config->txend2_cb(uartp);
-- 
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