diff --git a/arch/arm/src/stm32h7/stm32_serial.c b/arch/arm/src/stm32h7/stm32_serial.c
index 75971f1a11..107df66414 100644
--- a/arch/arm/src/stm32h7/stm32_serial.c
+++ b/arch/arm/src/stm32h7/stm32_serial.c
@@ -628,7 +628,6 @@ struct up_dev_s
 #ifdef SERIAL_HAVE_TXDMA
   const unsigned int txdma_channel; /* DMA channel assigned */
   DMA_HANDLE        txdma;          /* currently-open trasnmit DMA stream */
-  sem_t             txdmasem;       /* Indicate TX DMA completion */
 #endif
 
   /* RX DMA state */
@@ -3299,8 +3298,9 @@ static bool up_dma_rxavailable(struct uart_dev_s *dev)
  * Name: up_dma_txcallback
  *
  * Description:
- *   This function clears dma buffer at complete of DMA transfer and wakes up
- *   threads waiting for space in buffer.
+ *   This function clears dma buffer at completion of DMA transfer. It wakes
+ *   up threads waiting for space in buffer and restarts the DMA if there is
+ *   more data to send.
  *
  ****************************************************************************/
 
@@ -3314,11 +3314,7 @@ static void up_dma_txcallback(DMA_HANDLE handle, uint8_t status, void *arg)
    * This is important to free TX buffer space by 'uart_xmitchars_done'.
    */
 
-  if (status & DMA_SCR_HTIE)
-    {
-      priv->dev.dmatx.nbytes += priv->dev.dmatx.length / 2;
-    }
-  else if (status & DMA_SCR_TCIE)
+  if (status & DMA_SCR_TCIE)
     {
       priv->dev.dmatx.nbytes += priv->dev.dmatx.length;
       if (priv->dev.dmatx.nlength)
@@ -3346,11 +3342,13 @@ static void up_dma_txcallback(DMA_HANDLE handle, uint8_t status, void *arg)
         }
     }
 
-  nxsem_post(&priv->txdmasem);
-
   /* Adjust the pointers */
 
   uart_xmitchars_done(&priv->dev);
+
+  /* Send more if availaible */
+
+  up_dma_txavailable(&priv->dev);
 }
 #endif
 
@@ -3369,8 +3367,7 @@ static void up_dma_txavailable(struct uart_dev_s *dev)
 
   /* Only send when the DMA is idle */
 
-  int rv = nxsem_trywait(&priv->txdmasem);
-  if (rv == OK)
+  if (stm32_dmaresidual(priv->txdma) == 0)
     {
       uart_xmitchars_dma(dev);
     }