diff --git a/components/driver/uart.c b/components/driver/uart.c
index 2b9642f25..d839a062f 100644
--- a/components/driver/uart.c
+++ b/components/driver/uart.c
@@ -858,7 +858,6 @@ static int uart_tx_all(uart_port_t uart_num, const char* src, size_t size, bool
             offset += send_size;
             uart_enable_tx_intr(uart_num, 1, UART_EMPTY_THRESH_DEFAULT);
         }
-        xSemaphoreGive(p_uart_obj[uart_num]->tx_mux);
     } else {
         while(size) {
             //semaphore for tx_fifo available