hw/char/stm32f2xx_usart: Do not update data register when device is disabled

When the device is disabled, the internal circuitry keeps the data
register loaded and doesn't update it.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20190104182057.8778-1-philmd@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/char/stm32f2xx_usart.c b/hw/char/stm32f2xx_usart.c
index f3363a2952dbee26b411232769a04e6e1a2e9579..10392c70e2ddea0caea8b1d7eeb10b507126cb1e 100644 (file)
--- a/hw/char/stm32f2xx_usart.c
+++ b/hw/char/stm32f2xx_usart.c
@@ -53,14 +53,13 @@ static void stm32f2xx_usart_receive(void *opaque, const uint8_t *buf, int size)
 {
     STM32F2XXUsartState *s = opaque;
 
-    s->usart_dr = *buf;
-
     if (!(s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_RE)) {
         /* USART not enabled - drop the chars */
         DB_PRINT("Dropping the chars\n");
         return;
     }
 
+    s->usart_dr = *buf;
     s->usart_sr |= USART_SR_RXNE;
 
     if (s->usart_cr1 & USART_CR1_RXNEIE) {