Re: [PATCH 2/3] hw/char: cadence_uart: Disable transmit when input clock is disabled

[Philippe Mathieu-Daudé]

On 8/23/21 4:08 AM, Bin Meng wrote:
> At present when input clock is disabled, any character transmitted
> to tx fifo can still show on the serial line, which is wrong.
> 
> Fixes: b636db306e06 ("hw/char/cadence_uart: add clock support")
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
> 
>  hw/char/cadence_uart.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index b4b5e8a3ee..154be34992 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -327,6 +327,11 @@ static gboolean cadence_uart_xmit(void *do_not_use, 
> GIOCondition cond,
>  static void uart_write_tx_fifo(CadenceUARTState *s, const uint8_t *buf,
>                                 int size)
>  {
> +    /* ignore characters when unclocked or in reset */
> +    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
> +        return;
> +    }

Incorrect handler?

-- >8 --
diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index b4b5e8a3ee0..4f096222f52 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -235,8 +235,16 @@ static void uart_parameters_setup(CadenceUARTState *s)
 static int uart_can_receive(void *opaque)
 {
     CadenceUARTState *s = opaque;
-    int ret = MAX(CADENCE_UART_RX_FIFO_SIZE, CADENCE_UART_TX_FIFO_SIZE);
-    uint32_t ch_mode = s->r[R_MR] & UART_MR_CHMODE;
+    int ret;
+    uint32_t ch_mode;
+
+    /* ignore characters when unclocked or in reset */
+    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
+        return 0;
+    }
+
+    ret = MAX(CADENCE_UART_RX_FIFO_SIZE, CADENCE_UART_TX_FIFO_SIZE);
+    ch_mode = s->r[R_MR] & UART_MR_CHMODE;

     if (ch_mode == NORMAL_MODE || ch_mode == ECHO_MODE) {
         ret = MIN(ret, CADENCE_UART_RX_FIFO_SIZE - s->rx_count);
---