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

[Alistair Francis]

On Mon, Aug 23, 2021 at 12:11 PM Bin Meng <bmeng.cn@gmail.com> 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;
> +    }

Should we log a guest error here?

Alistair

> +
>      if ((s->r[R_CR] & UART_CR_TX_DIS) || !(s->r[R_CR] & UART_CR_TX_EN)) {
>          return;
>      }
> --
> 2.25.1
>
>