Re: [PATCH 3/3] hw/char: cadence_uart: Move clock/reset check to uart_can_receive()

[Philippe Mathieu-Daudé]

On 8/23/21 4:08 AM, Bin Meng wrote:
> Currently the clock/reset check is done in uart_receive(), but we
> can move the check to uart_can_receive() which is earlier.
> 
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> 
> ---
> 
>  hw/char/cadence_uart.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index 154be34992..7326445385 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -235,6 +235,12 @@ static void uart_parameters_setup(CadenceUARTState *s)
>  static int uart_can_receive(void *opaque)
>  {
>      CadenceUARTState *s = opaque;
> +
> +    /* ignore characters when unclocked or in reset */
> +    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
> +        return 0;
> +    }
> +
>      int ret = MAX(CADENCE_UART_RX_FIFO_SIZE, CADENCE_UART_TX_FIFO_SIZE);
>      uint32_t ch_mode = s->r[R_MR] & UART_MR_CHMODE;
>  
> @@ -358,11 +364,6 @@ static void uart_receive(void *opaque, const uint8_t 
> *buf, int size)
>      CadenceUARTState *s = opaque;
>      uint32_t ch_mode = s->r[R_MR] & UART_MR_CHMODE;
>  
> -    /* ignore characters when unclocked or in reset */
> -    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
> -        return;
> -    }
> -
>      if (ch_mode == NORMAL_MODE || ch_mode == ECHO_MODE) {
>          uart_write_rx_fifo(opaque, buf, size);
>      }
> 

Almost the same I just sent in patch #2 (minor you declare variables
mid-scope). Drop #2 and use that (or untested snippet) directly instead.