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

[Bin Meng]

On Mon, Aug 23, 2021 at 4:14 PM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> 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?
>

Sorry I don't get it. This patch is for the Tx path, while patch #3 is
for the Rx path.

> -- >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);

Regards,
Bin