Re: [PATCH v3 08/15] serial: 8250_mxpcie: speed up TX using memory-mapped FIFO window

[Jiri Slaby <jirislaby@kernel.org>]

On 09. 07. 26, 7:33, Crescent Hsieh wrote:
...
> --- a/drivers/tty/serial/8250/8250_mxpcie.c
> +++ b/drivers/tty/serial/8250/8250_mxpcie.c
...
> @@ -318,6 +320,37 @@ static u16 mxpcie8250_rx_chars(struct uart_8250_port *up, u16 lsr)
>   	return serial8250_rx_chars(up, lsr);
>   }
>   
> +static void mxpcie8250_tx_chars(struct uart_8250_port *up)
> +{
> +	struct uart_port *port = &up->port;
> +	struct tty_port *tport = &port->state->port;
> +	unsigned int count, txsize;
> +	unsigned char c;
> +
> +	if (port->x_char) {
> +		uart_xchar_out(port, UART_TX);
> +		return;
> +	}
> +	if (uart_tx_stopped(port) || kfifo_is_empty(&tport->xmit_fifo)) {
> +		port->ops->stop_tx(port);
> +		return;
> +	}
> +	txsize = serial_in(up, MOXA_PUART_TX_FIFO_CNT);
> +	count = min(kfifo_len(&tport->xmit_fifo), port->fifosize - txsize);
> +
> +	for (unsigned int i = 0; i < count; ++i) {
> +		if (!uart_fifo_get(port, &c))
> +			break;
> +
> +		serial_out(up, MOXA_PUART_TX_FIFO_MEM + i, c);
> +	}
> +	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
> +		uart_write_wakeup(port);
> +
> +	if (kfifo_is_empty(&tport->xmit_fifo) && !(up->capabilities & UART_CAP_RPM))
> +		port->ops->stop_tx(port);

What's the reason not to use uart_port_tx() et al.?

thanks,
-- 
js
suse labs