Re: [PATCH v2 2/9] serial: bflb_uart: add Bouffalolab UART Driver

[Jisheng Zhang <jszhang@kernel.org>]

On Mon, Nov 28, 2022 at 07:10:41AM +0100, Jiri Slaby wrote:
> On 27. 11. 22, 14:24, Jisheng Zhang wrote:
> > +static void bflb_uart_tx_chars(struct uart_port *port)
> 
> Again:
> 
> Are you unable to use the TX helper? If so:

You know serial subsystem better than me, may I ask for more
details? For example,
Besides uart_xmit_advance(), do you expect other TX helpers? If yes,
can you please list them?

> * why?
> * use uart_advance_xmit() at least.

Do you mean uart_xmit_advance()? in the do while loop below?

I'm not sure I understand the meaning, correct me If I misunderstand
something.

thanks
> 
> > +{
> > +	struct circ_buf *xmit = &port->state->xmit;
> > +	unsigned int count;
> > +
> > +	if (port->x_char) {
> > +		/* Send special char - probably flow control */
> > +		wrl(port, UART_FIFO_WDATA, port->x_char);
> > +		port->x_char = 0;
> > +		port->icount.tx++;
> > +		return;
> > +	}
> > +
> > +	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
> > +		bflb_uart_stop_tx(port);
> > +		return;
> > +	}
> > +
> > +	count = BFLB_UART_TX_FIFO_TH;
> > +	do {
> > +		wrl(port, UART_FIFO_WDATA, xmit->buf[xmit->tail]);
> > +		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> > +		port->icount.tx++;
> > +		if (uart_circ_empty(xmit))
> > +			break;
> > +	} while (--count > 0);
> > +
> > +	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> > +		uart_write_wakeup(port);
> > +
> > +	if (uart_circ_empty(xmit))
> > +		bflb_uart_stop_tx(port);
> > +}
> 
> -- 
> js
> suse labs
>