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Date:   Mon, 28 Nov 2022 22:21:23 +0800
From:   Jisheng Zhang <jszhang@kernel.org>
To:     Jiri Slaby <jirislaby@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>, Conor Dooley <conor@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ilpo =?utf-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>,
        linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH v2 2/9] serial: bflb_uart: add Bouffalolab UART Driver
Message-ID: <Y4TD48v84CJcMS+S@xhacker>
References: <20221127132448.4034-1-jszhang@kernel.org>
 <20221127132448.4034-3-jszhang@kernel.org>
 <c0406076-04e1-6b81-1bba-ac684516d898@kernel.org>
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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
>