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Message-Id: <20221121202724.1708460-1-michael@walle.cc>
Date: Mon, 21 Nov 2022 21:27:24 +0100
From: Michael Walle <michael@...le.cc>
To: jirislaby@...nel.org
Cc: afaerber@...e.de, alexandre.belloni@...tlin.com,
claudiu.beznea@...rochip.com, festevam@...il.com,
gregkh@...uxfoundation.org, ilpo.jarvinen@...ux.intel.com,
kernel@...gutronix.de, linux-imx@....com,
linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
liviu.dudau@....com, lorenzo.pieralisi@....com, mani@...nel.org,
nicolas.ferre@...rochip.com, richard.genoud@...il.com,
s.hauer@...gutronix.de, shawnguo@...nel.org, sudeep.holla@....com,
tklauser@...tanz.ch, vz@...ia.com
Subject: Re: [PATCH v5 2/3] tty: serial: use uart_port_tx() helper
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Hi Jiri,
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index bd07f79a2df9..a6b4d30c5888 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -824,30 +824,14 @@ static void atmel_rx_chars(struct uart_port *port)
> */
> static void atmel_tx_chars(struct uart_port *port)
> {
> - struct circ_buf *xmit = &port->state->xmit;
> struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> + bool pending;
> + u8 ch;
>
> - if (port->x_char &&
> - (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY)) {
> - atmel_uart_write_char(port, port->x_char);
> - port->icount.tx++;
> - port->x_char = 0;
> - }
> - if (uart_circ_empty(xmit) || uart_tx_stopped(port))
> - return;
> -
> - while (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY) {
> - atmel_uart_write_char(port, xmit->buf[xmit->tail]);
> - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> - port->icount.tx++;
> - if (uart_circ_empty(xmit))
> - break;
> - }
> -
> - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> - uart_write_wakeup(port);
> -
> - if (!uart_circ_empty(xmit)) {
> + pending = uart_port_tx(port, ch,
> + atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY,
> + atmel_uart_write_char(port, ch));
> + if (pending) {
> /* we still have characters to transmit, so we should continue
> * transmitting them when TX is ready, regardless of
> * mode or duplexity
This will break serial output for the userspace on my board
(arch/arm/boot/dts/lan966x-kontron-kswitch-d10-mmt*dts). The uart_port_tx()
helper will call __port->ops->stop_tx(__port) if uart_circ_chars_pending()
returns 0. But the code above, doesn't do that. In fact, removing the
stop_tx() call in the helper macro, will fix the console output.
Any ideas how to fix that?
-michael
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