Commit ea04f82a authored by Romain Izard's avatar Romain Izard Committed by Greg Kroah-Hartman
Browse files

tty/serial: atmel: Prevent a warning on suspend 



The atmel serial port driver reported the following warning on suspend:
atmel_usart f8020000.serial: ttyS1: Unable to drain transmitter

As the ATMEL_US_TXEMPTY status bit in ATMEL_US_CSR is always cleared
when the transmitter is disabled, we need to know the transmitter's
state to return the real fifo state. And as ATMEL_US_CR is write-only,
it is necessary to save the state of the transmitter in a local
variable, and update the variable when TXEN and TXDIS is written in
ATMEL_US_CR.

After those changes, atmel_tx_empty can return "empty" on suspend, the
warning in uart_suspend_port disappears, and suspending is 20ms shorter
for each enabled Atmel serial port.

Signed-off-by: default avatarRomain Izard <romain.izard.pro@gmail.com>
Tested-by: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: default avatarRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fa2abb03

drivers/tty/serial/atmel_serial.c

+13 −0
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ struct atmel_uart_port { 
	bool			has_hw_timer;

	struct timer_list	uart_timer;



	bool			tx_stopped;

	bool			suspended;

	unsigned int		pending;

	unsigned int		pending_status;
@@ -380,6 +381,10 @@ static int atmel_config_rs485(struct uart_port *port, 
 */

static u_int atmel_tx_empty(struct uart_port *port)

{

	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);



	if (atmel_port->tx_stopped)

		return TIOCSER_TEMT;

	return (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXEMPTY) ?

		TIOCSER_TEMT :

		0;
@@ -485,6 +490,7 @@ static void atmel_stop_tx(struct uart_port *port) 
	 * is fully transmitted.

	 */

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS);

	atmel_port->tx_stopped = true;



	/* Disable interrupts */

	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
@@ -521,6 +527,7 @@ static void atmel_start_tx(struct uart_port *port) 


	/* re-enable the transmitter */

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);

	atmel_port->tx_stopped = false;

}



/*
@@ -1843,6 +1850,7 @@ static int atmel_startup(struct uart_port *port) 
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);

	/* enable xmit & rcvr */

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);

	atmel_port->tx_stopped = false;



	setup_timer(&atmel_port->uart_timer,

			atmel_uart_timer_callback,
@@ -2099,6 +2107,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, 


	/* disable receiver and transmitter */

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXDIS);

	atmel_port->tx_stopped = true;



	/* mode */

	if (port->rs485.flags & SER_RS485_ENABLED) {
@@ -2184,6 +2193,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, 
	atmel_uart_writel(port, ATMEL_US_BRGR, quot);

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);

	atmel_port->tx_stopped = false;



	/* restore interrupts */

	atmel_uart_writel(port, ATMEL_US_IER, imr);
@@ -2427,6 +2437,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) 


	/* Make sure that tx path is actually able to send characters */

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);

	atmel_port->tx_stopped = false;



	uart_console_write(port, s, count, atmel_console_putchar);
@@ -2488,6 +2499,7 @@ static int __init atmel_console_setup(struct console *co, char *options) 
{

	int ret;

	struct uart_port *port = &atmel_ports[co->index].uart;

	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	int baud = 115200;

	int bits = 8;

	int parity = 'n';
@@ -2505,6 +2517,7 @@ static int __init atmel_console_setup(struct console *co, char *options) 
	atmel_uart_writel(port, ATMEL_US_IDR, -1);

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);

	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);

	atmel_port->tx_stopped = false;



	if (options)

		uart_parse_options(options, &baud, &parity, &bits, &flow);

CRA Git | Maintained and supported by SUSTech CRA and CCSE