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| author | Romain Izard <romain.izard.pro@gmail.com> | 2017-09-28 11:46:27 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-04 10:14:16 +0200 |
| commit | ea04f82a0c7f2739071cc9ac4a0ca57b3bddef7b (patch) | |
| tree | f60b3c5e20e307e9912bf493fc4005117af5319e /drivers/tty/serial/atmel_serial.c | |
| parent | fa2abb03637a55288b22082d3d679db4fe74112a (diff) | |
| download | linux-ea04f82a0c7f2739071cc9ac4a0ca57b3bddef7b.tar.gz linux-ea04f82a0c7f2739071cc9ac4a0ca57b3bddef7b.tar.bz2 linux-ea04f82a0c7f2739071cc9ac4a0ca57b3bddef7b.zip | |
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: Romain Izard <romain.izard.pro@gmail.com>
Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/atmel_serial.c')
| -rw-r--r-- | drivers/tty/serial/atmel_serial.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 04e55f010894..82d9c8eae04f 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -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); |