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Groups > linux.kernel > #1734794
| From | Nicolas Ferre <nicolas.ferre@microchip.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend |
| Date | 2017-09-19 12:20 +0200 |
| Message-ID | <urnNf-47l-3@gated-at.bofh.it> (permalink) |
| References | <upZtD-3TS-5@gated-at.bofh.it> <upZtD-3TS-7@gated-at.bofh.it> |
| Organization | microchip |
On 15/09/2017 at 16:04, Romain Izard wrote:
> 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>
on sama5d2 Xplained.
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> ---
> drivers/tty/serial/atmel_serial.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index 7551cab438ff..783af6648be0 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);
> @@ -492,6 +498,7 @@ static void atmel_stop_tx(struct uart_port *port)
> if ((port->rs485.flags & SER_RS485_ENABLED) &&
> !(port->rs485.flags & SER_RS485_RX_DURING_TX))
> atmel_start_rx(port);
> +
> }
>
> /*
> @@ -521,6 +528,7 @@ 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;
> }
>
> /*
> @@ -1866,6 +1874,7 @@ 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,
> @@ -2122,6 +2131,7 @@ 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) {
> @@ -2207,6 +2217,7 @@ 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);
> @@ -2450,6 +2461,7 @@ 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);
>
> @@ -2511,6 +2523,7 @@ 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';
> @@ -2528,6 +2541,7 @@ 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);
>
--
Nicolas Ferre
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[PATCH v2 0/9] Various patches for SAMA5D2 backup mode Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
[PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
Re: [PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend Nicolas Ferre <nicolas.ferre@microchip.com> - 2017-09-19 12:20 +0200
Re: [PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend Richard Genoud <richard.genoud@gmail.com> - 2017-09-20 16:40 +0200
[PATCH v2 6/9] ehci-atmel: Power down during suspend is normal Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
Re: [PATCH v2 6/9] ehci-atmel: Power down during suspend is normal Nicolas Ferre <nicolas.ferre@microchip.com> - 2017-09-22 14:40 +0200
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Re: [PATCH v2 7/9] pwm: atmel-tcb: Support backup mode Nicolas Ferre <nicolas.ferre@microchip.com> - 2017-09-22 14:50 +0200
[PATCH v2 1/9] clk: at91: pmc: Wait for clocks when resuming Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
Re: [PATCH v2 1/9] clk: at91: pmc: Wait for clocks when resuming Ludovic Desroches <ludovic.desroches@microchip.com> - 2017-09-22 14:10 +0200
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[PATCH v2 5/9] mtd: nand: atmel: Report PMECC failures as errors Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
Re: [PATCH v2 5/9] mtd: nand: atmel: Report PMECC failures as errors Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-09-18 12:10 +0200
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Re: [PATCH v2 4/9] mtd: nand: atmel: Avoid ECC errors when leaving backup mode Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-09-18 12:00 +0200
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Re: [PATCH v2 8/9] atmel_flexcom: Support backup mode Nicolas Ferre <nicolas.ferre@microchip.com> - 2017-09-19 11:30 +0200
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[PATCH v2 3/9] clk: at91: pmc: Support backup for programmable clocks Romain Izard <romain.izard.pro@gmail.com> - 2017-09-15 16:10 +0200
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