[{"id":1766188,"web_url":"http://patchwork.ozlabs.org/comment/1766188/","msgid":"","list_archive_url":null,"date":"2017-09-11T09:52:12","subject":"Re: [PATCH v1 10/10] tty/serial: atmel: Prevent a warning on suspend","submitter":{"id":8236,"url":"http://patchwork.ozlabs.org/api/people/8236/","name":"Romain Izard","email":"romain.izard.pro@gmail.com"},"content":"2017-09-08 17:36 GMT+02:00 Romain Izard :\n> The atmel serial port driver reported the following warning on suspend:\n> atmel_usart f8020000.serial: ttyS1: Unable to drain transmitter\n>\n> As the ATMEL_US_TXEMPTY status bit in ATMEL_US_CSR is always cleared\n> when the transmitter is disabled, we need to know the transmitter's\n> state to return the real fifo state. And as ATMEL_US_CR is write-only,\n> it is necessary to save the state of the transmitter in a local\n> variable, and update the variable when TXEN and TXDIS is written in\n> ATMEL_US_CR.\n>\n> After those changes, atmel_tx_empty can return \"empty\" on suspend, the\n> warning in uart_suspend_port disappears, and suspending is 20ms shorter\n> for each enabled Atmel serial port.\n>\n> Signed-off-by: Romain Izard \n> ---\n> drivers/tty/serial/atmel_serial.c | 13 +++++++++++++\n> 1 file changed, 13 insertions(+)\n>\n> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c\n> index 7551cab438ff..195c0d1b594e 100644\n> --- a/drivers/tty/serial/atmel_serial.c\n> +++ b/drivers/tty/serial/atmel_serial.c\n> @@ -171,6 +171,7 @@ struct atmel_uart_port {\n> bool has_hw_timer;\n> struct timer_list uart_timer;\n>\n> + bool tx_stopped;\n> bool suspended;\n> unsigned int pending;\n> unsigned int pending_status;\n> @@ -380,6 +381,10 @@ static int atmel_config_rs485(struct uart_port *port,\n> */\n> static u_int atmel_tx_empty(struct uart_port *port)\n> {\n> + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);\n> +\n> + if (atmel_port->tx_stopped)\n> + return TIOCSER_TEMT;\n> return (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXEMPTY) ?\n> TIOCSER_TEMT :\n> 0;\n> @@ -485,6 +490,7 @@ static void atmel_stop_tx(struct uart_port *port)\n> * is fully transmitted.\n> */\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS);\n> + atmel_port->tx_stopped = true;\n>\n> /* Disable interrupts */\n> atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);\n> @@ -492,6 +498,7 @@ static void atmel_stop_tx(struct uart_port *port)\n> if ((port->rs485.flags & SER_RS485_ENABLED) &&\n> !(port->rs485.flags & SER_RS485_RX_DURING_TX))\n> atmel_start_rx(port);\n> +\n> }\n>\n> /*\n> @@ -521,6 +528,7 @@ static void atmel_start_tx(struct uart_port *port)\n>\n> /* re-enable the transmitter */\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);\n> + atmel_port->tx_stopped = false;\n> }\n>\n> /*\n> @@ -1866,6 +1874,7 @@ static int atmel_startup(struct uart_port *port)\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);\n> /* enable xmit & rcvr */\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);\n> + atmel_port->tx_stopped = false;\n>\n> setup_timer(&atmel_port->uart_timer,\n> atmel_uart_timer_callback,\n> @@ -2122,6 +2131,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,\n>\n> /* disable receiver and transmitter */\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXDIS);\n> + atmel_port->tx_stopped = true;\n>\n> /* mode */\n> if (port->rs485.flags & SER_RS485_ENABLED) {\n> @@ -2207,6 +2217,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,\n> atmel_uart_writel(port, ATMEL_US_BRGR, quot);\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);\n> + atmel_port->tx_stopped = false;\n>\n> /* restore interrupts */\n> atmel_uart_writel(port, ATMEL_US_IER, imr);\n> @@ -2450,6 +2461,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)\n>\n> /* Make sure that tx path is actually able to send characters */\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);\n> + atmel_port->tx_stopped = false;\n>\n> uart_console_write(port, s, count, atmel_console_putchar);\n>\n> @@ -2528,6 +2540,7 @@ static int __init atmel_console_setup(struct console *co, char *options)\n> atmel_uart_writel(port, ATMEL_US_IDR, -1);\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);\n> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);\n> + atmel_port->tx_stopped = false;\n>\n> if (options)\n> uart_parse_options(options, &baud, &parity, &bits, &flow);\n> --\n> 2.11.0\n>\n\nUnfortunately this patch was broken when I reported it from my branch to\nthe v4.13, as it does not build because of the missing declaration of\n'atmel_port' in 'atmel_console_setup'.\n\nI'll send a corrected version for v2.","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org; 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