From: Romain Izard <romain.izard.pro@gmail.com>
To: Nicolas Ferre <nicolas.ferre@microchip.com>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Boris Brezillon <boris.brezillon@free-electrons.com>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@codeaurora.org>,
Ludovic Desroches <ludovic.desroches@microchip.com>,
Wenyou Yang <wenyou.yang@atmel.com>,
Josh Wu <rainyfeeling@outlook.com>,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Marek Vasut <marek.vasut@gmail.com>,
Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>,
Thierry Reding <thierry.reding@gmail.com>,
Richard Genoud <richard.genoud@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Stern <stern@rowland.harvard.edu>
Cc: linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mtd@lists.infradead.org, linux-pwm@vger.kernel.org,
linux-serial@vger.kernel.org, linux-usb@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Romain Izard <romain.izard.pro@gmail.com>
Subject: [PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend
Date: Fri, 15 Sep 2017 16:04:11 +0200 [thread overview]
Message-ID: <20170915140411.31716-10-romain.izard.pro@gmail.com> (raw)
In-Reply-To: <20170915140411.31716-1-romain.izard.pro@gmail.com>
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>
---
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);
--
2.11.0
next prev parent reply other threads:[~2017-09-15 14:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-15 14:04 [PATCH v2 0/9] Various patches for SAMA5D2 backup mode Romain Izard
2017-09-15 14:04 ` [PATCH v2 1/9] clk: at91: pmc: Wait for clocks when resuming Romain Izard
2017-09-22 12:05 ` Ludovic Desroches
2017-09-22 12:13 ` Nicolas Ferre
2017-09-15 14:04 ` [PATCH v2 2/9] clk: at91: pmc: Save SCSR during suspend Romain Izard
2017-09-15 14:04 ` [PATCH v2 3/9] clk: at91: pmc: Support backup for programmable clocks Romain Izard
2017-09-22 10:31 ` Nicolas Ferre
2017-09-25 8:25 ` Romain Izard
2017-09-15 14:04 ` [PATCH v2 4/9] mtd: nand: atmel: Avoid ECC errors when leaving backup mode Romain Izard
2017-09-18 9:50 ` Boris Brezillon
2017-09-15 14:04 ` [PATCH v2 5/9] mtd: nand: atmel: Report PMECC failures as errors Romain Izard
2017-09-18 10:00 ` Boris Brezillon
2017-09-21 9:22 ` Romain Izard
2017-09-15 14:04 ` [PATCH v2 6/9] ehci-atmel: Power down during suspend is normal Romain Izard
2017-09-22 12:40 ` Nicolas Ferre
2017-09-15 14:04 ` [PATCH v2 7/9] pwm: atmel-tcb: Support backup mode Romain Izard
2017-09-22 12:42 ` Nicolas Ferre
2017-09-15 14:04 ` [PATCH v2 8/9] atmel_flexcom: " Romain Izard
2017-09-19 9:29 ` Nicolas Ferre
2017-09-19 15:25 ` Lee Jones
2017-09-20 8:30 ` Romain Izard
2017-09-20 9:18 ` Alexandre Belloni
2017-09-15 14:04 ` Romain Izard [this message]
2017-09-19 10:19 ` [PATCH v2 9/9] tty/serial: atmel: Prevent a warning on suspend Nicolas Ferre
2017-09-20 14:35 ` Richard Genoud
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170915140411.31716-10-romain.izard.pro@gmail.com \
--to=romain.izard.pro@gmail.com \
--cc=alexandre.belloni@free-electrons.com \
--cc=boris.brezillon@free-electrons.com \
--cc=computersforpeace@gmail.com \
--cc=cyrille.pitchen@wedev4u.fr \
--cc=dwmw2@infradead.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=ludovic.desroches@microchip.com \
--cc=marek.vasut@gmail.com \
--cc=mturquette@baylibre.com \
--cc=nicolas.ferre@microchip.com \
--cc=rainyfeeling@outlook.com \
--cc=richard.genoud@gmail.com \
--cc=sboyd@codeaurora.org \
--cc=stern@rowland.harvard.edu \
--cc=thierry.reding@gmail.com \
--cc=wenyou.yang@atmel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).