Hi,
I recently found my system locking up under some conditions. I dug
through the code a bit and the result is this collections of various
changes. Some of it may not be required and has just been created out of
half-baked theories and re-reading the documentation. The actual failing
scenarios seem to be:
- RX IRQ conditions are handled while the receiver is disabled, leaving
the driver in an infinite loop
- console_put_char seems to be interrupted by uart_shutdown disabling
the transmitter while/just before printing
I.e. overall I tried to serialize all operations using the port lock to
avoid such interaction.
Sören
Sören Brinkmann (9):
tty: xuartps: Beautify read-modify writes
tty: xuartps: Use spinlock to serialize HW access
tty: xuartps: Always enable transmitter in start_tx
tty: xuartps: Clear interrupt status register in shutdown
tty: xuartps: Improve startup function
tty: xuartps: Keep lock for whole ISR
tty: xuartps: Acquire port lock for shutdown
tty: xuartps: Move RX path into helper function
tty: xuartps: Only handle RX IRQs when RX is enabled
drivers/tty/serial/xilinx_uartps.c | 129 ++++++++++++++++++++++---------------
1 file changed, 78 insertions(+), 51 deletions(-)
--
2.6.2.3.ga463a5b
Non-functional, formatting changes to ease reading the code.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 009e0dbc12d2..50d4082d2354 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -515,12 +515,14 @@ static void cdns_uart_start_tx(struct uart_port *port)
if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port))
return;
- status = readl(port->membase + CDNS_UART_CR_OFFSET);
- /* Set the TX enable bit and clear the TX disable bit to enable the
+ /*
+ * Set the TX enable bit and clear the TX disable bit to enable the
* transmitter.
*/
- writel((status & ~CDNS_UART_CR_TX_DIS) | CDNS_UART_CR_TX_EN,
- port->membase + CDNS_UART_CR_OFFSET);
+ status = readl(port->membase + CDNS_UART_CR_OFFSET);
+ status &= ~CDNS_UART_CR_TX_DIS;
+ status |= CDNS_UART_CR_TX_EN;
+ writel(status, port->membase + CDNS_UART_CR_OFFSET);
while (numbytes-- && ((readl(port->membase + CDNS_UART_SR_OFFSET) &
CDNS_UART_SR_TXFULL)) != CDNS_UART_SR_TXFULL) {
@@ -1123,8 +1125,9 @@ static void cdns_uart_console_write(struct console *co, const char *s,
* clear the TX disable bit to enable the transmitter.
*/
ctrl = readl(port->membase + CDNS_UART_CR_OFFSET);
- writel((ctrl & ~CDNS_UART_CR_TX_DIS) | CDNS_UART_CR_TX_EN,
- port->membase + CDNS_UART_CR_OFFSET);
+ ctrl &= ~CDNS_UART_CR_TX_DIS;
+ ctrl |= CDNS_UART_CR_TX_EN;
+ writel(ctrl, port->membase + CDNS_UART_CR_OFFSET);
uart_console_write(port, s, count, cdns_uart_console_putchar);
cdns_uart_console_wait_tx(port);
--
2.6.2.3.ga463a5b
Instead of disabling the IRQ, use the spin lock to serialize accesses to
the HW. This protects the driver from interference of non-IRQ callbacks
with each other and makes the driver more consistent in its
serialization method.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 50d4082d2354..dc1987f3dc0a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -947,10 +947,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
{
u32 imr;
int c;
+ unsigned long flags;
- /* Disable all interrupts */
- imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
- writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+ spin_lock_irqsave(&port->lock, flags);
/* Check if FIFO is empty */
if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
@@ -959,8 +958,7 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
c = (unsigned char) readl(
port->membase + CDNS_UART_FIFO_OFFSET);
- /* Enable interrupts */
- writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+ spin_unlock_irqrestore(&port->lock, flags);
return c;
}
@@ -968,10 +966,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
u32 imr;
+ unsigned long flags;
- /* Disable all interrupts */
- imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
- writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+ spin_lock_irqsave(&port->lock, flags);
/* Wait until FIFO is empty */
while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
@@ -986,8 +983,7 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
CDNS_UART_SR_TXEMPTY))
cpu_relax();
- /* Enable interrupts */
- writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+ spin_unlock_irqrestore(&port->lock, flags);
return;
}
--
2.6.2.3.ga463a5b
start_tx must start transmitting characters. Regardless of the state of
the circular buffer, always enable the transmitter hardware.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index dc1987f3dc0a..5edd1efca015 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -512,9 +512,6 @@ static void cdns_uart_start_tx(struct uart_port *port)
{
unsigned int status, numbytes = port->fifosize;
- if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port))
- return;
-
/*
* Set the TX enable bit and clear the TX disable bit to enable the
* transmitter.
@@ -524,6 +521,9 @@ static void cdns_uart_start_tx(struct uart_port *port)
status |= CDNS_UART_CR_TX_EN;
writel(status, port->membase + CDNS_UART_CR_OFFSET);
+ if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port))
+ return;
+
while (numbytes-- && ((readl(port->membase + CDNS_UART_SR_OFFSET) &
CDNS_UART_SR_TXFULL)) != CDNS_UART_SR_TXFULL) {
/* Break if no more data available in the UART buffer */
--
2.6.2.3.ga463a5b
When shutting down the UART, clear the interrupt status register.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 5edd1efca015..738df6bb2646 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -825,6 +825,7 @@ static void cdns_uart_shutdown(struct uart_port *port)
/* Disable interrupts */
status = readl(port->membase + CDNS_UART_IMR_OFFSET);
writel(status, port->membase + CDNS_UART_IDR_OFFSET);
+ writel(0xffffffff, port->membase + CDNS_UART_ISR_OFFSET);
/* Disable the TX and RX */
writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
--
2.6.2.3.ga463a5b
The startup function is supposed to initialize the UART for receiving.
Hence, don't enable the TX part. Also, protect HW accesses with the port
lock.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 738df6bb2646..b189e600d4ab 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -755,6 +755,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
*/
static int cdns_uart_startup(struct uart_port *port)
{
+ unsigned long flags;
unsigned int retval = 0, status = 0;
retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
@@ -762,6 +763,8 @@ static int cdns_uart_startup(struct uart_port *port)
if (retval)
return retval;
+ spin_lock_irqsave(&port->lock, flags);
+
/* Disable the TX and RX */
writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
port->membase + CDNS_UART_CR_OFFSET);
@@ -772,15 +775,14 @@ static int cdns_uart_startup(struct uart_port *port)
writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
port->membase + CDNS_UART_CR_OFFSET);
- status = readl(port->membase + CDNS_UART_CR_OFFSET);
-
- /* Clear the RX disable and TX disable bits and then set the TX enable
- * bit and RX enable bit to enable the transmitter and receiver.
+ /*
+ * Clear the RX disable bit and then set the RX enable bit to enable
+ * the receiver.
*/
- writel((status & ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS))
- | (CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN |
- CDNS_UART_CR_STOPBRK),
- port->membase + CDNS_UART_CR_OFFSET);
+ status = readl(port->membase + CDNS_UART_CR_OFFSET);
+ status &= CDNS_UART_CR_RX_DIS;
+ status |= CDNS_UART_CR_RX_EN;
+ writel(status, port->membase + CDNS_UART_CR_OFFSET);
/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
* no parity.
@@ -811,6 +813,8 @@ static int cdns_uart_startup(struct uart_port *port)
CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
port->membase + CDNS_UART_IER_OFFSET);
+ spin_unlock_irqrestore(&port->lock, flags);
+
return retval;
}
--
2.6.2.3.ga463a5b
The RX path in the interrupt handler released a lock unnecessarily.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index b189e600d4ab..544ea13e2e93 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -265,9 +265,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
data, status);
}
- spin_unlock(&port->lock);
tty_flip_buffer_push(&port->state->port);
- spin_lock(&port->lock);
}
/* Dispatch an appropriate handler */
--
2.6.2.3.ga463a5b
Shutting down the UART port can happen while console operations are in
progress. Holding the port lock serializes these operations and avoids
the UART HW to be disabled in the middle of console prints.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 544ea13e2e93..4904eec37621 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -823,6 +823,9 @@ static int cdns_uart_startup(struct uart_port *port)
static void cdns_uart_shutdown(struct uart_port *port)
{
int status;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
/* Disable interrupts */
status = readl(port->membase + CDNS_UART_IMR_OFFSET);
@@ -832,6 +835,9 @@ static void cdns_uart_shutdown(struct uart_port *port)
/* Disable the TX and RX */
writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
port->membase + CDNS_UART_CR_OFFSET);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+
free_irq(port->irq, port);
}
--
2.6.2.3.ga463a5b
Move RX-related IRQ handling into a helper function.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 50 +++++++++++++++++++++-----------------
1 file changed, 28 insertions(+), 22 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 4904eec37621..149868cc003c 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -172,28 +172,8 @@ struct cdns_uart {
#define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
clk_rate_change_nb);
-/**
- * cdns_uart_isr - Interrupt handler
- * @irq: Irq number
- * @dev_id: Id of the port
- *
- * Return: IRQHANDLED
- */
-static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
+static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
{
- struct uart_port *port = (struct uart_port *)dev_id;
- unsigned long flags;
- unsigned int isrstatus, numbytes;
- unsigned int data;
- char status = TTY_NORMAL;
-
- spin_lock_irqsave(&port->lock, flags);
-
- /* Read the interrupt status register to determine which
- * interrupt(s) is/are active.
- */
- isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
-
/*
* There is no hardware break detection, so we interpret framing
* error with all-zeros data as a break sequence. Most of the time,
@@ -223,6 +203,9 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
/* Receive Timeout Interrupt */
while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
CDNS_UART_SR_RXEMPTY)) {
+ u32 data;
+ char status = TTY_NORMAL;
+
data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
/* Non-NULL byte after BREAK is garbage (99%) */
@@ -263,10 +246,33 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
}
uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
- data, status);
+ data, status);
}
tty_flip_buffer_push(&port->state->port);
}
+}
+
+/**
+ * cdns_uart_isr - Interrupt handler
+ * @irq: Irq number
+ * @dev_id: Id of the port
+ *
+ * Return: IRQHANDLED
+ */
+static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
+{
+ struct uart_port *port = (struct uart_port *)dev_id;
+ unsigned long flags;
+ unsigned int isrstatus, numbytes;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ /* Read the interrupt status register to determine which
+ * interrupt(s) is/are active.
+ */
+ isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
+
+ cdns_uart_handle_rx(port, isrstatus);
/* Dispatch an appropriate handler */
if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
--
2.6.2.3.ga463a5b
Ignore RX-related interrupts if RX is not enabled.
Signed-off-by: Soren Brinkmann <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 149868cc003c..76a060a68934 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -161,6 +161,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
* @pclk: APB clock
* @baud: Current baud rate
* @clk_rate_change_nb: Notifier block for clock changes
+ * @flags: Driver flags
*/
struct cdns_uart {
struct uart_port *port;
@@ -168,7 +169,11 @@ struct cdns_uart {
struct clk *pclk;
unsigned int baud;
struct notifier_block clk_rate_change_nb;
+ u32 flags;
};
+
+#define CDNS_FLAG_RX_ENABLED BIT(0)
+
#define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
clk_rate_change_nb);
@@ -262,6 +267,7 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
{
struct uart_port *port = (struct uart_port *)dev_id;
+ struct cdns_uart *cdns_uart = port->private_data;
unsigned long flags;
unsigned int isrstatus, numbytes;
@@ -272,7 +278,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
*/
isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
- cdns_uart_handle_rx(port, isrstatus);
+ if (cdns_uart->flags & CDNS_FLAG_RX_ENABLED)
+ cdns_uart_handle_rx(port, isrstatus);
/* Dispatch an appropriate handler */
if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
@@ -576,11 +583,13 @@ static void cdns_uart_stop_tx(struct uart_port *port)
static void cdns_uart_stop_rx(struct uart_port *port)
{
unsigned int regval;
+ struct cdns_uart *cdns_uart = port->private_data;
regval = readl(port->membase + CDNS_UART_CR_OFFSET);
regval |= CDNS_UART_CR_RX_DIS;
/* Disable the receiver */
writel(regval, port->membase + CDNS_UART_CR_OFFSET);
+ cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED;
}
/**
@@ -761,6 +770,7 @@ static int cdns_uart_startup(struct uart_port *port)
{
unsigned long flags;
unsigned int retval = 0, status = 0;
+ struct cdns_uart *cdns_uart = port->private_data;
retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
(void *)port);
@@ -787,6 +797,7 @@ static int cdns_uart_startup(struct uart_port *port)
status &= CDNS_UART_CR_RX_DIS;
status |= CDNS_UART_CR_RX_EN;
writel(status, port->membase + CDNS_UART_CR_OFFSET);
+ cdns_uart->flags |= CDNS_FLAG_RX_ENABLED;
/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
* no parity.
@@ -830,6 +841,7 @@ static void cdns_uart_shutdown(struct uart_port *port)
{
int status;
unsigned long flags;
+ struct cdns_uart *cdns_uart = port->private_data;
spin_lock_irqsave(&port->lock, flags);
@@ -841,6 +853,7 @@ static void cdns_uart_shutdown(struct uart_port *port)
/* Disable the TX and RX */
writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
port->membase + CDNS_UART_CR_OFFSET);
+ cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED;
spin_unlock_irqrestore(&port->lock, flags);
--
2.6.2.3.ga463a5b
Hi Soren,
[auto build test WARNING on v4.3-rc7]
[also WARNING on: next-20151103]
url: https://github.com/0day-ci/linux/commits/Soren-Brinkmann/tty-xuartps-Beautify-read-modify-writes/20151104-082546
base: https://github.com/0day-ci/linux Soren-Brinkmann/tty-xuartps-Beautify-read-modify-writes/20151104-082546
config: i386-allmodconfig (attached as .config)
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
drivers/tty/serial/xilinx_uartps.c: In function 'cdns_uart_poll_get_char':
>> drivers/tty/serial/xilinx_uartps.c:948:6: warning: unused variable 'imr' [-Wunused-variable]
u32 imr;
^
drivers/tty/serial/xilinx_uartps.c: In function 'cdns_uart_poll_put_char':
drivers/tty/serial/xilinx_uartps.c:968:6: warning: unused variable 'imr' [-Wunused-variable]
u32 imr;
^
vim +/imr +948 drivers/tty/serial/xilinx_uartps.c
19038ad9f Lars-Peter Clausen 2014-11-05 932
19f22efdb Thomas Betker 2015-03-12 933 val = readl(port->membase + CDNS_UART_MODEMCR_OFFSET);
19038ad9f Lars-Peter Clausen 2014-11-05 934
19038ad9f Lars-Peter Clausen 2014-11-05 935 val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR);
19038ad9f Lars-Peter Clausen 2014-11-05 936
19038ad9f Lars-Peter Clausen 2014-11-05 937 if (mctrl & TIOCM_RTS)
19038ad9f Lars-Peter Clausen 2014-11-05 938 val |= CDNS_UART_MODEMCR_RTS;
19038ad9f Lars-Peter Clausen 2014-11-05 939 if (mctrl & TIOCM_DTR)
19038ad9f Lars-Peter Clausen 2014-11-05 940 val |= CDNS_UART_MODEMCR_DTR;
19038ad9f Lars-Peter Clausen 2014-11-05 941
19f22efdb Thomas Betker 2015-03-12 942 writel(val, port->membase + CDNS_UART_MODEMCR_OFFSET);
61ec90169 John Linn 2011-04-30 943 }
61ec90169 John Linn 2011-04-30 944
6ee04c6c5 Vlad Lungu 2013-10-17 945 #ifdef CONFIG_CONSOLE_POLL
d9bb3fb12 Soren Brinkmann 2014-04-04 946 static int cdns_uart_poll_get_char(struct uart_port *port)
6ee04c6c5 Vlad Lungu 2013-10-17 947 {
6ee04c6c5 Vlad Lungu 2013-10-17 @948 u32 imr;
6ee04c6c5 Vlad Lungu 2013-10-17 949 int c;
c2fd7b9d5 Soren Brinkmann 2015-11-03 950 unsigned long flags;
6ee04c6c5 Vlad Lungu 2013-10-17 951
c2fd7b9d5 Soren Brinkmann 2015-11-03 952 spin_lock_irqsave(&port->lock, flags);
6ee04c6c5 Vlad Lungu 2013-10-17 953
6ee04c6c5 Vlad Lungu 2013-10-17 954 /* Check if FIFO is empty */
19f22efdb Thomas Betker 2015-03-12 955 if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
6ee04c6c5 Vlad Lungu 2013-10-17 956 c = NO_POLL_CHAR;
:::::: The code at line 948 was first introduced by commit
:::::: 6ee04c6c5488b2b7fdfa22c771c127411f86e610 tty: xuartps: Add polled mode support for xuartps
:::::: TO: Vlad Lungu <[email protected]>
:::::: CC: Greg Kroah-Hartman <[email protected]>
---
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