2013-08-01 16:49:17

by Vineet Gupta

Subject: [PATCH 1/2] serial/arc-uart: Handle Rx Error Interrupts w/o any data

Currently, Rx error handling only triggers if there is some Rx data.
Fix that by checking for error - before the data handling.

Reported-by: Mischa Jonker <[email protected]>
Tested-by: Mischa Jonker <[email protected]>
Signed-off-by: Vineet Gupta <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
drivers/tty/serial/arc_uart.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 22f280a..10f981b 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -209,9 +209,9 @@ static void arc_serial_start_tx(struct uart_port *port)
arc_serial_tx_chars(uart);
}

-static void arc_serial_rx_chars(struct arc_uart_port *uart)
+static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
{
- unsigned int status, ch, flg = 0;
+ unsigned int ch, flg = 0;

/*
* UART has 4 deep RX-FIFO. Driver's recongnition of this fact
@@ -222,11 +222,11 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)
* before RX-EMPTY=0, implies some sort of buffering going on in the
* controller, which is indeed the Rx-FIFO.
*/
- while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
-
- ch = UART_GET_DATA(uart);
- uart->port.icount.rx++;
-
+ do {
+ /*
+ * This could be an Rx Intr for err (no data),
+ * so check err and clear that Intr first
+ */
if (unlikely(status & (RXOERR | RXFERR))) {
if (status & RXOERR) {
uart->port.icount.overrun++;
@@ -242,6 +242,12 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)
} else
flg = TTY_NORMAL;

+ if (status & RXEMPTY)
+ continue;
+
+ ch = UART_GET_DATA(uart);
+ uart->port.icount.rx++;
+
if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
goto done;

@@ -249,7 +255,7 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)

done:
tty_flip_buffer_push(&uart->port.state->port);
- }
+ } while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
}

/*
@@ -292,11 +298,11 @@ static irqreturn_t arc_serial_isr(int irq, void *dev_id)
* notifications from the UART Controller.
* To demultiplex between the two, we check the relevant bits
*/
- if ((status & RXIENB) && !(status & RXEMPTY)) {
+ if (status & RXIENB) {

/* already in ISR, no need of xx_irqsave */
spin_lock(&uart->port.lock);
- arc_serial_rx_chars(uart);
+ arc_serial_rx_chars(uart, status);
spin_unlock(&uart->port.lock);
}

--
1.8.1.2

2013-08-01 16:50:12

by Vineet Gupta

Subject: [PATCH 2/2] serial/arc-uart: Remove the goto/label

Signed-off-by: Vineet Gupta <[email protected]>
Cc: Mischa Jonker <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
drivers/tty/serial/arc_uart.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 10f981b..c7aa313a 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -248,12 +248,9 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
ch = UART_GET_DATA(uart);
uart->port.icount.rx++;

- if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
- goto done;
+ if (!(uart_handle_sysrq_char(&uart->port, ch)))
+ uart_insert_char(&uart->port, status, RXOERR, ch, flg);

- uart_insert_char(&uart->port, status, RXOERR, ch, flg);
-
-done:
tty_flip_buffer_push(&uart->port.state->port);
} while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
}
--
1.8.1.2