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Subject[PATCH 04/11] Blackfin SPORT UART: fix overrun errors
Date
From: Cliff Cai <cliff.cai@analog.com>

Push the ty_flip_buffer_push() call from the IRQ handler to a timer so as
to improve performance and decrease likelihood of overruns.

URL: http://blackfin.uclinux.org/gf/tracker/3911
Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
---
drivers/serial/bfin_sport_uart.c | 31 ++++++++++++++++++++++++-------
1 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/serial/bfin_sport_uart.c b/drivers/serial/bfin_sport_uart.c
index 34b4ae0..fa80411 100644
--- a/drivers/serial/bfin_sport_uart.c
+++ b/drivers/serial/bfin_sport_uart.c
@@ -88,7 +88,8 @@ unsigned short bfin_uart_pin_req_sport1[] =
struct sport_uart_port {
struct uart_port port;
char *name;
-
+ struct timer_list rx_timer;
+ int once;
int tx_irq;
int rx_irq;
int err_irq;
@@ -116,9 +117,10 @@ static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
SPORT_PUT_TX(up, value);
}

-static inline unsigned int rx_one_byte(struct sport_uart_port *up)
+static inline unsigned char rx_one_byte(struct sport_uart_port *up)
{
- unsigned int value, extract;
+ unsigned int value;
+ unsigned char extract;
u32 tmp_mask1, tmp_mask2, tmp_shift, tmp;

value = SPORT_GET_RX32(up);
@@ -175,11 +177,19 @@ static int sport_uart_setup(struct sport_uart_port *up, int sclk, int baud_rate)
return 0;
}

+static void rx_push(unsigned long data)
+{
+ struct sport_uart_port *up = (struct sport_uart_port *)data;
+ struct tty_struct *tty = up->port.info->port.tty;
+ tty_flip_buffer_push(tty);
+ add_timer(&up->rx_timer);
+}
+
static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
{
struct sport_uart_port *up = dev_id;
struct tty_struct *tty = up->port.info->port.tty;
- unsigned int ch;
+ unsigned char ch;

do {
ch = rx_one_byte(up);
@@ -190,8 +200,10 @@ static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
else
tty_insert_flip_char(tty, ch, TTY_NORMAL);
} while (SPORT_GET_STAT(up) & RXNE);
- tty_flip_buffer_push(tty);
-
+ if (up->once == 0) {
+ add_timer(&up->rx_timer);
+ up->once = 1;
+ }
return IRQ_HANDLED;
}

@@ -257,7 +269,10 @@ static int sport_startup(struct uart_port *port)
printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
goto fail2;
}
-
+ init_timer(&up->rx_timer);
+ up->rx_timer.data = (unsigned long)up;
+ up->rx_timer.expires = jiffies + 5;
+ up->rx_timer.function = (void *)rx_push;
if (port->line) {
if (peripheral_request_list(bfin_uart_pin_req_sport1, DRV_NAME))
goto fail3;
@@ -384,6 +399,8 @@ static void sport_stop_rx(struct uart_port *port)
{
struct sport_uart_port *up = (struct sport_uart_port *)port;

+ del_timer(&up->rx_timer);
+ up->once = 0;
pr_debug("%s enter\n", __func__);
/* Disable sport to stop rx */
SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
--
1.6.3.1


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