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Subject[PATCH 6/7] USB: ti_usb_3410_5052: fix chars_in_buffer overhead
Date
Use the new generic usb-serial wait_until_sent implementation to wait
for hardware buffers to drain.

This removes the need to check the hardware buffers in chars_in_buffer
and thus removes the overhead introduced by commit 2c992cd73 ("USB:
ti_usb_3410_5052: query hardware-buffer status in chars_in_buffer")
without breaking tty_wait_until_sent (used by, for example, tcdrain,
tcsendbreak and close).

Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
drivers/usb/serial/ti_usb_3410_5052.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index cac47ae..c92c5ed 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -101,6 +101,7 @@ static int ti_write(struct tty_struct *tty, struct usb_serial_port *port,
const unsigned char *data, int count);
static int ti_write_room(struct tty_struct *tty);
static int ti_chars_in_buffer(struct tty_struct *tty);
+static bool ti_tx_empty(struct usb_serial_port *port);
static void ti_throttle(struct tty_struct *tty);
static void ti_unthrottle(struct tty_struct *tty);
static int ti_ioctl(struct tty_struct *tty,
@@ -222,6 +223,7 @@ static struct usb_serial_driver ti_1port_device = {
.write = ti_write,
.write_room = ti_write_room,
.chars_in_buffer = ti_chars_in_buffer,
+ .tx_empty = ti_tx_empty,
.throttle = ti_throttle,
.unthrottle = ti_unthrottle,
.ioctl = ti_ioctl,
@@ -253,6 +255,7 @@ static struct usb_serial_driver ti_2port_device = {
.write = ti_write,
.write_room = ti_write_room,
.chars_in_buffer = ti_chars_in_buffer,
+ .tx_empty = ti_tx_empty,
.throttle = ti_throttle,
.unthrottle = ti_unthrottle,
.ioctl = ti_ioctl,
@@ -684,8 +687,6 @@ static int ti_chars_in_buffer(struct tty_struct *tty)
struct ti_port *tport = usb_get_serial_port_data(port);
int chars = 0;
unsigned long flags;
- int ret;
- u8 lsr;

if (tport == NULL)
return 0;
@@ -694,16 +695,22 @@ static int ti_chars_in_buffer(struct tty_struct *tty)
chars = kfifo_len(&tport->write_fifo);
spin_unlock_irqrestore(&tport->tp_lock, flags);

- if (!chars) {
- ret = ti_get_lsr(tport, &lsr);
- if (!ret && !(lsr & TI_LSR_TX_EMPTY))
- chars = 1;
- }
-
dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
return chars;
}

+static bool ti_tx_empty(struct usb_serial_port *port)
+{
+ struct ti_port *tport = usb_get_serial_port_data(port);
+ int ret;
+ u8 lsr;
+
+ ret = ti_get_lsr(tport, &lsr);
+ if (!ret && !(lsr & TI_LSR_TX_EMPTY))
+ return false;
+
+ return true;
+}

static void ti_throttle(struct tty_struct *tty)
{
--
1.8.2.1


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