[110/141] USB: io_ti: fix chars_in_buffer overhead

[Steven Rostedt]

3.6.11.6 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jhovold@xxxxxxxxx>

[ Upstream commit b16634adce951a7371be931487034f7365971ed0 ]

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 263e1f9f ("USB:
io_ti: 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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 drivers/usb/serial/io_ti.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index d2b6008..93cf729 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -2163,6 +2163,18 @@ static int edge_chars_in_buffer(struct tty_struct *tty)
 	return chars;
 }
 
+static bool edge_tx_empty(struct usb_serial_port *port)
+{
+	struct edgeport_port *edge_port = usb_get_serial_port_data(port);
+	int ret;
+
+	ret = tx_active(edge_port);
+	if (ret > 0)
+		return false;
+
+	return true;
+}
+
 static void edge_throttle(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
@@ -2739,6 +2751,7 @@ static struct usb_serial_driver edgeport_1port_device = {
 	.write			= edge_write,
 	.write_room		= edge_write_room,
 	.chars_in_buffer	= edge_chars_in_buffer,
+	.tx_empty		= edge_tx_empty,
 	.break_ctl		= edge_break,
 	.read_int_callback	= edge_interrupt_callback,
 	.read_bulk_callback	= edge_bulk_in_callback,
@@ -2770,6 +2783,7 @@ static struct usb_serial_driver edgeport_2port_device = {
 	.write			= edge_write,
 	.write_room		= edge_write_room,
 	.chars_in_buffer	= edge_chars_in_buffer,
+	.tx_empty		= edge_tx_empty,
 	.break_ctl		= edge_break,
 	.read_int_callback	= edge_interrupt_callback,
 	.read_bulk_callback	= edge_bulk_in_callback,
-- 
1.7.10.4


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