From: Benoit Goby <benoit@android.com>
Date: Wed, 20 Oct 2010 04:58:13 +0000 (-0700)
Subject: mdm6600: Force tty->low_latency to 1
X-Git-Tag: firefly_0821_release~9834^2~407
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ddc94c1701ab3ce0037547843cd338e33601b28b;p=firefly-linux-kernel-4.4.55.git

mdm6600: Force tty->low_latency to 1

This makes the tty push data immediately to the ldisc when
flip_buffer_push is called instead of scheduling a delayed
workqueue. This fixes the dropped data problem.

Change-Id: I9558e3b4529653983ec9bf8af8ae7c8f8c25787f
Signed-off-by: Benoit Goby <benoit@android.com>
---

diff --git a/drivers/usb/serial/mdm6600.c b/drivers/usb/serial/mdm6600.c
index 3c37fd36869c..5f00b3fbeed9 100644
--- a/drivers/usb/serial/mdm6600.c
+++ b/drivers/usb/serial/mdm6600.c
@@ -351,6 +351,9 @@ static int mdm6600_open(struct tty_struct *tty, struct usb_serial_port *port)
 
 	WARN_ON_ONCE(modem->port != port);
 
+	if (tty)
+		tty->low_latency = 1;
+
 	modem->tiocm_status = 0;
 
 	modem->opened = 1;
@@ -738,8 +741,8 @@ static void mdm6600_read_bulk_work(struct work_struct *work)
 		c = mdm6600_pass_to_tty(tty, u->transfer_buffer,
 			u->actual_length);
 		if (c != u->actual_length)
-			pr_warn("%s: dropped %u of %u bytes\n",
-				__func__, u->actual_length - c,
+			pr_warn("%s: port %d: dropped %u of %u bytes\n",
+				__func__, modem->number, u->actual_length - c,
 				u->actual_length);
 		tty_kref_put(tty);