From 5d0fd3c806b9e932010931ae67dbb482020e0882 Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Mon, 27 Jul 2015 11:06:48 -0300
Subject: [media] uvcvideo: Disable hardware timestamps by default

The hardware timestamping implementation has been reported as not
working correctly on at least the Logitech C920. Until this can be
fixed, disable it by default.

Reported-by: Peter Rabbitson <rabbit@rabbit.us>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 4b5b3e8..d11fd6a 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -32,6 +32,7 @@
 #define DRIVER_DESC		"USB Video Class driver"
 
 unsigned int uvc_clock_param = CLOCK_MONOTONIC;
+unsigned int uvc_hw_timestamps_param;
 unsigned int uvc_no_drop_param;
 static unsigned int uvc_quirks_param = -1;
 unsigned int uvc_trace_param;
@@ -2078,6 +2079,8 @@ static int uvc_clock_param_set(const char *val, struct kernel_param *kp)
 module_param_call(clock, uvc_clock_param_set, uvc_clock_param_get,
 		  &uvc_clock_param, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(clock, "Video buffers timestamp clock");
+module_param_named(hwtimestamps, uvc_hw_timestamps_param, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(hwtimestamps, "Use hardware timestamps");
 module_param_named(nodrop, uvc_no_drop_param, uint, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(nodrop, "Don't drop incomplete frames");
 module_param_named(quirks, uvc_quirks_param, uint, S_IRUGO|S_IWUSR);
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index f839654..1c4a117 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -623,6 +623,9 @@ void uvc_video_clock_update(struct uvc_streaming *stream,
 	u32 rem;
 	u64 y;
 
+	if (!uvc_hw_timestamps_param)
+		return;
+
 	spin_lock_irqsave(&clock->lock, flags);
 
 	if (clock->count < clock->size)
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 816dd1a..1374bd9 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -593,6 +593,7 @@ extern unsigned int uvc_clock_param;
 extern unsigned int uvc_no_drop_param;
 extern unsigned int uvc_trace_param;
 extern unsigned int uvc_timeout_param;
+extern unsigned int uvc_hw_timestamps_param;
 
 #define uvc_trace(flag, msg...) \
 	do { \
-- 
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