[v2,7/8] media: uvcvideo: Refactor clock circular buffer

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 7c6448c6d706..c81a8362d582 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -464,18 +464,29 @@  static inline ktime_t uvc_video_get_time(void)
 		return ktime_get_real();
 }
 
+static void uvc_video_clock_add_sample(struct uvc_clock *clock,
+				       const struct uvc_clock_sample *sample)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&clock->lock, flags);
+
+	memcpy(&clock->samples[clock->head], sample, sizeof(*sample));
+	clock->last_sof = sample->dev_sof;
+	clock->head = (clock->head + 1) % clock->size;
+	clock->count = min(clock->count + 1, clock->size);
+
+	spin_unlock_irqrestore(&clock->lock, flags);
+}
+
 static void
 uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 		       const u8 *data, int len)
 {
-	struct uvc_clock_sample *sample;
+	struct uvc_clock_sample sample;
 	unsigned int header_size;
 	bool has_pts = false;
 	bool has_scr = false;
-	unsigned long flags;
-	ktime_t time;
-	u16 host_sof;
-	u16 dev_sof;
 
 	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 	case UVC_STREAM_PTS | UVC_STREAM_SCR:
@@ -530,20 +541,19 @@  uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * only the first one will match the host_sof.
 	 */
 	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
-		dev_sof = usb_get_current_frame_number(stream->dev->udev);
+		sample.dev_sof =
+			usb_get_current_frame_number(stream->dev->udev);
 	else
-		dev_sof = get_unaligned_le16(&data[header_size - 2]);
+		sample.dev_sof = get_unaligned_le16(&data[header_size - 2]);
 
-	if (dev_sof == stream->clock.last_sof)
+	if (sample.dev_sof == stream->clock.last_sof)
 		return;
 
-	stream->clock.last_sof = dev_sof;
-
 	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
-		host_sof = dev_sof;
+		sample.host_sof = sample.dev_sof;
 	else
-		host_sof = usb_get_current_frame_number(stream->dev->udev);
-	time = uvc_video_get_time();
+		sample.host_sof = usb_get_current_frame_number(stream->dev->udev);
+	sample.host_time = uvc_video_get_time();
 
 	/*
 	 * The UVC specification allows device implementations that can't obtain
@@ -566,46 +576,29 @@  uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * the 8 LSBs of the delta are kept.
 	 */
 	if (stream->clock.sof_offset == (u16)-1) {
-		u16 delta_sof = (host_sof - dev_sof) & 255;
+		u16 delta_sof = (sample.host_sof - sample.dev_sof) & 255;
 		if (delta_sof >= 10)
 			stream->clock.sof_offset = delta_sof;
 		else
 			stream->clock.sof_offset = 0;
 	}
 
-	dev_sof = (dev_sof + stream->clock.sof_offset) & 2047;
-
-	spin_lock_irqsave(&stream->clock.lock, flags);
-
-	sample = &stream->clock.samples[stream->clock.head];
-	sample->dev_stc = get_unaligned_le32(&data[header_size - 6]);
-	sample->dev_sof = dev_sof;
-	sample->host_sof = host_sof;
-	sample->host_time = time;
-
-	/* Update the sliding window head and count. */
-	stream->clock.head = (stream->clock.head + 1) % stream->clock.size;
+	sample.dev_sof = (sample.dev_sof + stream->clock.sof_offset) & 2047;
+	sample.dev_stc = get_unaligned_le32(&data[header_size - 6]);
 
-	if (stream->clock.count < stream->clock.size)
-		stream->clock.count++;
-
-	spin_unlock_irqrestore(&stream->clock.lock, flags);
+	uvc_video_clock_add_sample(&stream->clock, &sample);
 }
 
-static void uvc_video_clock_reset(struct uvc_streaming *stream)
+static void uvc_video_clock_reset(struct uvc_clock *clock)
 {
-	struct uvc_clock *clock = &stream->clock;
-
 	clock->head = 0;
 	clock->count = 0;
 	clock->last_sof = -1;
 	clock->sof_offset = -1;
 }
 
-static int uvc_video_clock_init(struct uvc_streaming *stream)
+static int uvc_video_clock_init(struct uvc_clock *clock)
 {
-	struct uvc_clock *clock = &stream->clock;
-
 	spin_lock_init(&clock->lock);
 	clock->size = 32;
 
@@ -614,15 +607,15 @@  static int uvc_video_clock_init(struct uvc_streaming *stream)
 	if (clock->samples == NULL)
 		return -ENOMEM;
 
-	uvc_video_clock_reset(stream);
+	uvc_video_clock_reset(clock);
 
 	return 0;
 }
 
-static void uvc_video_clock_cleanup(struct uvc_streaming *stream)
+static void uvc_video_clock_cleanup(struct uvc_clock *clock)
 {
-	kfree(stream->clock.samples);
-	stream->clock.samples = NULL;
+	kfree(clock->samples);
+	clock->samples = NULL;
 }
 
 /*
@@ -2085,7 +2078,7 @@  int uvc_video_resume(struct uvc_streaming *stream, int reset)
 
 	stream->frozen = 0;
 
-	uvc_video_clock_reset(stream);
+	uvc_video_clock_reset(&stream->clock);
 
 	if (!uvc_queue_streaming(&stream->queue))
 		return 0;
@@ -2219,7 +2212,7 @@  int uvc_video_start_streaming(struct uvc_streaming *stream)
 {
 	int ret;
 
-	ret = uvc_video_clock_init(stream);
+	ret = uvc_video_clock_init(&stream->clock);
 	if (ret < 0)
 		return ret;
 
@@ -2237,7 +2230,7 @@  int uvc_video_start_streaming(struct uvc_streaming *stream)
 error_video:
 	usb_set_interface(stream->dev->udev, stream->intfnum, 0);
 error_commit:
-	uvc_video_clock_cleanup(stream);
+	uvc_video_clock_cleanup(&stream->clock);
 
 	return ret;
 }
@@ -2265,5 +2258,5 @@  void uvc_video_stop_streaming(struct uvc_streaming *stream)
 		usb_clear_halt(stream->dev->udev, pipe);
 	}
 
-	uvc_video_clock_cleanup(stream);
+	uvc_video_clock_cleanup(&stream->clock);
 }