[PATCH v3 7/8] media: uvcvideo: Refactor clock circular buffer

From: Ricardo Ribalda <ribalda@chromium.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-kernel@vger.kernel.org, "hn.chen" <hn.chen@sunplusit.com>,
	Ricardo Ribalda <ribalda@chromium.org>,
	linux-media@vger.kernel.org
Subject: [PATCH v3 7/8] media: uvcvideo: Refactor clock circular buffer
Date: Wed, 04 Jan 2023 11:45:25 +0100	[thread overview]
Message-ID: <20220920-resend-hwtimestamp-v3-7-db9faee7f47d@chromium.org> (raw)
In-Reply-To: <20220920-resend-hwtimestamp-v3-0-db9faee7f47d@chromium.org>

Isolate all the changes related to the clock circular buffer to its own
function, that way we can make changes easier to the buffer logic.

Also simplify the lock, by removing the circular buffer clock handling
from uvc_video_clock_decode().

And now that we are at it, unify the API of the clock functions.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 81 ++++++++++++++++++---------------------
 1 file changed, 37 insertions(+), 44 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 5c37b080e0c6..2c6da49ff84b 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:
@@ -531,20 +542,19 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * case 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
@@ -567,46 +577,29 @@ 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;
 
@@ -615,15 +608,15 @@ 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;
 }
 
 /*
@@ -2092,7 +2085,7 @@ 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;
@@ -2226,7 +2219,7 @@ 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;
 
@@ -2244,7 +2237,7 @@ 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;
 }
@@ -2272,5 +2265,5 @@ 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);
 }

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae
