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

From: Ricardo Ribalda
Date: Thu Nov 18 2021 - 17:09:34 EST


Move the addition to the buffer into its own function and remove the
stream dependency to all the clock functions.

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
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 22b2bab0af5d9..d18bafd824a5d 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -459,18 +459,29 @@ 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:
@@ -523,20 +534,19 @@ 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
* the USB frame number to keep their own frame counters as long as they
@@ -558,46 +568,29 @@ 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;

@@ -606,15 +599,15 @@ 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;
}

/*
@@ -2057,7 +2050,7 @@ 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;
@@ -2186,7 +2179,7 @@ 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;

@@ -2204,7 +2197,7 @@ 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;
}
@@ -2231,5 +2224,5 @@ 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);
}
--
2.34.0.rc2.393.gf8c9666880-goog