On 4/17/25 4:00 AM, Kirill A. Korinsky wrote:
> Markus, Ian,
>
> here a future improvment of this diff, this time I stricly requires that
> mmap buffer is switched or "grab" only for the first sample of the frame.
>
> I can't reproduce glitches on my motion test case. May I ask you to try this
> one?
This one also works fine for me with motion, video(1), and luvcview.
>
> Index: sys/dev/usb/uvideo.c
> ===================================================================
> RCS file: /home/cvs/src/sys/dev/usb/uvideo.c,v
> diff -u -p -r1.257 uvideo.c
> --- sys/dev/usb/uvideo.c	6 Apr 2025 09:46:30 -0000	1.257
> +++ sys/dev/usb/uvideo.c	17 Apr 2025 08:00:03 -0000
> @@ -66,6 +66,7 @@ struct uvideo_softc {
>   	struct uvideo_frame_buffer		 sc_frame_buffer;
>   
>   	struct uvideo_mmap			 sc_mmap[UVIDEO_MAX_BUFFERS];
> +	struct uvideo_mmap			*sc_mmap_cur;
>   	uint8_t					*sc_mmap_buffer;
>   	size_t					 sc_mmap_buffer_size;
>   	int					 sc_mmap_buffer_idx;
> @@ -170,8 +171,8 @@ void		uvideo_vs_decode_stream_header(str
>   		    uint8_t *, int);
>   void		uvideo_vs_decode_stream_header_isight(struct uvideo_softc *,
>   		    uint8_t *, int);
> -int		uvideo_get_buf(struct uvideo_softc *);
> -void		uvideo_mmap_queue(struct uvideo_softc *, uint8_t *, int, int);
> +uint8_t *	uvideo_mmap_getbuf(struct uvideo_softc *);
> +void		uvideo_mmap_queue(struct uvideo_softc *, int, int);
>   void		uvideo_read(struct uvideo_softc *, uint8_t *, int);
>   usbd_status	uvideo_usb_control(struct uvideo_softc *, uint8_t, uint8_t,
>   		    uint16_t, uint8_t *, size_t);
> @@ -2333,6 +2334,7 @@ uvideo_vs_decode_stream_header(struct uv
>   	struct uvideo_frame_buffer *fb = &sc->sc_frame_buffer;
>   	struct usb_video_stream_header *sh;
>   	int sample_len;
> +	uint8_t *buf;
>   
>   	if (frame_size < UVIDEO_SH_MIN_LEN)
>   		/* frame too small to contain a valid stream header */
> @@ -2364,16 +2366,17 @@ uvideo_vs_decode_stream_header(struct uv
>   		fb->fid = sh->bFlags & UVIDEO_SH_FLAG_FID;
>   		fb->offset = 0;
>   		fb->error = 0;
> +	} else if (fb->fid != (sh->bFlags & UVIDEO_SH_FLAG_FID)) {
> +		/* first sample for a frame, due to flip FID */
> +		DPRINTF(1, "%s: %s: wrong FID, ignore last frame!\n",
> +		    DEVNAME(sc), __func__);
> +		fb->sample = 1;
> +		fb->fid = sh->bFlags & UVIDEO_SH_FLAG_FID;
> +		fb->offset = 0;
> +		fb->error = 0;
>   	} else {
> -		/* continues sample for a frame, check consistency */
> -		if (fb->fid != (sh->bFlags & UVIDEO_SH_FLAG_FID)) {
> -			DPRINTF(1, "%s: %s: wrong FID, ignore last frame!\n",
> -			    DEVNAME(sc), __func__);
> -			fb->sample = 1;
> -			fb->fid = sh->bFlags & UVIDEO_SH_FLAG_FID;
> -			fb->offset = 0;
> -			fb->error = 0;
> -		}
> +		/* continues sample for a frame */
> +		fb->sample++;
>   	}
>   
>   	if (sh->bFlags & UVIDEO_SH_FLAG_ERR) {
> @@ -2382,6 +2385,11 @@ uvideo_vs_decode_stream_header(struct uv
>   		fb->error = 1;
>   	}
>   
> +	if (sc->sc_mmap_flag)
> +		buf = uvideo_mmap_getbuf(sc);
> +	else
> +		buf = sc->sc_frame_buffer.buf;
> +
>   	/* save sample */
>   	sample_len = frame_size - sh->bLength;
>   	if (sample_len > fb->buf_size - fb->offset) {
> @@ -2390,8 +2398,8 @@ uvideo_vs_decode_stream_header(struct uv
>   		sample_len = fb->buf_size - fb->offset;
>   		fb->error = 1;
>   	}
> -	if (sample_len > 0) {
> -		bcopy(frame + sh->bLength, fb->buf + fb->offset, sample_len);
> +	if (buf && sample_len > 0) {
> +		bcopy(frame + sh->bLength, buf + fb->offset, sample_len);
>   		fb->offset += sample_len;
>   	}
>   
> @@ -2409,7 +2417,7 @@ uvideo_vs_decode_stream_header(struct uv
>   
>   		if (sc->sc_mmap_flag) {
>   			/* mmap */
> -			uvideo_mmap_queue(sc, fb->buf, fb->offset, fb->error);
> +			uvideo_mmap_queue(sc, fb->offset, fb->error);
>   		} else if (fb->error) {
>   			DPRINTF(1, "%s: %s: error frame, skipped!\n",
>   			    DEVNAME(sc), __func__);
> @@ -2446,6 +2454,7 @@ uvideo_vs_decode_stream_header_isight(st
>   {
>   	struct uvideo_frame_buffer *fb = &sc->sc_frame_buffer;
>   	int sample_len, header = 0;
> +	uint8_t *buf;
>   	uint8_t magic[] = {
>   	    0x11, 0x22, 0x33, 0x44,
>   	    0xde, 0xad, 0xbe, 0xef, 0xde, 0xad, 0xfa, 0xce };
> @@ -2463,27 +2472,52 @@ uvideo_vs_decode_stream_header_isight(st
>   	if (header) {
>   		if (sc->sc_mmap_flag) {
>   			/* mmap */
> -			uvideo_mmap_queue(sc, fb->buf, fb->offset, 0);
> +			uvideo_mmap_queue(sc, fb->offset, 0);
>   		} else {
>   			/* read */
>   			uvideo_read(sc, fb->buf, fb->offset);
>   		}
>   		fb->offset = 0;
>   	} else {
> +		if (sc->sc_mmap_flag)
> +			buf = uvideo_mmap_getbuf(sc);
> +		else
> +			buf = sc->sc_frame_buffer.buf;
> +
> +		if (buf == NULL)
> +			return;
> +
>   		/* save sample */
>   		sample_len = frame_size;
>   		if ((fb->offset + sample_len) <= fb->buf_size) {
> -			bcopy(frame, fb->buf + fb->offset, sample_len);
> +			bcopy(frame, buf + fb->offset, sample_len);
>   			fb->offset += sample_len;
>   		}
>   	}
>   }
>   
> -int
> -uvideo_get_buf(struct uvideo_softc *sc)
> +uint8_t *
> +uvideo_mmap_getbuf(struct uvideo_softc *sc)
>   {
>   	int i, idx = sc->sc_mmap_buffer_idx;
>   
> +	/*
> +	 * Section 2.4.3.2 explicitly allows multiple frames per one
> +	 * transfer and multiple transfers per one frame.
> +	 */
> +	if (sc->sc_mmap_cur != NULL)
> +		return sc->sc_mmap_cur->buf;
> +
> +	/* use the next buffer only for the first frame's sample */
> +	if (sc->sc_frame_buffer.sample > 1) {
> +		DPRINTF(1, "%s: %s: not the first sample: %d\n",
> +		    DEVNAME(sc), __func__, sc->sc_frame_buffer.sample);
> +		return NULL;
> +	}
> +
> +	if (sc->sc_mmap_count == 0 || sc->sc_mmap_buffer == NULL)
> +		panic("%s: mmap buffers not allocated", __func__);
> +
>   	/* find a buffer which is ready for queueing */
>   	for (i = 0; i < sc->sc_mmap_count; i++) {
>   		if (sc->sc_mmap[sc->sc_mmap_buffer_idx].v4l2_buf.flags &
> @@ -2497,51 +2531,45 @@ uvideo_get_buf(struct uvideo_softc *sc)
>   			sc->sc_mmap_buffer_idx = 0;
>   	}
>   
> -	if (i == sc->sc_mmap_count)
> -		return -1;
> +	if (i == sc->sc_mmap_count) {
> +		DPRINTF(1, "%s: %s: mmap queue is full!\n",
> +		    DEVNAME(sc), __func__);
> +		return NULL;
> +	}
> +
> +	sc->sc_mmap_cur = &sc->sc_mmap[idx];
>   
> -	return idx;
> +	return sc->sc_mmap_cur->buf;
>   }
>   
>   void
> -uvideo_mmap_queue(struct uvideo_softc *sc, uint8_t *buf, int len, int err)
> +uvideo_mmap_queue(struct uvideo_softc *sc, int len, int err)
>   {
> -	int i;
> -
> -	if (sc->sc_mmap_count == 0 || sc->sc_mmap_buffer == NULL)
> -		panic("%s: mmap buffers not allocated", __func__);
> -
> -	/* find a buffer which is ready for queueing */
> -	i = uvideo_get_buf(sc);
> -	if (i == -1) {
> -		DPRINTF(1, "%s: %s: mmap queue is full!\n",
> -		    DEVNAME(sc), __func__);
> +	if (sc->sc_mmap_cur == NULL)
>   		return;
> -	}
>   
> -	/* copy frame to mmap buffer and report length */
> -	bcopy(buf, sc->sc_mmap[i].buf, len);
> -	sc->sc_mmap[i].v4l2_buf.bytesused = len;
> +	/* report frame length */
> +	sc->sc_mmap_cur->v4l2_buf.bytesused = len;
>   
>   	/* timestamp it */
> -	getmicrouptime(&sc->sc_mmap[i].v4l2_buf.timestamp);
> -	sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMESTAMP_MASK;
> -	sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> -	sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
> -	sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
> -	sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMECODE;
> +	getmicrouptime(&sc->sc_mmap_cur->v4l2_buf.timestamp);
> +	sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMESTAMP_MASK;
> +	sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
> +	sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
> +	sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMECODE;
>   
>   	/* forward error bit */
> -	sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_ERROR;
> +	sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_ERROR;
>   	if (err)
> -		sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_ERROR;
> +		sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_ERROR;
>   
>   	/* queue it */
> -	sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_DONE;
> -	sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_QUEUED;
> -	SIMPLEQ_INSERT_TAIL(&sc->sc_mmap_q, &sc->sc_mmap[i], q_frames);
> -	DPRINTF(2, "%s: %s: frame queued on index %d\n",
> -	    DEVNAME(sc), __func__, i);
> +	sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_DONE;
> +	sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_QUEUED;
> +	SIMPLEQ_INSERT_TAIL(&sc->sc_mmap_q, sc->sc_mmap_cur, q_frames);
> +	sc->sc_mmap_cur = NULL;
> +	DPRINTF(2, "%s: %s: frame queued\n", DEVNAME(sc), __func__);
>   
>   	wakeup(sc);
>   
> @@ -3507,6 +3535,7 @@ uvideo_reqbufs(void *v, struct v4l2_requ
>   	}
>   
>   	sc->sc_mmap_buffer_idx = 0;
> +	sc->sc_mmap_cur = NULL;
>   
>   	/* tell how many buffers we have really allocated */
>   	rb->count = sc->sc_mmap_count;
>