V4L/DVB (7540): em28xx: convert to use videobuf-vmalloc

The usage of videobuf-vmalloc allows to cleanup em28xx logic.

Also, it reduced its size by about 5.42% on i386 arch (and about 7.5% on x86_64):

  39113    4876      40   44029    abfd old/em28xx.ko
  36731    4868      40   41639    a2a7 /home/v4l/master/v4l/em28xx.ko

Also, the preliminary tests, made on a single core 1.5 MHz Centrino showed
that CPU usage reduced from 42%-75% to 28%-33% (reports from "top") command.

A test with time command presented an even better result:

This is the performance tests I did, running code_example to get 1,000 frames
@29.995 Hz (about 35 seconds of stream), tested on a i386 machine, running at
1,5GHz:

	The old driver:

$ time -f "%E: %Us User time, %Ss Kernel time, %P CPU used" ./capture_example
0:34.21: 8.22s User time, 25.16s Kernel time, 97% CPU used

	The videobuf-based driver:

$ time -f "%E: %Us User time, %Ss Kernel time, %P CPU used" ./capture_example
0:35.36: 0.01s User time, 0.05s Kernel time, 0% CPU used

	Conclusion:

The time consumption to receive the stream where reduced from about 33.38
seconds to 0.05 seconds.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

3 files changed, 811 insertions, 898 deletions

diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
index 9aa96f1713a..95bc18d0e78 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -49,87 +49,10 @@ MODULE_PARM_DESC(reg_debug,"enable debug messages [URB reg]");
 		printk(KERN_INFO "%s %s :"fmt, \
 			 dev->name, __func__ , ##arg); } while (0)
 
-static unsigned int isoc_debug;
-module_param(isoc_debug,int,0644);
-MODULE_PARM_DESC(isoc_debug,"enable debug messages [isoc transfers]");
-
-#define em28xx_isocdbg(fmt, arg...) do {\
-	if (isoc_debug) \
-		printk(KERN_INFO "%s %s :"fmt, \
-			 dev->name, __func__ , ##arg); } while (0)
-
 static int alt = EM28XX_PINOUT;
 module_param(alt, int, 0644);
 MODULE_PARM_DESC(alt, "alternate setting to use for video endpoint");
 
-
-/*
- * em28xx_request_buffers()
- * allocate a number of buffers
- */
-u32 em28xx_request_buffers(struct em28xx *dev, u32 count)
-{
-	const size_t imagesize = PAGE_ALIGN(dev->frame_size);	/*needs to be page aligned cause the buffers can be mapped individually! */
-	void *buff = NULL;
-	u32 i;
-	em28xx_coredbg("requested %i buffers with size %zi\n",
-			count, imagesize);
-	if (count > EM28XX_NUM_FRAMES)
-		count = EM28XX_NUM_FRAMES;
-
-	dev->num_frames = count;
-	while (dev->num_frames > 0) {
-		if ((buff = vmalloc_32(dev->num_frames * imagesize))) {
-			memset(buff, 0, dev->num_frames * imagesize);
-			break;
-		}
-		dev->num_frames--;
-	}
-
-	for (i = 0; i < dev->num_frames; i++) {
-		dev->frame[i].bufmem = buff + i * imagesize;
-		dev->frame[i].buf.index = i;
-		dev->frame[i].buf.m.offset = i * imagesize;
-		dev->frame[i].buf.length = dev->frame_size;
-		dev->frame[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-		dev->frame[i].buf.sequence = 0;
-		dev->frame[i].buf.field = V4L2_FIELD_NONE;
-		dev->frame[i].buf.memory = V4L2_MEMORY_MMAP;
-		dev->frame[i].buf.flags = 0;
-	}
-	return dev->num_frames;
-}
-
-/*
- * em28xx_queue_unusedframes()
- * add all frames that are not currently in use to the inbuffer queue
- */
-void em28xx_queue_unusedframes(struct em28xx *dev)
-{
-	unsigned long lock_flags;
-	u32 i;
-
-	for (i = 0; i < dev->num_frames; i++)
-		if (dev->frame[i].state == F_UNUSED) {
-			dev->frame[i].state = F_QUEUED;
-			spin_lock_irqsave(&dev->queue_lock, lock_flags);
-			list_add_tail(&dev->frame[i].frame, &dev->inqueue);
-			spin_unlock_irqrestore(&dev->queue_lock, lock_flags);
-		}
-}
-
-/*
- * em28xx_release_buffers()
- * free frame buffers
- */
-void em28xx_release_buffers(struct em28xx *dev)
-{
-	if (dev->num_frames) {
-		vfree(dev->frame[0].bufmem);
-		dev->num_frames = 0;
-	}
-}
-
 /*
  * em28xx_read_reg_req()
  * reads data from the usb device specifying bRequest
@@ -469,346 +392,6 @@ int em28xx_resolution_set(struct em28xx *dev)
 	return em28xx_scaler_set(dev, dev->hscale, dev->vscale);
 }
 
-
-/******************* isoc transfer handling ****************************/
-
-#ifdef ENABLE_DEBUG_ISOC_FRAMES
-static void em28xx_isoc_dump(struct urb *urb)
-{
-	int len = 0;
-	int ntrans = 0;
-	int i;
-
-	printk(KERN_DEBUG "isocIrq: sf=%d np=%d ec=%x\n",
-	       urb->start_frame, urb->number_of_packets,
-	       urb->error_count);
-	for (i = 0; i < urb->number_of_packets; i++) {
-		unsigned char *buf =
-				urb->transfer_buffer +
-				urb->iso_frame_desc[i].offset;
-		int alen = urb->iso_frame_desc[i].actual_length;
-		if (alen > 0) {
-			if (buf[0] == 0x88) {
-				ntrans++;
-				len += alen;
-			} else if (buf[0] == 0x22) {
-				printk(KERN_DEBUG
-						"= l=%d nt=%d bpp=%d\n",
-				len - 4 * ntrans, ntrans,
-				ntrans == 0 ? 0 : len / ntrans);
-				ntrans = 1;
-				len = alen;
-			} else
-				printk(KERN_DEBUG "!\n");
-		}
-		printk(KERN_DEBUG "   n=%d s=%d al=%d %x\n", i,
-		       urb->iso_frame_desc[i].status,
-		       urb->iso_frame_desc[i].actual_length,
-		       (unsigned int)
-				       *((unsigned char *)(urb->transfer_buffer +
-				       urb->iso_frame_desc[i].
-				       offset)));
-	}
-}
-#endif
-
-static inline int em28xx_isoc_video(struct em28xx *dev,struct em28xx_frame_t **f,
-				    unsigned long *lock_flags, unsigned char buf)
-{
-	if (!(buf & 0x01)) {
-		if ((*f)->state == F_GRABBING) {
-			/*previous frame is incomplete */
-			if ((*f)->fieldbytesused < dev->field_size) {
-				(*f)->state = F_ERROR;
-				em28xx_isocdbg ("dropping incomplete bottom field (%i missing bytes)",
-					 dev->field_size-(*f)->fieldbytesused);
-			} else {
-				(*f)->state = F_DONE;
-				(*f)->buf.bytesused = dev->frame_size;
-			}
-		}
-		if ((*f)->state == F_DONE || (*f)->state == F_ERROR) {
-			/* move current frame to outqueue and get next free buffer from inqueue */
-			spin_lock_irqsave(&dev-> queue_lock, *lock_flags);
-			list_move_tail(&(*f)->frame, &dev->outqueue);
-			if (!list_empty(&dev->inqueue))
-				(*f) = list_entry(dev-> inqueue.next,
-			struct em28xx_frame_t,frame);
-			else
-				(*f) = NULL;
-			spin_unlock_irqrestore(&dev->queue_lock,*lock_flags);
-		}
-		if (!(*f)) {
-			em28xx_isocdbg ("new frame but no buffer is free");
-			return -1;
-		}
-		do_gettimeofday(&(*f)->buf.timestamp);
-		(*f)->buf.sequence = ++dev->frame_count;
-		(*f)->buf.field = V4L2_FIELD_INTERLACED;
-		(*f)->state = F_GRABBING;
-		(*f)->buf.bytesused = 0;
-		(*f)->top_field = 1;
-		(*f)->fieldbytesused = 0;
-	} else {
-					/* acquiring bottom field */
-		if ((*f)->state == F_GRABBING) {
-			if (!(*f)->top_field) {
-				(*f)->state = F_ERROR;
-				em28xx_isocdbg ("unexpected begin of bottom field; discarding it");
-			} else if ((*f)-> fieldbytesused < dev->field_size - 172) {
-				(*f)->state = F_ERROR;
-				em28xx_isocdbg ("dropping incomplete top field (%i missing bytes)",
-					 dev->field_size-(*f)->fieldbytesused);
-			} else {
-				(*f)->top_field = 0;
-				(*f)->fieldbytesused = 0;
-			}
-		}
-	}
-	return (0);
-}
-
-static inline void em28xx_isoc_video_copy(struct em28xx *dev,
-					  struct em28xx_frame_t **f, unsigned char *buf, int len)
-{
-	void *fieldstart, *startwrite, *startread;
-	int linesdone, currlinedone, offset, lencopy,remain;
-
-	if(dev->frame_size != (*f)->buf.length){
-		em28xx_err("frame_size %i and buf.length %i are different!!!\n",dev->frame_size,(*f)->buf.length);
-		return;
-	}
-
-	if ((*f)->fieldbytesused + len > dev->field_size)
-		len =dev->field_size - (*f)->fieldbytesused;
-
-	if (buf[0] != 0x88 && buf[0] != 0x22) {
-		em28xx_isocdbg("frame is not complete\n");
-		startread = buf;
-		len+=4;
-	} else
-		startread = buf + 4;
-
-	remain = len;
-
-	if ((*f)->top_field)
-		fieldstart = (*f)->bufmem;
-	else
-		fieldstart = (*f)->bufmem + dev->bytesperline;
-
-	linesdone = (*f)->fieldbytesused / dev->bytesperline;
-	currlinedone = (*f)->fieldbytesused % dev->bytesperline;
-	offset = linesdone * dev->bytesperline * 2 + currlinedone;
-	startwrite = fieldstart + offset;
-	lencopy = dev->bytesperline - currlinedone;
-	lencopy = lencopy > remain ? remain : lencopy;
-
-	memcpy(startwrite, startread, lencopy);
-	remain -= lencopy;
-
-	while (remain > 0) {
-		startwrite += lencopy + dev->bytesperline;
-		startread += lencopy;
-		if (dev->bytesperline > remain)
-			lencopy = remain;
-		else
-			lencopy = dev->bytesperline;
-
-		memcpy(startwrite, startread, lencopy);
-		remain -= lencopy;
-	}
-
-	(*f)->fieldbytesused += len;
-}
-
-/*
- * em28xx_isoIrq()
- * handles the incoming isoc urbs and fills the frames from our inqueue
- */
-static void em28xx_isocIrq(struct urb *urb)
-{
-	struct em28xx *dev = urb->context;
-	int i, status;
-	struct em28xx_frame_t **f;
-	unsigned long lock_flags;
-
-	if (!dev)
-		return;
-#ifdef ENABLE_DEBUG_ISOC_FRAMES
-	if (isoc_debug>1)
-		em28xx_isoc_dump(urb);
-#endif
-
-	if (urb->status == -ENOENT)
-		return;
-
-	f = &dev->frame_current;
-
-	if (dev->stream == STREAM_INTERRUPT) {
-		dev->stream = STREAM_OFF;
-		if ((*f))
-			(*f)->state = F_QUEUED;
-		em28xx_isocdbg("stream interrupted");
-		wake_up_interruptible(&dev->wait_stream);
-	}
-
-	if ((dev->state & DEV_DISCONNECTED) || (dev->state & DEV_MISCONFIGURED))
-		return;
-
-	if (dev->stream == STREAM_ON && !list_empty(&dev->inqueue)) {
-		if (!(*f))
-			(*f) = list_entry(dev->inqueue.next,
-		struct em28xx_frame_t, frame);
-
-		for (i = 0; i < urb->number_of_packets; i++) {
-			unsigned char *buf = urb->transfer_buffer +
-					urb->iso_frame_desc[i].offset;
-			int len = urb->iso_frame_desc[i].actual_length - 4;
-
-			if (urb->iso_frame_desc[i].status) {
-				em28xx_isocdbg("data error: [%d] len=%d, status=%d", i,
-					urb->iso_frame_desc[i].actual_length,
-					urb->iso_frame_desc[i].status);
-				if (urb->iso_frame_desc[i].status != -EPROTO)
-					continue;
-			}
-			if (urb->iso_frame_desc[i].actual_length <= 0) {
-				em28xx_isocdbg("packet %d is empty",i);
-				continue;
-			}
-			if (urb->iso_frame_desc[i].actual_length >
-			    urb->iso_frame_desc[i].length) {
-				em28xx_isocdbg("packet bigger than packet size");
-				continue;
-			}
-			/*new frame */
-			if (buf[0] == 0x22 && buf[1] == 0x5a) {
-				em28xx_isocdbg("Video frame, length=%i!",len);
-
-				if (em28xx_isoc_video(dev,f,&lock_flags,buf[2]))
-				break;
-			} else if (buf[0]==0x33 && buf[1]==0x95 && buf[2]==0x00) {
-				em28xx_isocdbg("VBI HEADER!!!");
-			}
-
-			/* actual copying */
-			if ((*f)->state == F_GRABBING) {
-				em28xx_isoc_video_copy(dev,f,buf, len);
-			}
-		}
-	}
-
-	for (i = 0; i < urb->number_of_packets; i++) {
-		urb->iso_frame_desc[i].status = 0;
-		urb->iso_frame_desc[i].actual_length = 0;
-	}
-
-	urb->status = 0;
-	if ((status = usb_submit_urb(urb, GFP_ATOMIC))) {
-		em28xx_errdev("resubmit of urb failed (error=%i)\n", status);
-		dev->state |= DEV_MISCONFIGURED;
-	}
-	wake_up_interruptible(&dev->wait_frame);
-	return;
-}
-
-/*
- * em28xx_uninit_isoc()
- * deallocates the buffers and urbs allocated during em28xx_init_iosc()
- */
-void em28xx_uninit_isoc(struct em28xx *dev)
-{
-	int i;
-
-	for (i = 0; i < EM28XX_NUM_BUFS; i++) {
-		if (dev->urb[i]) {
-			usb_kill_urb(dev->urb[i]);
-			if (dev->transfer_buffer[i]) {
-				usb_buffer_free(dev->udev,
-						dev->urb[i]->transfer_buffer_length,
-						dev->transfer_buffer[i],
-						dev->urb[i]->transfer_dma);
-			}
-			usb_free_urb(dev->urb[i]);
-		}
-		dev->urb[i] = NULL;
-		dev->transfer_buffer[i] = NULL;
-	}
-	em28xx_capture_start(dev, 0);
-}
-
-/*
- * em28xx_init_isoc()
- * allocates transfer buffers and submits the urbs for isoc transfer
- */
-int em28xx_init_isoc(struct em28xx *dev)
-{
-	/* change interface to 3 which allows the biggest packet sizes */
-	int i, errCode;
-	int sb_size;
-
-	em28xx_set_alternate(dev);
-	sb_size = EM28XX_NUM_PACKETS * dev->max_pkt_size;
-
-	/* reset streaming vars */
-	dev->frame_current = NULL;
-	dev->frame_count = 0;
-
-	/* allocate urbs */
-	for (i = 0; i < EM28XX_NUM_BUFS; i++) {
-		struct urb *urb;
-		int j;
-		/* allocate transfer buffer */
-		urb = usb_alloc_urb(EM28XX_NUM_PACKETS, GFP_KERNEL);
-		if (!urb){
-			em28xx_errdev("cannot alloc urb %i\n", i);
-			em28xx_uninit_isoc(dev);
-			return -ENOMEM;
-		}
-		dev->transfer_buffer[i] = usb_buffer_alloc(dev->udev, sb_size,
-							   GFP_KERNEL,
-							   &urb->transfer_dma);
-		if (!dev->transfer_buffer[i]) {
-			em28xx_errdev
-					("unable to allocate %i bytes for transfer buffer %i\n",
-					 sb_size, i);
-			em28xx_uninit_isoc(dev);
-			usb_free_urb(urb);
-			return -ENOMEM;
-		}
-		memset(dev->transfer_buffer[i], 0, sb_size);
-		urb->dev = dev->udev;
-		urb->context = dev;
-		urb->pipe = usb_rcvisocpipe(dev->udev, 0x82);
-		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
-		urb->interval = 1;
-		urb->transfer_buffer = dev->transfer_buffer[i];
-		urb->complete = em28xx_isocIrq;
-		urb->number_of_packets = EM28XX_NUM_PACKETS;
-		urb->transfer_buffer_length = sb_size;
-		for (j = 0; j < EM28XX_NUM_PACKETS; j++) {
-			urb->iso_frame_desc[j].offset = j * dev->max_pkt_size;
-			urb->iso_frame_desc[j].length = dev->max_pkt_size;
-		}
-		dev->urb[i] = urb;
-	}
-
-	/* submit urbs */
-	em28xx_coredbg("Submitting %d urbs of %d packets (%d each)\n",
-		       EM28XX_NUM_BUFS, EM28XX_NUM_PACKETS, dev->max_pkt_size);
-	for (i = 0; i < EM28XX_NUM_BUFS; i++) {
-		errCode = usb_submit_urb(dev->urb[i], GFP_KERNEL);
-		if (errCode) {
-			em28xx_errdev("submit of urb %i failed (error=%i)\n", i,
-				      errCode);
-			em28xx_uninit_isoc(dev);
-			return errCode;
-		}
-	}
-
-	return 0;
-}
-
 int em28xx_set_alternate(struct em28xx *dev)
 {
 	int errCode, prev_alt = dev->alt;
diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index c7f074c6f22..182058ac843 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -54,6 +54,21 @@
 		printk(KERN_INFO "%s %s :"fmt, \
 			 dev->name, __func__ , ##arg); } while (0)
 
+static unsigned int isoc_debug;
+module_param(isoc_debug,int,0644);
+MODULE_PARM_DESC(isoc_debug,"enable debug messages [isoc transfers]");
+
+#define em28xx_isocdbg(fmt, arg...) do {\
+	if (isoc_debug) \
+		printk(KERN_INFO "%s %s :"fmt, \
+			 dev->name, __FUNCTION__ , ##arg); } while (0)
+
+#define BUFFER_TIMEOUT     msecs_to_jiffies(2000)  /* 2 seconds */
+
+/* Limits minimum and default number of buffers */
+#define EM28XX_MIN_BUF 4
+#define EM28XX_DEF_BUF 8
+
 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL");
@@ -107,6 +122,665 @@ static struct v4l2_queryctrl em28xx_qctrl[] = {
 
 static struct usb_driver em28xx_usb_driver;
 
+/* ------------------------------------------------------------------
+	DMA and thread functions
+   ------------------------------------------------------------------*/
+
+/*
+ * Announces that a buffer were filled and request the next
+ */
+static void inline buffer_filled (struct em28xx *dev,
+				  struct em28xx_dmaqueue *dma_q,
+				  struct em28xx_buffer *buf)
+{
+	/* Nobody is waiting something to be done, just return */
+	if (!waitqueue_active(&buf->vb.done)) {
+		mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
+
+		printk(KERN_ERR "em28xx: buffer underrun at %ld\n",
+				jiffies);
+
+		return;
+	}
+
+	/* Advice that buffer was filled */
+	em28xx_isocdbg("[%p/%d] wakeup\n", buf, buf->vb.i);
+	buf->vb.state = VIDEOBUF_DONE;
+	buf->vb.field_count++;
+	do_gettimeofday(&buf->vb.ts);
+
+	list_del(&buf->vb.queue);
+	wake_up(&buf->vb.done);
+}
+
+/*
+ * Identify the buffer header type and properly handles
+ */
+static void em28xx_copy_video(struct em28xx *dev,
+			      struct em28xx_dmaqueue  *dma_q,
+			      struct em28xx_buffer *buf,
+			      unsigned char *p,
+			      unsigned char *outp, unsigned long len)
+{
+	void *fieldstart, *startwrite, *startread;
+	int  linesdone, currlinedone, offset, lencopy,remain;
+
+	if(dev->frame_size != buf->vb.size){
+		em28xx_errdev("size %i and buf.length %lu are different!\n",
+			   dev->frame_size, buf->vb.size);
+		return;
+	}
+
+	if (dma_q->pos + len > buf->vb.size)
+		len = buf->vb.size - dma_q->pos;
+
+	if (outp[0] != 0x88 && outp[0] != 0x22) {
+		em28xx_isocdbg("frame is not complete\n");
+		len += 4;
+	} else
+		p +=4;
+
+	startread = p;
+	remain = len;
+
+	/* Interlaces frame */
+	if (buf->top_field)
+		fieldstart = outp;
+	else
+		fieldstart = outp + dev->bytesperline;
+
+	linesdone = dma_q->pos / dev->bytesperline;
+	currlinedone = dma_q->pos % dev->bytesperline;
+	offset = linesdone * dev->bytesperline * 2 + currlinedone;
+	startwrite = fieldstart + offset;
+	lencopy = dev->bytesperline - currlinedone;
+	lencopy = lencopy > remain ? remain : lencopy;
+
+	if (__copy_to_user(startwrite, startread, lencopy) != 0)
+		em28xx_errdev("copy_to_user failed.\n");
+
+	remain -= lencopy;
+
+	while (remain > 0) {
+		startwrite += lencopy + dev->bytesperline;
+		startread += lencopy;
+		if (dev->bytesperline > remain)
+			lencopy = remain;
+		else
+			lencopy = dev->bytesperline;
+
+		if (__copy_to_user(startwrite, startread, lencopy) != 0)
+			em28xx_errdev("copy_to_user failed.\n");
+
+		remain -= lencopy;
+	}
+
+	dma_q->pos += len;
+}
+
+static void inline print_err_status (struct em28xx *dev,
+				     int packet, int status)
+{
+	char *errmsg = "Unknown";
+
+	switch(status) {
+	case -ENOENT:
+		errmsg = "unlinked synchronuously";
+		break;
+	case -ECONNRESET:
+		errmsg = "unlinked asynchronuously";
+		break;
+	case -ENOSR:
+		errmsg = "Buffer error (overrun)";
+		break;
+	case -EPIPE:
+		errmsg = "Stalled (device not responding)";
+		break;
+	case -EOVERFLOW:
+		errmsg = "Babble (bad cable?)";
+		break;
+	case -EPROTO:
+		errmsg = "Bit-stuff error (bad cable?)";
+		break;
+	case -EILSEQ:
+		errmsg = "CRC/Timeout (could be anything)";
+		break;
+	case -ETIME:
+		errmsg = "Device does not respond";
+		break;
+	}
+	if (packet<0) {
+		em28xx_isocdbg("URB status %d [%s].\n",	status, errmsg);
+	} else {
+		em28xx_isocdbg("URB packet %d, status %d [%s].\n",
+			       packet, status, errmsg);
+	}
+}
+
+/*
+ * video-buf generic routine to get the next available buffer
+ */
+static int inline get_next_buf (struct em28xx_dmaqueue *dma_q,
+					  struct em28xx_buffer **buf)
+{
+	struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
+
+	if (list_empty(&dma_q->active)) {
+		em28xx_isocdbg("No active queue to serve\n");
+		return 0;
+	}
+
+	*buf = list_entry(dma_q->active.next, struct em28xx_buffer, vb.queue);
+
+	return 1;
+}
+
+/*
+ * Controls the isoc copy of each urb packet
+ */
+static inline int em28xx_isoc_copy(struct urb *urb, struct em28xx_buffer **buf)
+{
+	struct em28xx_dmaqueue  *dma_q = urb->context;
+	struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
+	unsigned char *outp = videobuf_to_vmalloc (&(*buf)->vb);
+	int i, len = 0, rc = 1;
+	char *p;
+
+	if (!dev)
+		return 0;
+
+	if ((dev->state & DEV_DISCONNECTED) || (dev->state & DEV_MISCONFIGURED))
+		return 0;
+
+	if (urb->status<0) {
+		print_err_status (dev,-1,urb->status);
+		if (urb->status == -ENOENT)
+			return 0;
+	}
+
+	for (i = 0; i < urb->number_of_packets; i++) {
+		int status = urb->iso_frame_desc[i].status;
+
+		if (status<0) {
+			print_err_status (dev,i,status);
+			if (urb->iso_frame_desc[i].status != -EPROTO)
+				continue;
+		}
+
+		len=urb->iso_frame_desc[i].actual_length - 4;
+
+		if (urb->iso_frame_desc[i].actual_length <= 0) {
+			em28xx_isocdbg("packet %d is empty",i);
+			continue;
+		}
+		if (urb->iso_frame_desc[i].actual_length >
+						dev->max_pkt_size) {
+			em28xx_isocdbg("packet bigger than packet size");
+			continue;
+		}
+
+		p = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
+		if (urb->iso_frame_desc[i].status != -EPROTO)
+			continue;
+
+		/* FIXME: incomplete buffer checks where removed to make
+		   logic simpler. Impacts of those changes should be evaluated
+		 */
+		if (outp[0] == 0x22 && outp[1] == 0x5a) {
+			em28xx_isocdbg("Video frame, length=%i, %s", len,
+					(outp[2] == 1)? "top" : "botton");
+
+			if (outp[2] == 1) {
+				if ((*buf)->receiving)
+					buffer_filled (dev, dma_q, *buf);
+
+				(*buf)->top_field = 1;
+			} else {
+				(*buf)->top_field = 0;
+			}
+			(*buf)->receiving = 1;
+			dma_q->pos = 0;
+		} else if (outp[0]==0x33 && outp[1]==0x95 && outp[2]==0x00) {
+			em28xx_isocdbg("VBI HEADER!!!");
+		}
+
+		em28xx_copy_video(dev, dma_q, *buf, p, outp, len);
+
+		/* FIXME: Should add vbi copy */
+	}
+	return rc;
+}
+
+/* ------------------------------------------------------------------
+	URB control
+   ------------------------------------------------------------------*/
+
+/*
+ * IRQ callback, called by URB callback
+ */
+static void em28xx_irq_callback(struct urb *urb)
+{
+	struct em28xx_buffer    *buf;
+	struct em28xx_dmaqueue  *dma_q = urb->context;
+	struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
+	int rc,i;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->slock,flags);
+
+	buf=dev->isoc_ctl.buf;
+
+	if (!buf) {
+		rc=get_next_buf (dma_q, &buf);
+		if (rc<=0)
+			goto ret;
+	}
+
+	/* Copy data from URB */
+	rc=em28xx_isoc_copy(urb, &buf);
+
+	dev->isoc_ctl.buf=buf;
+ret:
+	/* Reset urb buffers */
+	for (i = 0; i < urb->number_of_packets; i++) {
+		urb->iso_frame_desc[i].status = 0;
+		urb->iso_frame_desc[i].actual_length = 0;
+	}
+	urb->status = 0;
+
+	if ((urb->status = usb_submit_urb(urb, GFP_ATOMIC))) {
+		em28xx_err("urb resubmit failed (error=%i)\n",
+			urb->status);
+	}
+
+	if (rc >= 0)
+			mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
+	spin_unlock_irqrestore(&dev->slock,flags);
+}
+
+/*
+ * Stop and Deallocate URBs
+ */
+static void em28xx_uninit_isoc(struct em28xx *dev)
+{
+	struct urb *urb;
+	int i;
+
+	dev->isoc_ctl.nfields=-1;
+	dev->isoc_ctl.buf=NULL;
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+		urb=dev->isoc_ctl.urb[i];
+		if (urb) {
+			usb_kill_urb(urb);
+			usb_unlink_urb(urb);
+			if (dev->isoc_ctl.transfer_buffer[i]) {
+				usb_buffer_free(dev->udev,
+						urb->transfer_buffer_length,
+						dev->isoc_ctl.transfer_buffer[i],
+						urb->transfer_dma);
+			}
+			usb_free_urb(urb);
+			dev->isoc_ctl.urb[i] = NULL;
+		}
+		dev->isoc_ctl.transfer_buffer[i] = NULL;
+	}
+
+	kfree (dev->isoc_ctl.urb);
+	kfree (dev->isoc_ctl.transfer_buffer);
+	dev->isoc_ctl.urb=NULL;
+	dev->isoc_ctl.transfer_buffer=NULL;
+
+	dev->isoc_ctl.num_bufs=0;
+
+	em28xx_capture_start(dev, 0);
+}
+
+/*
+ * Stop video thread - FIXME: Can be easily removed
+ */
+static void em28xx_stop_thread(struct em28xx_dmaqueue *dma_q)
+{
+	struct em28xx *dev= container_of(dma_q, struct em28xx, vidq);
+
+	em28xx_uninit_isoc(dev);
+}
+
+/*
+ * Allocate URBs and start IRQ
+ */
+static int em28xx_prepare_isoc(struct em28xx *dev, int max_packets,
+			       int num_bufs)
+{
+	struct em28xx_dmaqueue *dma_q = &dev->vidq;
+	int i;
+	int sb_size, pipe;
+	struct urb *urb;
+	int j, k;
+
+	/* De-allocates all pending stuff */
+	em28xx_uninit_isoc(dev);
+
+	dev->isoc_ctl.num_bufs = num_bufs;
+
+	dev->isoc_ctl.urb = kmalloc(sizeof(void *)*num_bufs,  GFP_KERNEL);
+	if (!dev->isoc_ctl.urb) {
+		em28xx_errdev("cannot alloc memory for usb buffers\n");
+		return -ENOMEM;
+	}
+
+	dev->isoc_ctl.transfer_buffer = kmalloc(sizeof(void *)*num_bufs,
+					      GFP_KERNEL);
+	if (!dev->isoc_ctl.urb) {
+		em28xx_errdev("cannot allocate memory for usbtransfer\n");
+		kfree(dev->isoc_ctl.urb);
+		return -ENOMEM;
+	}
+
+	dev->isoc_ctl.max_pkt_size = dev->max_pkt_size;
+
+	sb_size = max_packets * dev->isoc_ctl.max_pkt_size;
+
+	/* allocate urbs and transfer buffers */
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+		urb = usb_alloc_urb(max_packets, GFP_KERNEL);
+		if (!urb) {
+			em28xx_err("cannot alloc isoc_ctl.urb %i\n", i);
+			em28xx_uninit_isoc(dev);
+			usb_free_urb(urb);
+			return -ENOMEM;
+		}
+		dev->isoc_ctl.urb[i] = urb;
+
+		dev->isoc_ctl.transfer_buffer[i] = usb_buffer_alloc(dev->udev,
+			sb_size, GFP_KERNEL, &urb->transfer_dma);
+		if (!dev->isoc_ctl.transfer_buffer[i]) {
+			em28xx_err ("unable to allocate %i bytes for transfer"
+					" buffer %i%s\n",
+					sb_size, i,
+					in_interrupt()?" while in int":"");
+			em28xx_uninit_isoc(dev);
+			return -ENOMEM;
+		}
+		memset(dev->isoc_ctl.transfer_buffer[i], 0, sb_size);
+
+		/* FIXME: this is a hack - should be
+			'desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK'
+			should also be using 'desc.bInterval'
+		 */
+		pipe=usb_rcvisocpipe(dev->udev, 0x82);
+		usb_fill_int_urb(urb, dev->udev, pipe,
+				 dev->isoc_ctl.transfer_buffer[i], sb_size,
+				 em28xx_irq_callback, dma_q, 1);
+
+		urb->number_of_packets = max_packets;
+		urb->transfer_flags = URB_ISO_ASAP;
+
+		k = 0;
+		for (j = 0; j < max_packets; j++) {
+			urb->iso_frame_desc[j].offset = k;
+			urb->iso_frame_desc[j].length =
+						dev->isoc_ctl.max_pkt_size;
+			k += dev->isoc_ctl.max_pkt_size;
+		}
+	}
+
+	return 0;
+}
+
+static int em28xx_start_thread( struct em28xx_dmaqueue  *dma_q,
+				struct em28xx_buffer *buf)
+{
+	struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
+	int i,rc;
+
+	init_waitqueue_head(&dma_q->wq);
+
+	em28xx_capture_start(dev, 1);
+
+	/* submit urbs and enables IRQ */
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+		rc = usb_submit_urb(dev->isoc_ctl.urb[i], GFP_ATOMIC);
+		if (rc) {
+			em28xx_err("submit of urb %i failed (error=%i)\n", i,
+				   rc);
+			em28xx_uninit_isoc(dev);
+			return rc;
+		}
+	}
+
+	if (rc<0)
+		return rc;
+
+	return 0;
+}
+
+static int restart_video_queue(struct em28xx_dmaqueue *dma_q)
+{
+	struct em28xx *dev= container_of(dma_q,struct em28xx,vidq);
+
+	struct em28xx_buffer *buf, *prev;
+	struct list_head *item;
+
+	em28xx_videodbg("%s dma_q=0x%08lx\n",
+			__FUNCTION__,(unsigned long)dma_q);
+
+	if (!list_empty(&dma_q->active)) {
+		buf = list_entry(dma_q->active.next, struct em28xx_buffer, vb.queue);
+		em28xx_videodbg("restart_queue [%p/%d]: restart dma\n",
+				buf, buf->vb.i);
+		em28xx_stop_thread(dma_q);
+		em28xx_start_thread(dma_q, buf);
+
+		/* cancel all outstanding capture / vbi requests */
+		list_for_each(item,&dma_q->active) {
+			buf = list_entry(item, struct em28xx_buffer, vb.queue);
+
+			list_del(&buf->vb.queue);
+			buf->vb.state = VIDEOBUF_ERROR;
+			wake_up(&buf->vb.done);
+		}
+		mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
+
+		return 0;
+	}
+
+	prev = NULL;
+	for (;;) {
+		if (list_empty(&dma_q->queued))
+			return 0;
+		buf = list_entry(dma_q->queued.next, struct em28xx_buffer, vb.queue);
+		if (NULL == prev) {
+			list_del(&buf->vb.queue);
+			list_add_tail(&buf->vb.queue,&dma_q->active);
+
+			em28xx_videodbg("Restarting video dma\n");
+			em28xx_stop_thread(dma_q);
+			em28xx_start_thread(dma_q, buf);
+
+			buf->vb.state = VIDEOBUF_ACTIVE;
+			mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
+			em28xx_videodbg("[%p/%d] restart_queue -"
+					" first active\n", buf, buf->vb.i);
+
+		} else if (prev->vb.width  == buf->vb.width  &&
+			   prev->vb.height == buf->vb.height &&
+			   prev->fmt       == buf->fmt) {
+			list_del(&buf->vb.queue);
+			list_add_tail(&buf->vb.queue,&dma_q->active);
+			buf->vb.state = VIDEOBUF_ACTIVE;
+			em28xx_videodbg("[%p/%d] restart_queue -"
+					" move to active\n",buf,buf->vb.i);
+		} else {
+			return 0;
+		}
+		prev = buf;
+	}
+}
+
+static void em28xx_vid_timeout(unsigned long data)
+{
+	struct em28xx      *dev  = (struct em28xx*)data;
+	struct em28xx_dmaqueue *vidq = &dev->vidq;
+	struct em28xx_buffer   *buf;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->slock,flags);
+	while (!list_empty(&vidq->active)) {
+		buf = list_entry(vidq->active.next, struct em28xx_buffer,
+								 vb.queue);
+		list_del(&buf->vb.queue);
+		buf->vb.state = VIDEOBUF_ERROR;
+		wake_up(&buf->vb.done);
+		em28xx_videodbg("em28xx/0: [%p/%d] timeout\n",
+				buf, buf->vb.i);
+	}
+
+	restart_video_queue(vidq);
+	spin_unlock_irqrestore(&dev->slock,flags);
+}
+
+/* ------------------------------------------------------------------
+	Videobuf operations
+   ------------------------------------------------------------------*/
+
+static int
+buffer_setup(struct videobuf_queue *vq, unsigned int *count, unsigned int *size)
+{
+	struct em28xx_fh *fh = vq->priv_data;
+
+	*size = 16 * fh->width * fh->height >> 3;
+	if (0 == *count)
+		*count = EM28XX_DEF_BUF;
+
+	if (*count < EM28XX_MIN_BUF) {
+		*count=EM28XX_MIN_BUF;
+	}
+
+	return 0;
+}
+
+static void free_buffer(struct videobuf_queue *vq, struct em28xx_buffer *buf)
+{
+	if (in_interrupt())
+		BUG();
+
+	videobuf_waiton(&buf->vb, 0, 0);
+	videobuf_vmalloc_free(&buf->vb);
+	buf->vb.state = VIDEOBUF_NEEDS_INIT;
+}
+
+static int
+buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
+						enum v4l2_field field)
+{
+	struct em28xx_fh     *fh  = vq->priv_data;
+	struct em28xx_buffer *buf = container_of(vb,struct em28xx_buffer,vb);
+	struct em28xx        *dev = fh->dev;
+	int                  rc = 0, urb_init = 0;
+	const int            urbsize = EM28XX_NUM_PACKETS * dev->max_pkt_size;
+
+	BUG_ON(NULL == fh->fmt);
+
+	/* FIXME: It assumes depth = 16 */
+	/* The only currently supported format is 16 bits/pixel */
+	buf->vb.size = 16 * fh->width * fh->height >> 3;
+
+	if (0 != buf->vb.baddr  &&  buf->vb.bsize < buf->vb.size)
+		return -EINVAL;
+
+	if (buf->fmt       != fh->fmt    ||
+	    buf->vb.width  != fh->width  ||
+	    buf->vb.height != fh->height ||
+	    buf->vb.field  != field) {
+		buf->fmt       = fh->fmt;
+		buf->vb.width  = fh->width;
+		buf->vb.height = fh->height;
+		buf->vb.field  = field;
+		buf->vb.state = VIDEOBUF_NEEDS_INIT;
+	}
+
+	if (VIDEOBUF_NEEDS_INIT == buf->vb.state) {
+		if (0 != (rc = videobuf_iolock(vq,&buf->vb,NULL)))
+			goto fail;
+		urb_init=1;
+	}
+
+
+	if (!dev->isoc_ctl.num_bufs)
+		urb_init=1;
+
+	if (urb_init) {
+		rc = em28xx_prepare_isoc(dev, urbsize, EM28XX_NUM_BUFS);
+		if (rc<0)
+			goto fail;
+	}
+
+	buf->vb.state = VIDEOBUF_PREPARED;
+	return 0;
+
+fail:
+	free_buffer(vq,buf);
+	return rc;
+}
+
+static void
+buffer_queue(struct videobuf_queue *vq, struct videobuf_buffer *vb)
+{
+	struct em28xx_buffer    *buf     = container_of(vb, struct em28xx_buffer, vb);
+	struct em28xx_fh        *fh      = vq->priv_data;
+	struct em28xx      *dev     = fh->dev;
+	struct em28xx_dmaqueue  *vidq    = &dev->vidq;
+	struct em28xx_buffer    *prev;
+
+	if (!list_empty(&vidq->queued)) {
+		list_add_tail(&buf->vb.queue,&vidq->queued);
+		buf->vb.state = VIDEOBUF_QUEUED;
+		em28xx_videodbg("[%p/%d] buffer_queue - append to queued\n",
+				buf, buf->vb.i);
+	} else if (list_empty(&vidq->active)) {
+		list_add_tail(&buf->vb.queue,&vidq->active);
+		buf->vb.state = VIDEOBUF_ACTIVE;
+		mod_timer(&vidq->timeout, jiffies+BUFFER_TIMEOUT);
+		em28xx_videodbg("[%p/%d] buffer_queue - first active\n",
+				buf, buf->vb.i);
+		em28xx_start_thread(vidq, buf);
+	} else {
+		prev = list_entry(vidq->active.prev, struct em28xx_buffer,
+				  vb.queue);
+		if (prev->vb.width  == buf->vb.width  &&
+		    prev->vb.height == buf->vb.height &&
+		    prev->fmt       == buf->fmt) {
+			list_add_tail(&buf->vb.queue,&vidq->active);
+			buf->vb.state = VIDEOBUF_ACTIVE;
+			em28xx_videodbg("[%p/%d] buffer_queue -"
+					" append to active\n", buf, buf->vb.i);
+		} else {
+			list_add_tail(&buf->vb.queue,&vidq->queued);
+			buf->vb.state = VIDEOBUF_QUEUED;
+			em28xx_videodbg("[%p/%d] buffer_queue - first queued\n",
+					buf, buf->vb.i);
+		}
+	}
+}
+
+static void buffer_release(struct videobuf_queue *vq, struct videobuf_buffer *vb)
+{
+	struct em28xx_buffer   *buf  = container_of(vb,struct em28xx_buffer,vb);
+	struct em28xx_fh       *fh   = vq->priv_data;
+	struct em28xx          *dev  = (struct em28xx*)fh->dev;
+	struct em28xx_dmaqueue *vidq = &dev->vidq;
+
+	em28xx_stop_th