pwc-if.c

Linux support for Philips USB webcams halted Latest version: pwc-9.0.2.tar.gz (including documents

   Whatever strategy you choose, it always remains a tradeoff: with more
   frame buffers the chances of a missed frame are reduced. On the other
   hand, on slower machines it introduces lag because the queue will
   always be full.
 */

/**
  \brief Find next frame buffer to fill. Take from empty or full list, whichever comes first.
 */
static inline int pwc_next_fill_frame(struct pwc_device *pdev)
{
	int ret;
	unsigned long flags;

	ret = 0;
	spin_lock_irqsave(&pdev->ptrlock, flags);
	if (pdev->fill_frame != NULL) {
		/* append to 'full' list */
		if (pdev->full_frames == NULL) {
			pdev->full_frames = pdev->fill_frame;
			pdev->full_frames_tail = pdev->full_frames;
		}
		else {
			pdev->full_frames_tail->next = pdev->fill_frame;
			pdev->full_frames_tail = pdev->fill_frame;
		}
	}
	if (pdev->empty_frames != NULL) {
		/* We have empty frames available. That's easy */
		pdev->fill_frame = pdev->empty_frames;
		pdev->empty_frames = pdev->empty_frames->next;
	}
	else {
		/* Hmm. Take it from the full list */
#if PWC_DEBUG
		/* sanity check */
		if (pdev->full_frames == NULL) {
			Err("Neither empty or full frames available!\n");
			spin_unlock_irqrestore(&pdev->ptrlock, flags);
			return -EINVAL;
		}
#endif
		pdev->fill_frame = pdev->full_frames;
		pdev->full_frames = pdev->full_frames->next;
		ret = 1;
	}
	pdev->fill_frame->next = NULL;
#if PWC_DEBUG
	Trace(TRACE_SEQUENCE, "Assigning sequence number %d.\n", pdev->sequence);
	pdev->fill_frame->sequence = pdev->sequence++;
#endif
	spin_unlock_irqrestore(&pdev->ptrlock, flags);
	return ret;
}


/**
  \brief Reset all buffers, pointers and lists, except for the image_used[] buffer.

  If the image_used[] buffer is cleared too, mmap()/VIDIOCSYNC will run into trouble.
 */
static void pwc_reset_buffers(struct pwc_device *pdev)
{
	int i;
	unsigned long flags;

	spin_lock_irqsave(&pdev->ptrlock, flags);
	pdev->full_frames = NULL;
	pdev->full_frames_tail = NULL;
	for (i = 0; i < default_fbufs; i++) {
		pdev->fbuf[i].filled = 0;
		if (i > 0)
			pdev->fbuf[i].next = &pdev->fbuf[i - 1];
		else
			pdev->fbuf->next = NULL;
	}
	pdev->empty_frames = &pdev->fbuf[default_fbufs - 1];
	pdev->empty_frames_tail = pdev->fbuf;
	pdev->read_frame = NULL;
	pdev->fill_frame = pdev->empty_frames;
	pdev->empty_frames = pdev->empty_frames->next;

	pdev->image_read_pos = 0;
	pdev->fill_image = 0;
	spin_unlock_irqrestore(&pdev->ptrlock, flags);
}


/**
  \brief Do all the handling for getting one frame: get pointer, decompress, advance pointers.
 */
static int pwc_handle_frame(struct pwc_device *pdev)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&pdev->ptrlock, flags);
	/* First grab our read_frame; this is removed from all lists, so
	   we can release the lock after this without problems */
	if (pdev->read_frame != NULL) {
		/* This can't theoretically happen */
		Err("Huh? Read frame still in use?\n");
	}
	else {
		if (pdev->full_frames == NULL) {
			Err("Woops. No frames ready.\n");
		}
		else {
			pdev->read_frame = pdev->full_frames;
			pdev->full_frames = pdev->full_frames->next;
			pdev->read_frame->next = NULL;
		}

		if (pdev->read_frame != NULL) {
#if PWC_DEBUG
			Trace(TRACE_SEQUENCE, "Decompressing frame %d\n", pdev->read_frame->sequence);
#endif
			/* Decompression is a lenghty process, so it's outside of the lock.
			   This gives the isoc_handler the opportunity to fill more frames
			   in the mean time.
			*/
			spin_unlock_irqrestore(&pdev->ptrlock, flags);
			ret = pwc_decompress(pdev);
			spin_lock_irqsave(&pdev->ptrlock, flags);

			/* We're done with read_buffer, tack it to the end of the empty buffer list */
			if (pdev->empty_frames == NULL) {
				pdev->empty_frames = pdev->read_frame;
				pdev->empty_frames_tail = pdev->empty_frames;
			}
			else {
				pdev->empty_frames_tail->next = pdev->read_frame;
				pdev->empty_frames_tail = pdev->read_frame;
			}
			pdev->read_frame = NULL;
		}
	}
	spin_unlock_irqrestore(&pdev->ptrlock, flags);
	return ret;
}

/**
  \brief Advance pointers of image buffer (after each user request)
*/
static inline void pwc_next_image(struct pwc_device *pdev)
{
	pdev->image_used[pdev->fill_image] = 0;
	pdev->fill_image = (pdev->fill_image + 1) % default_mbufs;
}


/* This gets called for the Isochronous pipe (video). This is done in
 * interrupt time, so it has to be fast, not crash, and not stall. Neat.
 */
static void pwc_isoc_handler(struct urb *urb, struct pt_regs *regs)
{
	struct pwc_device *pdev;
	int i, fst, flen;
	int awake;
	struct pwc_frame_buf *fbuf;
	unsigned char *fillptr = NULL;
	unsigned char *iso_buf = NULL;

	awake = 0;
	pdev = (struct pwc_device *)urb->context;
	if (pdev == NULL) {
		Err("isoc_handler() called with NULL device?!\n");
		return;
	}
#ifdef PWC_MAGIC
	if (pdev->magic != PWC_MAGIC) {
		Err("isoc_handler() called with bad magic!\n");
		return;
	}
#endif
	if (urb->status == -ENOENT || urb->status == -ECONNRESET) {
		Trace(TRACE_OPEN, "pwc_isoc_handler(): URB (%p) unlinked %ssynchronuously.\n", urb, urb->status == -ENOENT ? "" : "a");
		return;
	}
	if (urb->status != -EINPROGRESS && urb->status != 0) {
		const char *errmsg;

		errmsg = "Unknown";
		switch(urb->status) {
			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 -ETIMEDOUT:	errmsg = "NAK (device does not respond)"; break;
		}
		Trace(TRACE_FLOW, "pwc_isoc_handler() called with status %d [%s].\n", urb->status, errmsg);
		/* Give up after a number of contiguous errors on the USB bus. 
		   Appearantly something is wrong so we simulate an unplug event.
		 */
		if (++pdev->visoc_errors > MAX_ISOC_ERRORS)
		{
			Info("Too many ISOC errors, bailing out.\n");
			pdev->error_status = EIO;
			awake = 1;
			wake_up_interruptible(&pdev->frameq);
		}
		goto handler_end; // ugly, but practical
	}

	fbuf = pdev->fill_frame;
	if (fbuf == NULL) {
		Err("pwc_isoc_handler without valid fill frame.\n");
		awake = 1;
		goto handler_end;
	}
	else {
		fillptr = fbuf->data + fbuf->filled;
	}

	/* Reset ISOC error counter. We did get here, after all. */
	pdev->visoc_errors = 0;

	/* vsync: 0 = don't copy data
	          1 = sync-hunt
	          2 = synched
	 */
	/* Compact data */
	for (i = 0; i < urb->number_of_packets; i++) {
		fst  = urb->iso_frame_desc[i].status;
		flen = urb->iso_frame_desc[i].actual_length;
		iso_buf = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
		if (fst == 0) {
			if (flen > 0) { /* if valid data... */
				if (pdev->vsync > 0) { /* ...and we are not sync-hunting... */
					pdev->vsync = 2;

					/* ...copy data to frame buffer, if possible */
					if (flen + fbuf->filled > pdev->frame_total_size) {
						Trace(TRACE_FLOW, "Frame buffer overflow (flen = %d, frame_total_size = %d).\n", flen, pdev->frame_total_size);
						pdev->vsync = 0; /* Hmm, let's wait for an EOF (end-of-frame) */
						pdev->vframes_error++;
					}
					else {
						memmove(fillptr, iso_buf, flen);
						fillptr += flen;
					}
				}
				fbuf->filled += flen;
			} /* ..flen > 0 */

			if (flen < pdev->vlast_packet_size) {
				/* Shorter packet... We probably have the end of an image-frame; 
				   wake up read() process and let select()/poll() do something.
				   Decompression is done in user time over there.
				 */
				if (pdev->vsync == 2) {
					/* The ToUCam Fun CMOS sensor causes the firmware to send 2 or 3 bogus 
					   frames on the USB wire after an exposure change. This conditition is 
					   however detected  in the cam and a bit is set in the header.
					 */
					if (pdev->type == 730) {
						unsigned char *ptr = (unsigned char *)fbuf->data;
						
						if (ptr[1] == 1 && ptr[0] & 0x10) {
#if PWC_DEBUG
							Debug("Hyundai CMOS sensor bug. Dropping frame %d.\n", fbuf->sequence);
#endif
							pdev->drop_frames += 2;
							pdev->vframes_error++;
						}
						if ((ptr[0] ^ pdev->vmirror) & 0x01) {
							if (ptr[0] & 0x01)
								Info("Snapshot button pressed.\n");
							else
								Info("Snapshot button released.\n");
						}
						if ((ptr[0] ^ pdev->vmirror) & 0x02) {
							if (ptr[0] & 0x02)
								Info("Image is mirrored.\n");
							else
								Info("Image is normal.\n");
						}
						pdev->vmirror = ptr[0] & 0x03;
						/* Sometimes the trailer of the 730 is still sent as a 4 byte packet 
						   after a short frame; this condition is filtered out specifically. A 4 byte
						   frame doesn't make sense anyway.
						   So we get either this sequence: 
						   	drop_bit set -> 4 byte frame -> short frame -> good frame
						   Or this one:
						   	drop_bit set -> short frame -> good frame
						   So we drop either 3 or 2 frames in all!
						 */
						if (fbuf->filled == 4)
							pdev->drop_frames++;
					}

					/* In case we were instructed to drop the frame, do so silently.
					   The buffer pointers are not updated either (but the counters are reset below).
					 */
					if (pdev->drop_frames > 0)
						pdev->drop_frames--;
					else {
						/* Check for underflow first */
						if (fbuf->filled < pdev->frame_total_size) {
							Trace(TRACE_FLOW, "Frame buffer underflow (%d bytes); discarded.\n", fbuf->filled);
							pdev->vframes_error++;
						}
						else {
							/* Send only once per EOF */
							awake = 1; /* delay wake_ups */

							/* Find our next frame to fill. This will always succeed, since we
							 * nick a frame from either empty or full list, but if we had to
							 * take it from the full list, it means a frame got dropped.
							 */
							if (pwc_next_fill_frame(pdev)) {
								pdev->vframes_dumped++;
								if ((pdev->vframe_count > FRAME_LOWMARK) && (pwc_trace & TRACE_FLOW)) {
									if (pdev->vframes_dumped < 20)
										Trace(TRACE_FLOW, "Dumping frame %d.\n", pdev->vframe_count);
									if (pdev->vframes_dumped == 20)
										Trace(TRACE_FLOW, "Dumping frame %d (last message).\n", pdev->vframe_count);
								}
							}
							fbuf = pdev->fill_frame;
						}
					} /* !drop_frames */
					pdev->vframe_count++;
				}
				fbuf->filled = 0;
				fillptr = fbuf->data;
				pdev->vsync = 1;
			} /* .. flen < last_packet_size */
			pdev->vlast_packet_size = flen;
		} /* ..status == 0 */
#if PWC_DEBUG
		/* This is normally not interesting to the user, unless you are really debugging something */
		else {
			static int iso_error = 0;
			iso_error++;
			if (iso_error < 20)
				Trace(TRACE_FLOW, "Iso frame %d of USB has error %d\n", i, fst);
		}
#endif
	}

handler_end:
	if (awake)
		wake_up_interruptible(&pdev->frameq);

	urb->dev = pdev->udev;
	i = usb_submit_urb(urb, GFP_ATOMIC);
	if (i != 0)
		Err("Error (%d) re-submitting urb in pwc_isoc_handler.\n", i);
}


static int pwc_isoc_init(struct pwc_device *pdev)
{
	struct usb_device *udev;
	struct urb *urb;
	int i, j, ret;

	struct usb_interface *intf;
	struct usb_host_interface *idesc = NULL;

	if (pdev == NULL)
		return -EFAULT;
	if (pdev->iso_init)
		return 0;
	pdev->vsync = 0;
	udev = pdev->udev;

	/* Get the current alternate interface, adjust packet size */
	if (!udev->actconfig)
		return -EFAULT;
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,5)
	idesc = &udev->actconfig->interface[0]->altsetting[pdev->valternate];
#else
	intf = usb_ifnum_to_if(udev, 0);
	if (intf)
		idesc = usb_altnum_to_altsetting(intf, pdev->valternate);
#endif
		
	if (!idesc)
		return -EFAULT;

	/* Search video endpoint */
	pdev->vmax_packet_size = -1;
	for (i = 0; i < idesc->desc.bNumEndpoints; i++)
		if ((idesc->endpoint[i].desc.bEndpointAddress & 0xF) == pdev->vendpoint) {
			pdev->vmax_packet_size = idesc->endpoint[i].desc.wMaxPacketSize;
			break;
		}
	
	if (pdev->vmax_packet_size < 0 || pdev->vmax_packet_size > ISO_MAX_FRAME_SIZE) {
		Err("Failed to find packet size for video endpoint in current alternate setting.\n");
		return -ENFILE; /* Odd error, that should be noticable */
	}

	/* Set alternate interface */
	ret = 0;
	Trace(TRACE_OPEN, "Setting alternate interface %d\n", pdev->valternate);
	ret = usb_set_interface(pdev->udev, 0, pdev->valternate);
	if (ret < 0)
		return ret;

	for (i = 0; i < MAX_ISO_BUFS; i++) {
		urb = usb_alloc_urb(ISO_FRAMES_PER_DESC, GFP_KERNEL);
		if (urb == NULL) {
			Err("Failed to allocate urb %d\n", i);
			ret = -ENOMEM;
			break;
		}
		pdev->sbuf[i].urb = urb;
		Trace(TRACE_MEMORY, "Allocated URB at 0x%p\n", urb);
	}
	if (ret) {
		/* De-allocate in reverse order */
		while (i >= 0) {
			if (pdev->sbuf[i].urb != NULL)
				usb_free_urb(pdev->sbuf[i].urb);
			pdev->sbuf[i].urb = NULL;
			i--;
		}
		return ret;
	}

	/* init URB structure */	
	for (i = 0; i < MAX_ISO_BUFS; i++) {
		urb = pdev->sbuf[i].urb;

		urb->interval = 1; // devik
		urb->dev = udev;
	        urb->pipe = usb_rcvisocpipe(udev, pdev->vendpoint);
		urb->transfer_flags = URB_ISO_ASAP;
	        urb->transfer_buffer = pdev->sbuf[i].data;