Contributors: 14
Author Tokens Token Proportion Commits Commit Proportion
Alan Cox 3941 88.48% 1 5.88%
Hans Verkuil 290 6.51% 3 17.65%
Mauro Carvalho Chehab 87 1.95% 2 11.76%
Wenwen Wang 38 0.85% 1 5.88%
Amit Choudhary 32 0.72% 1 5.88%
Douglas Schilling Landgraf 27 0.61% 1 5.88%
Pavel Skripkin 18 0.40% 1 5.88%
Oliver Neukum 8 0.18% 1 5.88%
Paul Gortmaker 3 0.07% 1 5.88%
Kees Cook 3 0.07% 1 5.88%
Shyam Saini 3 0.07% 1 5.88%
Thomas Gleixner 2 0.04% 1 5.88%
Arvind Yadav 1 0.02% 1 5.88%
Peter Senna Tschudin 1 0.02% 1 5.88%
Total 4454 17 


// SPDX-License-Identifier: GPL-2.0-or-later
/****************************************************************************
 *
 *  Filename: cpia2_usb.c
 *
 *  Copyright 2001, STMicrolectronics, Inc.
 *      Contact:  steve.miller@st.com
 *
 *  Description:
 *     This is a USB driver for CPia2 based video cameras.
 *     The infrastructure of this driver is based on the cpia usb driver by
 *     Jochen Scharrlach and Johannes Erdfeldt.
 *
 *  Stripped of 2.4 stuff ready for main kernel submit by
 *		Alan Cox <alan@lxorguk.ukuu.org.uk>
 ****************************************************************************/

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/module.h>

#include "cpia2.h"

static int frame_sizes[] = {
	0,	// USBIF_CMDONLY
	0,	// USBIF_BULK
	128,	// USBIF_ISO_1
	384,	// USBIF_ISO_2
	640,	// USBIF_ISO_3
	768,	// USBIF_ISO_4
	896,	// USBIF_ISO_5
	1023,	// USBIF_ISO_6
};

#define FRAMES_PER_DESC    10
#define FRAME_SIZE_PER_DESC   frame_sizes[cam->cur_alt]

static void process_frame(struct camera_data *cam);
static void cpia2_usb_complete(struct urb *urb);
static int cpia2_usb_probe(struct usb_interface *intf,
			   const struct usb_device_id *id);
static void cpia2_usb_disconnect(struct usb_interface *intf);
static int cpia2_usb_suspend(struct usb_interface *intf, pm_message_t message);
static int cpia2_usb_resume(struct usb_interface *intf);

static void free_sbufs(struct camera_data *cam);
static void add_APPn(struct camera_data *cam);
static void add_COM(struct camera_data *cam);
static int submit_urbs(struct camera_data *cam);
static int set_alternate(struct camera_data *cam, unsigned int alt);
static int configure_transfer_mode(struct camera_data *cam, unsigned int alt);

static const struct usb_device_id cpia2_id_table[] = {
	{USB_DEVICE(0x0553, 0x0100)},
	{USB_DEVICE(0x0553, 0x0140)},
	{USB_DEVICE(0x0553, 0x0151)},  /* STV0676 */
	{}			/* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, cpia2_id_table);

static struct usb_driver cpia2_driver = {
	.name		= "cpia2",
	.probe		= cpia2_usb_probe,
	.disconnect	= cpia2_usb_disconnect,
	.suspend	= cpia2_usb_suspend,
	.resume		= cpia2_usb_resume,
	.reset_resume	= cpia2_usb_resume,
	.id_table	= cpia2_id_table
};


/******************************************************************************
 *
 *  process_frame
 *
 *****************************************************************************/
static void process_frame(struct camera_data *cam)
{
	static int frame_count;

	unsigned char *inbuff = cam->workbuff->data;

	DBG("Processing frame #%d, current:%d\n",
	    cam->workbuff->num, cam->curbuff->num);

	if(cam->workbuff->length > cam->workbuff->max_length)
		cam->workbuff->max_length = cam->workbuff->length;

	if ((inbuff[0] == 0xFF) && (inbuff[1] == 0xD8)) {
		frame_count++;
	} else {
		cam->workbuff->status = FRAME_ERROR;
		DBG("Start of frame not found\n");
		return;
	}

	/***
	 * Now the output buffer should have a JPEG image in it.
	 ***/
	if(!cam->first_image_seen) {
		/* Always skip the first image after streaming
		 * starts. It is almost certainly corrupt. */
		cam->first_image_seen = 1;
		cam->workbuff->status = FRAME_EMPTY;
		return;
	}
	if (cam->workbuff->length > 3) {
		if(cam->mmapped &&
		   cam->workbuff->length < cam->workbuff->max_length) {
			/* No junk in the buffers */
			memset(cam->workbuff->data+cam->workbuff->length,
			       0, cam->workbuff->max_length-
				  cam->workbuff->length);
		}
		cam->workbuff->max_length = cam->workbuff->length;
		cam->workbuff->status = FRAME_READY;

		if(!cam->mmapped && cam->num_frames > 2) {
			/* During normal reading, the most recent
			 * frame will be read.  If the current frame
			 * hasn't started reading yet, it will never
			 * be read, so mark it empty.  If the buffer is
			 * mmapped, or we have few buffers, we need to
			 * wait for the user to free the buffer.
			 *
			 * NOTE: This is not entirely foolproof with 3
			 * buffers, but it would take an EXTREMELY
			 * overloaded system to cause problems (possible
			 * image data corruption).  Basically, it would
			 * need to take more time to execute cpia2_read
			 * than it would for the camera to send
			 * cam->num_frames-2 frames before problems
			 * could occur.
			 */
			cam->curbuff->status = FRAME_EMPTY;
		}
		cam->curbuff = cam->workbuff;
		cam->workbuff = cam->workbuff->next;
		DBG("Changed buffers, work:%d, current:%d\n",
		    cam->workbuff->num, cam->curbuff->num);
		return;
	} else {
		DBG("Not enough data for an image.\n");
	}

	cam->workbuff->status = FRAME_ERROR;
	return;
}

/******************************************************************************
 *
 *  add_APPn
 *
 *  Adds a user specified APPn record
 *****************************************************************************/
static void add_APPn(struct camera_data *cam)
{
	if(cam->APP_len > 0) {
		cam->workbuff->data[cam->workbuff->length++] = 0xFF;
		cam->workbuff->data[cam->workbuff->length++] = 0xE0+cam->APPn;
		cam->workbuff->data[cam->workbuff->length++] = 0;
		cam->workbuff->data[cam->workbuff->length++] = cam->APP_len+2;
		memcpy(cam->workbuff->data+cam->workbuff->length,
		       cam->APP_data, cam->APP_len);
		cam->workbuff->length += cam->APP_len;
	}
}

/******************************************************************************
 *
 *  add_COM
 *
 *  Adds a user specified COM record
 *****************************************************************************/
static void add_COM(struct camera_data *cam)
{
	if(cam->COM_len > 0) {
		cam->workbuff->data[cam->workbuff->length++] = 0xFF;
		cam->workbuff->data[cam->workbuff->length++] = 0xFE;
		cam->workbuff->data[cam->workbuff->length++] = 0;
		cam->workbuff->data[cam->workbuff->length++] = cam->COM_len+2;
		memcpy(cam->workbuff->data+cam->workbuff->length,
		       cam->COM_data, cam->COM_len);
		cam->workbuff->length += cam->COM_len;
	}
}

/******************************************************************************
 *
 *  cpia2_usb_complete
 *
 *  callback when incoming packet is received
 *****************************************************************************/
static void cpia2_usb_complete(struct urb *urb)
{
	int i;
	unsigned char *cdata;
	static bool frame_ready = false;
	struct camera_data *cam = (struct camera_data *) urb->context;

	if (urb->status!=0) {
		if (!(urb->status == -ENOENT ||
		      urb->status == -ECONNRESET ||
		      urb->status == -ESHUTDOWN))
		{
			DBG("urb->status = %d!\n", urb->status);
		}
		DBG("Stopping streaming\n");
		return;
	}

	if (!cam->streaming || !video_is_registered(&cam->vdev)) {
		LOG("Will now stop the streaming: streaming = %d, present=%d\n",
		    cam->streaming, video_is_registered(&cam->vdev));
		return;
	}

	/***
	 * Packet collater
	 ***/
	//DBG("Collating %d packets\n", urb->number_of_packets);
	for (i = 0; i < urb->number_of_packets; i++) {
		u16 checksum, iso_checksum;
		int j;
		int n = urb->iso_frame_desc[i].actual_length;
		int st = urb->iso_frame_desc[i].status;

		if(cam->workbuff->status == FRAME_READY) {
			struct framebuf *ptr;
			/* Try to find an available buffer */
			DBG("workbuff full, searching\n");
			for (ptr = cam->workbuff->next;
			     ptr != cam->workbuff;
			     ptr = ptr->next)
			{
				if (ptr->status == FRAME_EMPTY) {
					ptr->status = FRAME_READING;
					ptr->length = 0;
					break;
				}
			}
			if (ptr == cam->workbuff)
				break; /* No READING or EMPTY buffers left */

			cam->workbuff = ptr;
		}

		if (cam->workbuff->status == FRAME_EMPTY ||
		    cam->workbuff->status == FRAME_ERROR) {
			cam->workbuff->status = FRAME_READING;
			cam->workbuff->length = 0;
		}

		//DBG("   Packet %d length = %d, status = %d\n", i, n, st);
		cdata = urb->transfer_buffer + urb->iso_frame_desc[i].offset;

		if (st) {
			LOG("cpia2 data error: [%d] len=%d, status = %d\n",
			    i, n, st);
			if(!ALLOW_CORRUPT)
				cam->workbuff->status = FRAME_ERROR;
			continue;
		}

		if(n<=2)
			continue;

		checksum = 0;
		for(j=0; j<n-2; ++j)
			checksum += cdata[j];
		iso_checksum = cdata[j] + cdata[j+1]*256;
		if(checksum != iso_checksum) {
			LOG("checksum mismatch: [%d] len=%d, calculated = %x, checksum = %x\n",
			    i, n, (int)checksum, (int)iso_checksum);
			if(!ALLOW_CORRUPT) {
				cam->workbuff->status = FRAME_ERROR;
				continue;
			}
		}
		n -= 2;

		if(cam->workbuff->status != FRAME_READING) {
			if((0xFF == cdata[0] && 0xD8 == cdata[1]) ||
			   (0xD8 == cdata[0] && 0xFF == cdata[1] &&
			    0 != cdata[2])) {
				/* frame is skipped, but increment total
				 * frame count anyway */
				cam->frame_count++;
			}
			DBG("workbuff not reading, status=%d\n",
			    cam->workbuff->status);
			continue;
		}

		if (cam->frame_size < cam->workbuff->length + n) {
			ERR("buffer overflow! length: %d, n: %d\n",
			    cam->workbuff->length, n);
			cam->workbuff->status = FRAME_ERROR;
			if(cam->workbuff->length > cam->workbuff->max_length)
				cam->workbuff->max_length =
					cam->workbuff->length;
			continue;
		}

		if (cam->workbuff->length == 0) {
			int data_offset;
			if ((0xD8 == cdata[0]) && (0xFF == cdata[1])) {
				data_offset = 1;
			} else if((0xFF == cdata[0]) && (0xD8 == cdata[1])
				  && (0xFF == cdata[2])) {
				data_offset = 2;
			} else {
				DBG("Ignoring packet, not beginning!\n");
				continue;
			}
			DBG("Start of frame pattern found\n");
			cam->workbuff->ts = ktime_get_ns();
			cam->workbuff->seq = cam->frame_count++;
			cam->workbuff->data[0] = 0xFF;
			cam->workbuff->data[1] = 0xD8;
			cam->workbuff->length = 2;
			add_APPn(cam);
			add_COM(cam);
			memcpy(cam->workbuff->data+cam->workbuff->length,
			       cdata+data_offset, n-data_offset);
			cam->workbuff->length += n-data_offset;
		} else if (cam->workbuff->length > 0) {
			memcpy(cam->workbuff->data + cam->workbuff->length,
			       cdata, n);
			cam->workbuff->length += n;
		}

		if ((cam->workbuff->length >= 3) &&
		    (cam->workbuff->data[cam->workbuff->length - 3] == 0xFF) &&
		    (cam->workbuff->data[cam->workbuff->length - 2] == 0xD9) &&
		    (cam->workbuff->data[cam->workbuff->length - 1] == 0xFF)) {
			frame_ready = true;
			cam->workbuff->data[cam->workbuff->length - 1] = 0;
			cam->workbuff->length -= 1;
		} else if ((cam->workbuff->length >= 2) &&
		   (cam->workbuff->data[cam->workbuff->length - 2] == 0xFF) &&
		   (cam->workbuff->data[cam->workbuff->length - 1] == 0xD9)) {
			frame_ready = true;
		}

		if (frame_ready) {
			DBG("Workbuff image size = %d\n",cam->workbuff->length);
			process_frame(cam);

			frame_ready = false;

			if (waitqueue_active(&cam->wq_stream))
				wake_up_interruptible(&cam->wq_stream);
		}
	}

	if(cam->streaming) {
		/* resubmit */
		urb->dev = cam->dev;
		if ((i = usb_submit_urb(urb, GFP_ATOMIC)) != 0)
			ERR("%s: usb_submit_urb ret %d!\n", __func__, i);
	}
}

/******************************************************************************
 *
 * configure_transfer_mode
 *
 *****************************************************************************/
static int configure_transfer_mode(struct camera_data *cam, unsigned int alt)
{
	static unsigned char iso_regs[8][4] = {
		{0x00, 0x00, 0x00, 0x00},
		{0x00, 0x00, 0x00, 0x00},
		{0xB9, 0x00, 0x00, 0x7E},
		{0xB9, 0x00, 0x01, 0x7E},
		{0xB9, 0x00, 0x02, 0x7E},
		{0xB9, 0x00, 0x02, 0xFE},
		{0xB9, 0x00, 0x03, 0x7E},
		{0xB9, 0x00, 0x03, 0xFD}
	};
	struct cpia2_command cmd;
	unsigned char reg;

	if (!video_is_registered(&cam->vdev))
		return -ENODEV;

	/***
	 * Write the isoc registers according to the alternate selected
	 ***/
	cmd.direction = TRANSFER_WRITE;
	cmd.buffer.block_data[0] = iso_regs[alt][0];
	cmd.buffer.block_data[1] = iso_regs[alt][1];
	cmd.buffer.block_data[2] = iso_regs[alt][2];
	cmd.buffer.block_data[3] = iso_regs[alt][3];
	cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
	cmd.start = CPIA2_VC_USB_ISOLIM;
	cmd.reg_count = 4;
	cpia2_send_command(cam, &cmd);

	/***
	 * Enable relevant streams before starting polling.
	 * First read USB Stream Config Register.
	 ***/
	cmd.direction = TRANSFER_READ;
	cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
	cmd.start = CPIA2_VC_USB_STRM;
	cmd.reg_count = 1;
	cpia2_send_command(cam, &cmd);
	reg = cmd.buffer.block_data[0];

	/* Clear iso, bulk, and int */
	reg &= ~(CPIA2_VC_USB_STRM_BLK_ENABLE |
		 CPIA2_VC_USB_STRM_ISO_ENABLE |
		 CPIA2_VC_USB_STRM_INT_ENABLE);

	if (alt == USBIF_BULK) {
		DBG("Enabling bulk xfer\n");
		reg |= CPIA2_VC_USB_STRM_BLK_ENABLE;	/* Enable Bulk */
		cam->xfer_mode = XFER_BULK;
	} else if (alt >= USBIF_ISO_1) {
		DBG("Enabling ISOC xfer\n");
		reg |= CPIA2_VC_USB_STRM_ISO_ENABLE;
		cam->xfer_mode = XFER_ISOC;
	}

	cmd.buffer.block_data[0] = reg;
	cmd.direction = TRANSFER_WRITE;
	cmd.start = CPIA2_VC_USB_STRM;
	cmd.reg_count = 1;
	cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
	cpia2_send_command(cam, &cmd);

	return 0;
}

/******************************************************************************
 *
 * cpia2_usb_change_streaming_alternate
 *
 *****************************************************************************/
int cpia2_usb_change_streaming_alternate(struct camera_data *cam,
					 unsigned int alt)
{
	int ret = 0;

	if(alt < USBIF_ISO_1 || alt > USBIF_ISO_6)
		return -EINVAL;

	if(alt == cam->params.camera_state.stream_mode)
		return 0;

	cpia2_usb_stream_pause(cam);

	configure_transfer_mode(cam, alt);

	cam->params.camera_state.stream_mode = alt;

	/* Reset the camera to prevent image quality degradation */
	cpia2_reset_camera(cam);

	cpia2_usb_stream_resume(cam);

	return ret;
}

/******************************************************************************
 *
 * set_alternate
 *
 *****************************************************************************/
static int set_alternate(struct camera_data *cam, unsigned int alt)
{
	int ret = 0;

	if(alt == cam->cur_alt)
		return 0;

	if (cam->cur_alt != USBIF_CMDONLY) {
		DBG("Changing from alt %d to %d\n", cam->cur_alt, USBIF_CMDONLY);
		ret = usb_set_interface(cam->dev, cam->iface, USBIF_CMDONLY);
		if (ret != 0)
			return ret;
	}
	if (alt != USBIF_CMDONLY) {
		DBG("Changing from alt %d to %d\n", USBIF_CMDONLY, alt);
		ret = usb_set_interface(cam->dev, cam->iface, alt);
		if (ret != 0)
			return ret;
	}

	cam->old_alt = cam->cur_alt;
	cam->cur_alt = alt;

	return ret;
}

/******************************************************************************
 *
 * free_sbufs
 *
 * Free all cam->sbuf[]. All non-NULL .data and .urb members that are non-NULL
 * are assumed to be allocated. Non-NULL .urb members are also assumed to be
 * submitted (and must therefore be killed before they are freed).
 *****************************************************************************/
static void free_sbufs(struct camera_data *cam)
{
	int i;

	for (i = 0; i < NUM_SBUF; i++) {
		if(cam->sbuf[i].urb) {
			usb_kill_urb(cam->sbuf[i].urb);
			usb_free_urb(cam->sbuf[i].urb);
			cam->sbuf[i].urb = NULL;
		}
		if(cam->sbuf[i].data) {
			kfree(cam->sbuf[i].data);
			cam->sbuf[i].data = NULL;
		}
	}
}

/*******
* Convenience functions
*******/
/****************************************************************************
 *
 *  write_packet
 *
 ***************************************************************************/
static int write_packet(struct usb_device *udev,
			u8 request, u8 * registers, u16 start, size_t size)
{
	unsigned char *buf;
	int ret;

	if (!registers || size <= 0)
		return -EINVAL;

	buf = kmemdup(registers, size, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	ret = usb_control_msg(udev,
			       usb_sndctrlpipe(udev, 0),
			       request,
			       USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			       start,	/* value */
			       0,	/* index */
			       buf,	/* buffer */
			       size,
			       HZ);

	kfree(buf);
	return ret;
}

/****************************************************************************
 *
 *  read_packet
 *
 ***************************************************************************/
static int read_packet(struct usb_device *udev,
		       u8 request, u8 * registers, u16 start, size_t size)
{
	unsigned char *buf;
	int ret;

	if (!registers || size <= 0)
		return -EINVAL;

	buf = kmalloc(size, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	ret = usb_control_msg(udev,
			       usb_rcvctrlpipe(udev, 0),
			       request,
			       USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_DEVICE,
			       start,	/* value */
			       0,	/* index */
			       buf,	/* buffer */
			       size,
			       HZ);

	if (ret >= 0)
		memcpy(registers, buf, size);

	kfree(buf);

	return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_transfer_cmd
 *
 *****************************************************************************/
int cpia2_usb_transfer_cmd(struct camera_data *cam,
			   void *registers,
			   u8 request, u8 start, u8 count, u8 direction)
{
	int err = 0;
	struct usb_device *udev = cam->dev;

	if (!udev) {
		ERR("%s: Internal driver error: udev is NULL\n", __func__);
		return -EINVAL;
	}

	if (!registers) {
		ERR("%s: Internal driver error: register array is NULL\n", __func__);
		return -EINVAL;
	}

	if (direction == TRANSFER_READ) {
		err = read_packet(udev, request, (u8 *)registers, start, count);
		if (err > 0)
			err = 0;
	} else if (direction == TRANSFER_WRITE) {
		err =write_packet(udev, request, (u8 *)registers, start, count);
		if (err < 0) {
			LOG("Control message failed, err val = %d\n", err);
			LOG("Message: request = 0x%0X, start = 0x%0X\n",
			    request, start);
			LOG("Message: count = %d, register[0] = 0x%0X\n",
			    count, ((unsigned char *) registers)[0]);
		} else
			err=0;
	} else {
		LOG("Unexpected first byte of direction: %d\n",
		       direction);
		return -EINVAL;
	}

	if(err != 0)
		LOG("Unexpected error: %d\n", err);
	return err;
}


/******************************************************************************
 *
 *  submit_urbs
 *
 *****************************************************************************/
static int submit_urbs(struct camera_data *cam)
{
	struct urb *urb;
	int fx, err, i, j;

	for(i=0; i<NUM_SBUF; ++i) {
		if (cam->sbuf[i].data)
			continue;
		cam->sbuf[i].data =
		    kmalloc_array(FRAME_SIZE_PER_DESC, FRAMES_PER_DESC,
				  GFP_KERNEL);
		if (!cam->sbuf[i].data) {
			while (--i >= 0) {
				kfree(cam->sbuf[i].data);
				cam->sbuf[i].data = NULL;
			}
			return -ENOMEM;
		}
	}

	/* We double buffer the Isoc lists, and also know the polling
	 * interval is every frame (1 == (1 << (bInterval -1))).
	 */
	for(i=0; i<NUM_SBUF; ++i) {
		if(cam->sbuf[i].urb) {
			continue;
		}
		urb = usb_alloc_urb(FRAMES_PER_DESC, GFP_KERNEL);
		if (!urb) {
			for (j = 0; j < i; j++)
				usb_free_urb(cam->sbuf[j].urb);
			for (j = 0; j < NUM_SBUF; j++) {
				kfree(cam->sbuf[j].data);
				cam->sbuf[j].data = NULL;
			}
			return -ENOMEM;
		}

		cam->sbuf[i].urb = urb;
		urb->dev = cam->dev;
		urb->context = cam;
		urb->pipe = usb_rcvisocpipe(cam->dev, 1 /*ISOC endpoint*/);
		urb->transfer_flags = URB_ISO_ASAP;
		urb->transfer_buffer = cam->sbuf[i].data;
		urb->complete = cpia2_usb_complete;
		urb->number_of_packets = FRAMES_PER_DESC;
		urb->interval = 1;
		urb->transfer_buffer_length =
			FRAME_SIZE_PER_DESC * FRAMES_PER_DESC;

		for (fx = 0; fx < FRAMES_PER_DESC; fx++) {
			urb->iso_frame_desc[fx].offset =
				FRAME_SIZE_PER_DESC * fx;
			urb->iso_frame_desc[fx].length = FRAME_SIZE_PER_DESC;
		}
	}


	/* Queue the ISO urbs, and resubmit in the completion handler */
	for(i=0; i<NUM_SBUF; ++i) {
		err = usb_submit_urb(cam->sbuf[i].urb, GFP_KERNEL);
		if (err) {
			ERR("usb_submit_urb[%d]() = %d\n", i, err);
			return err;
		}
	}

	return 0;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_start
 *
 *****************************************************************************/
int cpia2_usb_stream_start(struct camera_data *cam, unsigned int alternate)
{
	int ret;
	int old_alt;

	if(cam->streaming)
		return 0;

	if (cam->flush) {
		int i;
		DBG("Flushing buffers\n");
		for(i=0; i<cam->num_frames; ++i) {
			cam->buffers[i].status = FRAME_EMPTY;
			cam->buffers[i].length = 0;
		}
		cam->curbuff = &cam->buffers[0];
		cam->workbuff = cam->curbuff->next;
		cam->flush = false;
	}

	old_alt = cam->params.camera_state.stream_mode;
	cam->params.camera_state.stream_mode = 0;
	ret = cpia2_usb_change_streaming_alternate(cam, alternate);
	if (ret < 0) {
		int ret2;
		ERR("cpia2_usb_change_streaming_alternate() = %d!\n", ret);
		cam->params.camera_state.stream_mode = old_alt;
		ret2 = set_alternate(cam, USBIF_CMDONLY);
		if (ret2 < 0) {
			ERR("cpia2_usb_change_streaming_alternate(%d) =%d has already failed. Then tried to call set_alternate(USBIF_CMDONLY) = %d.\n",
			    alternate, ret, ret2);
		}
	} else {
		cam->frame_count = 0;
		cam->streaming = 1;
		ret = cpia2_usb_stream_resume(cam);
	}
	return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_pause
 *
 *****************************************************************************/
int cpia2_usb_stream_pause(struct camera_data *cam)
{
	int ret = 0;
	if(cam->streaming) {
		free_sbufs(cam);
		ret = set_alternate(cam, USBIF_CMDONLY);
	}
	return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_resume
 *
 *****************************************************************************/
int cpia2_usb_stream_resume(struct camera_data *cam)
{
	int ret = 0;
	if(cam->streaming) {
		cam->first_image_seen = 0;
		ret = set_alternate(cam, cam->params.camera_state.stream_mode);
		if(ret == 0) {
			/* for some reason the user effects need to be set
			   again when starting streaming. */
			cpia2_do_command(cam, CPIA2_CMD_SET_USER_EFFECTS, TRANSFER_WRITE,
					cam->params.vp_params.user_effects);
			ret = submit_urbs(cam);
		}
	}
	return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_stop
 *
 *****************************************************************************/
int cpia2_usb_stream_stop(struct camera_data *cam)
{
	int ret;

	ret = cpia2_usb_stream_pause(cam);
	cam->streaming = 0;
	configure_transfer_mode(cam, 0);
	return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_probe
 *
 *  Probe and initialize.
 *****************************************************************************/
static int cpia2_usb_probe(struct usb_interface *intf,
			   const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct usb_interface_descriptor *interface;
	struct camera_data *cam;
	int ret;

	/* A multi-config CPiA2 camera? */
	if (udev->descriptor.bNumConfigurations != 1)
		return -ENODEV;
	interface = &intf->cur_altsetting->desc;

	/* If we get to this point, we found a CPiA2 camera */
	LOG("CPiA2 USB camera found\n");

	cam = cpia2_init_camera_struct(intf);
	if (cam == NULL)
		return -ENOMEM;

	cam->dev = udev;
	cam->iface = interface->bInterfaceNumber;

	ret = set_alternate(cam, USBIF_CMDONLY);
	if (ret < 0) {
		ERR("%s: usb_set_interface error (ret = %d)\n", __func__, ret);
		goto alt_err;
	}


	if((ret = cpia2_init_camera(cam)) < 0) {
		ERR("%s: failed to initialize cpia2 camera (ret = %d)\n", __func__, ret);
		goto alt_err;
	}
	LOG("  CPiA Version: %d.%02d (%d.%d)\n",
	       cam->params.version.firmware_revision_hi,
	       cam->params.version.firmware_revision_lo,
	       cam->params.version.asic_id,
	       cam->params.version.asic_rev);
	LOG("  CPiA PnP-ID: %04x:%04x:%04x\n",
	       cam->params.pnp_id.vendor,
	       cam->params.pnp_id.product,
	       cam->params.pnp_id.device_revision);
	LOG("  SensorID: %d.(version %d)\n",
	       cam->params.version.sensor_flags,
	       cam->params.version.sensor_rev);

	usb_set_intfdata(intf, cam);

	ret = cpia2_register_camera(cam);
	if (ret < 0) {
		ERR("%s: Failed to register cpia2 camera (ret = %d)\n", __func__, ret);
		goto alt_err;
	}

	return 0;

alt_err:
	cpia2_deinit_camera_struct(cam, intf);
	return ret;
}

/******************************************************************************
 *
 *  cpia2_disconnect
 *
 *****************************************************************************/
static void cpia2_usb_disconnect(struct usb_interface *intf)
{
	struct camera_data *cam = usb_get_intfdata(intf);
	usb_set_intfdata(intf, NULL);

	DBG("Stopping stream\n");
	cpia2_usb_stream_stop(cam);

	mutex_lock(&cam->v4l2_lock);
	DBG("Unregistering camera\n");
	cpia2_unregister_camera(cam);
	v4l2_device_disconnect(&cam->v4l2_dev);
	mutex_unlock(&cam->v4l2_lock);

	if(cam->buffers) {
		DBG("Wakeup waiting processes\n");
		cam->curbuff->status = FRAME_READY;
		cam->curbuff->length = 0;
		wake_up_interruptible(&cam->wq_stream);
	}

	v4l2_device_put(&cam->v4l2_dev);

	LOG("CPiA2 camera disconnected.\n");
}

static int cpia2_usb_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct camera_data *cam = usb_get_intfdata(intf);

	mutex_lock(&cam->v4l2_lock);
	if (cam->streaming) {
		cpia2_usb_stream_stop(cam);
		cam->streaming = 1;
	}
	mutex_unlock(&cam->v4l2_lock);

	dev_info(&intf->dev, "going into suspend..\n");
	return 0;
}

/* Resume device - start device. */
static int cpia2_usb_resume(struct usb_interface *intf)
{
	struct camera_data *cam = usb_get_intfdata(intf);

	mutex_lock(&cam->v4l2_lock);
	v4l2_ctrl_handler_setup(&cam->hdl);
	if (cam->streaming) {
		cam->streaming = 0;
		cpia2_usb_stream_start(cam,
				cam->params.camera_state.stream_mode);
	}
	mutex_unlock(&cam->v4l2_lock);

	dev_info(&intf->dev, "coming out of suspend..\n");
	return 0;
}

/******************************************************************************
 *
 *  usb_cpia2_init
 *
 *****************************************************************************/
int cpia2_usb_init(void)
{
	return usb_register(&cpia2_driver);
}

/******************************************************************************
 *
 *  usb_cpia_cleanup
 *
 *****************************************************************************/
void cpia2_usb_cleanup(void)
{
	schedule_timeout(2 * HZ);
	usb_deregister(&cpia2_driver);
}