Staging: b3dfg: fixups and improvements

- Added support for cable plug/unplug detection.
 - Improvements to error handling.
 - Switch to the pci_* DMA API.
 - Removed set_num_buffers functionality.
 - Locking review.
 - Unconditionally disable transmission when releasing device.
Signed-off-by: Justin Bronder <jsbronder@brontes3d.com>
Cc: Duane Griffin <duaneg@dghda.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/b3dfg/b3dfg.c

@@ -34,52 +34,52 @@
 #include <linux/wait.h>
 #include <linux/mm.h>
 #include <linux/version.h>
-#include <linux/mutex.h>
 
-#include <asm/atomic.h>
 #include <asm/uaccess.h>
 
 /* TODO:
- * locking
  * queue/wait buffer presents filltime results for each frame?
  * counting of dropped frames
  * review endianness
  */
 
-#ifdef DEBUG
-#define dbg(msg...) printk(msg)
-#else
-#define dbg(msg...)
-#endif
+static unsigned int b3dfg_nbuf = 2;
+
+module_param_named(buffer_count, b3dfg_nbuf, uint, 0444);
+
+MODULE_PARM_DESC(buffer_count, "Number of buffers (min 2, default 2)\n");
+
+MODULE_AUTHOR("Daniel Drake <ddrake@brontes3d.com>");
+MODULE_DESCRIPTION("Brontes frame grabber driver");
+MODULE_LICENSE("GPL");
 
 #define DRIVER_NAME "b3dfg"
-#define PFX DRIVER_NAME ": "
 #define B3DFG_MAX_DEVS 4
-#define B3DFG_NR_TRIPLET_BUFFERS 4
-#define B3DFG_NR_FRAME_BUFFERS (B3DFG_NR_TRIPLET_BUFFERS * 3)
 #define B3DFG_FRAMES_PER_BUFFER 3
 
 #define B3DFG_BAR_REGS	0
 #define B3DFG_REGS_LENGTH 0x10000
 
-#define B3DFG_IOC_MAGIC			0xb3 /* dfg :-) */
-#define B3DFG_IOCGFRMSZ			_IOR(B3DFG_IOC_MAGIC, 1, int)
-#define B3DFG_IOCTNUMBUFS		_IO(B3DFG_IOC_MAGIC, 2)
-#define B3DFG_IOCTTRANS			_IO(B3DFG_IOC_MAGIC, 3)
-#define B3DFG_IOCTQUEUEBUF		_IO(B3DFG_IOC_MAGIC, 4)
-#define B3DFG_IOCTPOLLBUF		_IOWR(B3DFG_IOC_MAGIC, 5, struct b3dfg_poll)
-#define B3DFG_IOCTWAITBUF		_IOWR(B3DFG_IOC_MAGIC, 6, struct b3dfg_wait)
-#define B3DFG_IOCGWANDSTAT		_IOR(B3DFG_IOC_MAGIC, 7, int)
+#define B3DFG_IOC_MAGIC		0xb3 /* dfg :-) */
+#define B3DFG_IOCGFRMSZ		_IOR(B3DFG_IOC_MAGIC, 1, int)
+#define B3DFG_IOCTNUMBUFS	_IO(B3DFG_IOC_MAGIC, 2)
+#define B3DFG_IOCTTRANS		_IO(B3DFG_IOC_MAGIC, 3)
+#define B3DFG_IOCTQUEUEBUF	_IO(B3DFG_IOC_MAGIC, 4)
+#define B3DFG_IOCTPOLLBUF	_IOWR(B3DFG_IOC_MAGIC, 5, struct b3dfg_poll)
+#define B3DFG_IOCTWAITBUF	_IOWR(B3DFG_IOC_MAGIC, 6, struct b3dfg_wait)
+#define B3DFG_IOCGWANDSTAT	_IOR(B3DFG_IOC_MAGIC, 7, int)
 
 enum {
 	/* number of 4kb pages per frame */
 	B3D_REG_FRM_SIZE = 0x0,
 
-	/* bit 0: set to enable interrupts */
+	/* bit 0: set to enable interrupts
+	 * bit 1: set to enable cable status change interrupts */
 	B3D_REG_HW_CTRL = 0x4,
 
-	/* bit 0-1 - 1-based ID of next pending frame transfer (0 = nothing pending)
+	/* bit 0-1 - 1-based ID of next pending frame transfer (0 = none)
 	 * bit 2 indicates the previous DMA transfer has completed
+	 * bit 3 indicates wand cable status change
 	 * bit 8:15 - counter of number of discarded triplets */
 	B3D_REG_DMA_STS = 0x8,
 
@@ -110,41 +110,48 @@ enum b3dfg_buffer_state {
 
 struct b3dfg_buffer {
 	unsigned char *frame[B3DFG_FRAMES_PER_BUFFER];
-	u8 state;
 	struct list_head list;
+	u8 state;
 };
 
 struct b3dfg_dev {
+
 	/* no protection needed: all finalized at initialization time */
 	struct pci_dev *pdev;
-    struct cdev chardev;
-    struct class_device *classdev;
+	struct cdev chardev;
+	struct class_device *classdev;
 	void __iomem *regs;
 	unsigned int frame_size;
 
-	/* we want to serialize some ioctl operations */
-	struct mutex ioctl_mutex;
-
-	/* preallocated frame buffers */
-	unsigned char *frame_buffer[B3DFG_NR_FRAME_BUFFERS];
-
-	/* buffers_lock protects num_buffers, buffers, buffer_queue */
+	/*
+	 * Protects buffer state, including buffer_queue, triplet_ready,
+	 * cur_dma_frame_idx & cur_dma_frame_addr.
+	 */
 	spinlock_t buffer_lock;
-	int num_buffers;
 	struct b3dfg_buffer *buffers;
 	struct list_head buffer_queue;
 
-	wait_queue_head_t buffer_waitqueue;
+	/* Last frame in triplet transferred (-1 if none). */
+	int cur_dma_frame_idx;
 
-	atomic_t mapping_count;
+	/* Current frame's address for DMA. */
+	dma_addr_t cur_dma_frame_addr;
 
+	/*
+	 * Protects cstate_tstamp.
+	 * Nests inside buffer_lock.
+	 */
+	spinlock_t cstate_lock;
+	unsigned long cstate_tstamp;
+
+	/*
+	 * Protects triplets_dropped.
+	 * Nests inside buffers_lock.
+	 */
 	spinlock_t triplets_dropped_lock;
 	unsigned int triplets_dropped;
 
-	/* FIXME: we need some locking here. this could be accessed in parallel
-	 * from the queue_buffer ioctl and the interrupt handler. */
-	int cur_dma_frame_idx;
-	dma_addr_t cur_dma_frame_addr;
+	wait_queue_head_t buffer_waitqueue;
 
 	unsigned int transmission_enabled:1;
 	unsigned int triplet_ready:1;
@@ -159,11 +166,13 @@ static const struct pci_device_id b3dfg_ids[] __devinitdata = {
 	{ PCI_DEVICE(0x0b3d, 0x0001) },
 
 	/* FIXME: remove this ID once all boards have been moved to 0xb3d.
-	 * this is Eureka's vendor ID that we borrowed before we bought our own. */
+	 * Eureka's vendor ID that we borrowed before we bought our own. */
 	{ PCI_DEVICE(0x1901, 0x0001) },
 	{ },
 };
 
+MODULE_DEVICE_TABLE(pci, b3dfg_ids);
+
 /***** user-visible types *****/
 
 struct b3dfg_poll {
@@ -191,145 +200,61 @@ static void b3dfg_write32(struct b3dfg_dev *fgdev, u16 reg, u32 value)
 
 /**** buffer management ****/
 
-/* program EC220 for transfer of a specific frame */
-static void setup_frame_transfer(struct b3dfg_dev *fgdev,
-	struct b3dfg_buffer *buf, int frame, int acknowledge)
+/*
+ * Program EC220 for transfer of a specific frame.
+ * Called with buffer_lock held.
+ */
+static int setup_frame_transfer(struct b3dfg_dev *fgdev,
+	struct b3dfg_buffer *buf, int frame)
 {
 	unsigned char *frm_addr;
 	dma_addr_t frm_addr_dma;
-	struct device *dev = &fgdev->pdev->dev;
-	unsigned int frame_size = fgdev->frame_size;
-	unsigned char dma_sts = 0xd;
+	unsigned int frm_size = fgdev->frame_size;
 
 	frm_addr = buf->frame[frame];
-	frm_addr_dma = dma_map_single(dev, frm_addr, frame_size, DMA_FROM_DEVICE);
+	frm_addr_dma = pci_map_single(fgdev->pdev, frm_addr,
+				      frm_size, PCI_DMA_FROMDEVICE);
+	if (pci_dma_mapping_error(frm_addr_dma))
+		return -ENOMEM;
+
 	fgdev->cur_dma_frame_addr = frm_addr_dma;
 	fgdev->cur_dma_frame_idx = frame;
 
 	b3dfg_write32(fgdev, B3D_REG_EC220_DMA_ADDR, cpu_to_le32(frm_addr_dma));
-	b3dfg_write32(fgdev, B3D_REG_EC220_TRF_SIZE, cpu_to_le32(frame_size >> 2));
-
-	if (likely(acknowledge))
-		dma_sts |= 0x2;
+	b3dfg_write32(fgdev, B3D_REG_EC220_TRF_SIZE, cpu_to_le32(frm_size >> 2));
 	b3dfg_write32(fgdev, B3D_REG_EC220_DMA_STS, 0xf);
-}
-
-/* retrieve a buffer pointer from a buffer index. also checks that the
- * requested buffer actually exists. buffer_lock should be held by caller */
-static inline struct b3dfg_buffer *buffer_from_idx(struct b3dfg_dev *fgdev,
-	int idx)
-{
-	if (unlikely(idx >= fgdev->num_buffers))
-		return NULL;
-	return &fgdev->buffers[idx];
-}
 
-/* caller should hold buffer lock */
-static void free_all_buffers(struct b3dfg_dev *fgdev)
-{
-	kfree(fgdev->buffers);
-	fgdev->buffers = NULL;
-	fgdev->num_buffers = 0;
+	return 0;
 }
 
+/* Caller should hold buffer lock */
 static void dequeue_all_buffers(struct b3dfg_dev *fgdev)
 {
 	int i;
-	for (i = 0; i < fgdev->num_buffers; i++) {
+	for (i = 0; i < b3dfg_nbuf; i++) {
 		struct b3dfg_buffer *buf = &fgdev->buffers[i];
 		buf->state = B3DFG_BUFFER_POLLED;
 		list_del_init(&buf->list);
 	}
 }
 
-/* initialize a buffer: allocate its frames, set default values */
-static void init_buffer(struct b3dfg_dev *fgdev, struct b3dfg_buffer *buf,
-	int idx)
-{
-	unsigned int addr_offset = idx * B3DFG_FRAMES_PER_BUFFER;
-	int i;
-
-	memset(buf, 0, sizeof(struct b3dfg_buffer));
-	for (i = 0; i < B3DFG_FRAMES_PER_BUFFER; i++)
-		buf->frame[i] = fgdev->frame_buffer[addr_offset + i];
-
-	INIT_LIST_HEAD(&buf->list);
-}
-
-/* adjust the number of buffers, growing or shrinking the pool appropriately. */
-static int set_num_buffers(struct b3dfg_dev *fgdev, int num_buffers)
-{
-	int i;
-	struct b3dfg_buffer *buffers;
-	unsigned long flags;
-
-	printk(KERN_INFO PFX "set %d buffers\n", num_buffers);
-	if (fgdev->transmission_enabled) {
-		printk(KERN_ERR PFX
-			"cannot set buffer count while transmission is enabled\n");
-		return -EBUSY;
-	}
-
-	if (atomic_read(&fgdev->mapping_count) > 0) {
-		printk(KERN_ERR PFX
-			"cannot set buffer count while memory mappings are active\n");
-		return -EBUSY;
-	}
-
-	if (num_buffers > B3DFG_NR_TRIPLET_BUFFERS) {
-		printk(KERN_ERR PFX "limited to %d triplet buffers\n",
-			B3DFG_NR_TRIPLET_BUFFERS);
-		return -E2BIG;
-	}
-
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	if (num_buffers == fgdev->num_buffers) {
-		spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-		return 0;
-	}
-
-	/* free all buffers then allocate new ones */
-	dequeue_all_buffers(fgdev);
-	free_all_buffers(fgdev);
-
-	/* must unlock to allocate GFP_KERNEL memory */
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-
-	if (num_buffers == 0)
-		return 0;
-
-	buffers = kmalloc(num_buffers * sizeof(struct b3dfg_buffer),
-		GFP_KERNEL);
-	if (!buffers)
-		return -ENOMEM;
-
-	for (i = 0; i < num_buffers; i++)
-		init_buffer(fgdev, &buffers[i], i);
-
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	fgdev->buffers = buffers;
-	fgdev->num_buffers = num_buffers;
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-
-	return 0;
-}
-
 /* queue a buffer to receive data */
 static int queue_buffer(struct b3dfg_dev *fgdev, int bufidx)
 {
+	struct device *dev = &fgdev->pdev->dev;
 	struct b3dfg_buffer *buf;
 	unsigned long flags;
 	int r = 0;
 
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	buf = buffer_from_idx(fgdev, bufidx);
-	if (unlikely(!buf)) {
+	if (bufidx < 0 || bufidx >= b3dfg_nbuf) {
 		r = -ENOENT;
 		goto out;
 	}
+	buf = &fgdev->buffers[bufidx];
 
 	if (unlikely(buf->state == B3DFG_BUFFER_PENDING)) {
-		printk(KERN_ERR PFX "buffer %d is already queued", bufidx);
+		dev_dbg(dev, "buffer %d is already queued\n", bufidx);
 		r = -EINVAL;
 		goto out;
 	}
@@ -338,9 +263,11 @@ static int queue_buffer(struct b3dfg_dev *fgdev, int bufidx)
 	list_add_tail(&buf->list, &fgdev->buffer_queue);
 
 	if (fgdev->transmission_enabled && fgdev->triplet_ready) {
-		dbg("triplet is ready, so pushing immediately\n");
+		dev_dbg(dev, "triplet is ready, pushing immediately\n");
 		fgdev->triplet_ready = 0;
-		setup_frame_transfer(fgdev, buf, 0, 0);
+		r = setup_frame_transfer(fgdev, buf, 0);
+		if (r)
+			dev_err(dev, "unable to map DMA buffer\n");
 	}
 
 out:
@@ -352,139 +279,159 @@ static int queue_buffer(struct b3dfg_dev *fgdev, int bufidx)
  * 0 otherwise */
 static int poll_buffer(struct b3dfg_dev *fgdev, void __user *arg)
 {
+	struct device *dev = &fgdev->pdev->dev;
 	struct b3dfg_poll p;
 	struct b3dfg_buffer *buf;
 	unsigned long flags;
 	int r = 1;
+	int arg_out = 0;
 
 	if (copy_from_user(&p, arg, sizeof(p)))
 		return -EFAULT;
 
 	if (unlikely(!fgdev->transmission_enabled)) {
-		printk(KERN_ERR PFX
-			"cannot poll buffers when transmission is disabled\n");
+		dev_dbg(dev, "cannot poll, transmission disabled\n");
 		return -EINVAL;
 	}
 
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	buf = buffer_from_idx(fgdev, p.buffer_idx);
-	if (unlikely(!buf)) {
-		r = -ENOENT;
-		goto out;
-	}
+	if (p.buffer_idx < 0 || p.buffer_idx >= b3dfg_nbuf)
+		return -ENOENT;
 
-	if (buf->state != B3DFG_BUFFER_POPULATED) {
-		r = 0;
-		goto out;
-	}
+	buf = &fgdev->buffers[p.buffer_idx];
+
+	spin_lock_irqsave(&fgdev->buffer_lock, flags);
 
 	if (likely(buf->state == B3DFG_BUFFER_POPULATED)) {
+		arg_out = 1;
 		buf->state = B3DFG_BUFFER_POLLED;
+
+		/* IRQs already disabled by spin_lock_irqsave above. */
 		spin_lock(&fgdev->triplets_dropped_lock);
 		p.triplets_dropped = fgdev->triplets_dropped;
 		fgdev->triplets_dropped = 0;
 		spin_unlock(&fgdev->triplets_dropped_lock);
-		if (copy_to_user(arg, &p, sizeof(p)))
-			r = -EFAULT;
+	} else {
+		r = 0;
 	}
 
-out:
 	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+	if (arg_out && copy_to_user(arg, &p, sizeof(p)))
+		r = -EFAULT;
+
 	return r;
 }
 
-static u8 buffer_state(struct b3dfg_dev *fgdev, struct b3dfg_buffer *buf)
+static unsigned long get_cstate_change(struct b3dfg_dev *fgdev)
+{
+	unsigned long flags, when;
+
+	spin_lock_irqsave(&fgdev->cstate_lock, flags);
+	when = fgdev->cstate_tstamp;
+	spin_unlock_irqrestore(&fgdev->cstate_lock, flags);
+	return when;
+}
+
+static int is_event_ready(struct b3dfg_dev *fgdev, struct b3dfg_buffer *buf,
+			  unsigned long when)
 {
+	int result;
 	unsigned long flags;
-	u8 state;
 
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	state = buf->state;
+	spin_lock(&fgdev->cstate_lock);
+	result = (!fgdev->transmission_enabled ||
+		  buf->state == B3DFG_BUFFER_POPULATED ||
+		  when != fgdev->cstate_tstamp);
+	spin_unlock(&fgdev->cstate_lock);
 	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-	return state;
+
+	return result;
 }
 
 /* sleep until a specific buffer becomes populated */
 static int wait_buffer(struct b3dfg_dev *fgdev, void __user *arg)
 {
+	struct device *dev = &fgdev->pdev->dev;
 	struct b3dfg_wait w;
 	struct b3dfg_buffer *buf;
-	unsigned long flags;
+	unsigned long flags, when;
 	int r;
 
 	if (copy_from_user(&w, arg, sizeof(w)))
 		return -EFAULT;
 
-	if (unlikely(!fgdev->transmission_enabled)) {
-		printk(KERN_ERR PFX
-			"cannot wait on buffers when transmission is disabled\n");
+	if (!fgdev->transmission_enabled) {
+		dev_dbg(dev, "cannot wait, transmission disabled\n");
 		return -EINVAL;
 	}
 
+	if (w.buffer_idx < 0 || w.buffer_idx >= b3dfg_nbuf)
+		return -ENOENT;
+
+	buf = &fgdev->buffers[w.buffer_idx];
+
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	buf = buffer_from_idx(fgdev, w.buffer_idx);
-	if (unlikely(!buf)) {
-		r = -ENOENT;
-		goto out;
-	}
 
 	if (buf->state == B3DFG_BUFFER_POPULATED) {
-		r = 0;
+		r = w.timeout;
 		goto out_triplets_dropped;
 	}
 
 	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-	/* FIXME: what prevents the buffer going away at this time? */
 
+	when = get_cstate_change(fgdev);
 	if (w.timeout > 0) {
 		r = wait_event_interruptible_timeout(fgdev->buffer_waitqueue,
-			buffer_state(fgdev, buf) == B3DFG_BUFFER_POPULATED,
+			is_event_ready(fgdev, buf, when),
 			(w.timeout * HZ) / 1000);
+
 		if (unlikely(r < 0))
-			return r;
-		else if (unlikely(buffer_state(fgdev, buf)
-				!= B3DFG_BUFFER_POPULATED))
-			return -ETIMEDOUT;
+			goto out;
+
 		w.timeout = r * 1000 / HZ;
 	} else {
 		r = wait_event_interruptible(fgdev->buffer_waitqueue,
-			buffer_state(fgdev, buf) == B3DFG_BUFFER_POPULATED);
-		if (unlikely(r))
-			return -ERESTARTSYS;
+			is_event_ready(fgdev, buf, when));
+
+		if (unlikely(r)) {
+			r = -ERESTARTSYS;
+			goto out;
+		}
+	}
+
+	/* TODO: Inform the user via field(s) in w? */
+	if (!fgdev->transmission_enabled || when != get_cstate_change(fgdev)) {
+		r = -EINVAL;
+		goto out;
 	}
 
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	/* FIXME: rediscover buffer? it might have changed during the unlocked
-	 * time */
+
+	if (buf->state != B3DFG_BUFFER_POPULATED) {
+		r = -ETIMEDOUT;
+		goto out_unlock;
+	}
+
 	buf->state = B3DFG_BUFFER_POLLED;
 
 out_triplets_dropped:
+
+	/* IRQs already disabled by spin_lock_irqsave above. */
 	spin_lock(&fgdev->triplets_dropped_lock);
 	w.triplets_dropped = fgdev->triplets_dropped;
 	fgdev->triplets_dropped = 0;
 	spin_unlock(&fgdev->triplets_dropped_lock);
+
+out_unlock:
+	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
 	if (copy_to_user(arg, &w, sizeof(w)))
 		r = -EFAULT;
 out:
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
 	return r;
 }
 
-/**** virtual memory mapping ****/
-
-static void b3dfg_vma_open(struct vm_area_struct *vma)
-{
-	struct b3dfg_dev *fgdev = vma->vm_file->private_data;
-	atomic_inc(&fgdev->mapping_count);
-}
-
-static void b3dfg_vma_close(struct vm_area_struct *vma)
-{
-	struct b3dfg_dev *fgdev = vma->vm_file->private_data;
-	atomic_dec(&fgdev->mapping_count);
-}
-
-/* page fault handler */
+/* mmap page fault handler */
 static unsigned long b3dfg_vma_nopfn(struct vm_area_struct *vma,
 	unsigned long address)
 {
@@ -492,7 +439,6 @@ static unsigned long b3dfg_vma_nopfn(struct vm_area_struct *vma,
 	unsigned long off = address - vma->vm_start;
 	unsigned int frame_size = fgdev->frame_size;
 	unsigned int buf_size = frame_size * B3DFG_FRAMES_PER_BUFFER;
-	unsigned long flags;
 	unsigned char *addr;
 
 	/* determine which buffer the offset lies within */
@@ -505,29 +451,24 @@ static unsigned long b3dfg_vma_nopfn(struct vm_area_struct *vma,
 	/* and the offset into the frame */
 	unsigned int frm_off = buf_off % frame_size;
 
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	if (unlikely(buf_idx > fgdev->num_buffers)) {
-		spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+	if (unlikely(buf_idx >= b3dfg_nbuf))
 		return NOPFN_SIGBUS;
-	}
 
 	addr = fgdev->buffers[buf_idx].frame[frm_idx] + frm_off;
 	vm_insert_pfn(vma, vma->vm_start + off,
-		virt_to_phys(addr) >> PAGE_SHIFT);
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+		      virt_to_phys(addr) >> PAGE_SHIFT);
+
 	return NOPFN_REFAULT;
 }
 
 static struct vm_operations_struct b3dfg_vm_ops = {
-	.open = b3dfg_vma_open,
-	.close = b3dfg_vma_close,
 	.nopfn = b3dfg_vma_nopfn,
 };
 
 static int get_wand_status(struct b3dfg_dev *fgdev, int __user *arg)
 {
 	u32 wndstat = b3dfg_read32(fgdev, B3D_REG_WAND_STS);
-	dbg("wand status %x\n", wndstat);
+	dev_dbg(&fgdev->pdev->dev, "wand status %x\n", wndstat);
 	return __put_user(wndstat & 0x1, arg);
 }
 
@@ -535,47 +476,63 @@ static int enable_transmission(struct b3dfg_dev *fgdev)
 {
 	u16 command;
 	unsigned long flags;
+	struct device *dev = &fgdev->pdev->dev;
+
+	dev_dbg(dev, "enable transmission\n");
 
-	printk(KERN_INFO PFX "enable transmission\n");
+	/* check the cable is plugged in. */
+	if (!b3dfg_read32(fgdev, B3D_REG_WAND_STS)) {
+		dev_dbg(dev, "cannot start transmission without wand\n");
+		return -EINVAL;
+	}
 
-	/* check we're a bus master */
+	/*
+	 * Check we're a bus master.
+	 * TODO: I think we can remove this having added the pci_set_master call
+	 */
 	pci_read_config_word(fgdev->pdev, PCI_COMMAND, &command);
 	if (!(command & PCI_COMMAND_MASTER)) {
-		printk(KERN_ERR PFX "not a bus master, force-enabling\n");
-		/* FIXME: why did we lose it in the first place? */
+		dev_err(dev, "not a bus master, force-enabling\n");
 		pci_write_config_word(fgdev->pdev, PCI_COMMAND,
 			command | PCI_COMMAND_MASTER);
 	}
 
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	if (fgdev->num_buffers == 0) {
+
+	/* Handle racing enable_transmission calls. */
+	if (fgdev->transmission_enabled) {
 		spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-		printk(KERN_ERR PFX "cannot start transmission to 0 buffers\n");
-		return -EINVAL;
+		goto out;
 	}
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
 
-	spin_lock_irqsave(&fgdev->triplets_dropped_lock, flags);
+	spin_lock(&fgdev->triplets_dropped_lock);
 	fgdev->triplets_dropped = 0;
-	spin_unlock_irqrestore(&fgdev->triplets_dropped_lock, flags);
+	spin_unlock(&fgdev->triplets_dropped_lock);
 
 	fgdev->triplet_ready = 0;
-	fgdev->transmission_enabled = 1;
 	fgdev->cur_dma_frame_idx = -1;
-	b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 1);
+	fgdev->transmission_enabled = 1;
+
+	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+	/* Enable DMA and cable status interrupts. */
+	b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0x03);
+
+out:
 	return 0;
 }
 
 static void disable_transmission(struct b3dfg_dev *fgdev)
 {
+	struct device *dev = &fgdev->pdev->dev;
 	unsigned long flags;
 	u32 tmp;
 
-	printk(KERN_INFO PFX "disable transmission\n");
+	dev_dbg(dev, "disable transmission\n");
 
 	/* guarantee that no more interrupts will be serviced */
+	spin_lock_irqsave(&fgdev->buffer_lock, flags);
 	fgdev->transmission_enabled = 0;
-	synchronize_irq(fgdev->pdev->irq);
 
 	b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0);
 
@@ -583,130 +540,238 @@ static void disable_transmission(struct b3dfg_dev *fgdev)
 	 * hitting ctrl+c and seeing this message is useful for determining
 	 * the state of the board. */
 	tmp = b3dfg_read32(fgdev, B3D_REG_DMA_STS);
-	dbg("brontes DMA_STS reads %x after TX stopped\n", tmp);
+	dev_dbg(dev, "DMA_STS reads %x after TX stopped\n", tmp);
 
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
 	dequeue_all_buffers(fgdev);
 	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
+
+	wake_up_interruptible(&fgdev->buffer_waitqueue);
 }
 
 static int set_transmission(struct b3dfg_dev *fgdev, int enabled)
 {
+	int res = 0;
+
 	if (enabled && !fgdev->transmission_enabled)
-		return enable_transmission(fgdev);
+		res = enable_transmission(fgdev);
 	else if (!enabled && fgdev->transmission_enabled)
 		disable_transmission(fgdev);
-	return 0;
+
+	return res;
+}
+
+/* Called in interrupt context. */
+static void handle_cstate_unplug(struct b3dfg_dev *fgdev)
+{
+	/* Disable all interrupts. */
+	b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0);
+
+	/* Stop transmission. */
+	spin_lock(&fgdev->buffer_lock);
+	fgdev->transmission_enabled = 0;
+
+	fgdev->cur_dma_frame_idx = -1;
+	fgdev->triplet_ready = 0;
+	if (fgdev->cur_dma_frame_addr) {
+		pci_unmap_single(fgdev->pdev, fgdev->cur_dma_frame_addr,
+				 fgdev->frame_size, PCI_DMA_FROMDEVICE);
+		fgdev->cur_dma_frame_addr = 0;
+	}
+	dequeue_all_buffers(fgdev);
+	spin_unlock(&fgdev->buffer_lock);
+}
+
+/* Called in interrupt context. */
+static void handle_cstate_change(struct b3dfg_dev *fgdev)
+{
+	u32 cstate = b3dfg_read32(fgdev, B3D_REG_WAND_STS);
+	unsigned long when;
+	struct device *dev = &fgdev->pdev->dev;
+
+	dev_dbg(dev, "cable state change: %u\n", cstate);
+
+	/*
+	 * When the wand is unplugged we reset our state. The hardware will
+	 * have done the same internally.
+	 *
+	 * Note we should never see a cable *plugged* event, as interrupts
+	 * should only be enabled when transmitting, which requires the cable
+	 * to be plugged. If we do see one it probably means the cable has been
+	 * unplugged and re-plugged very rapidly. Possibly because it has a
+	 * broken wire and is momentarily losing contact.
+	 *
+	 * TODO: At the moment if you plug in the cable then enable transmission
+	 *       the hardware will raise a couple of spurious interrupts, so
+	 *       just ignore them for now.
+	 *
+	 *      Once the hardware is fixed we should complain and treat it as an
+	 *      unplug. Or at least track how frequently it is happening and do
+	 *      so if too many come in.
+	 */
+	if (cstate) {
+		dev_warn(dev, "ignoring unexpected plug event\n");
+		return;
+	}
+	handle_cstate_unplug(fgdev);
+
+	/*
+	 * Record cable state change timestamp & wake anyone waiting
+	 * on a cable state change. Be paranoid about ensuring events
+	 * are not missed if we somehow get two interrupts in a jiffy.
+	 */
+	spin_lock(&fgdev->cstate_lock);
+	when = jiffies_64;
+	if (when <= fgdev->cstate_tstamp)
+		when = fgdev->cstate_tstamp + 1;
+	fgdev->cstate_tstamp = when;
+	wake_up_interruptible(&fgdev->buffer_waitqueue);
+	spin_unlock(&fgdev->cstate_lock);
+}
+
+/* Called with buffer_lock held. */
+static void transfer_complete(struct b3dfg_dev *fgdev)
+{
+	struct b3dfg_buffer *buf;
+	struct device *dev = &fgdev->pdev->dev;
+
+	pci_unmap_single(fgdev->pdev, fgdev->cur_dma_frame_addr,
+			 fgdev->frame_size, PCI_DMA_FROMDEVICE);
+	fgdev->cur_dma_frame_addr = 0;
+
+	buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
+	if (buf) {
+		dev_dbg(dev, "handle frame completion\n");
+		if (fgdev->cur_dma_frame_idx == B3DFG_FRAMES_PER_BUFFER - 1) {
+
+			/* last frame of that triplet completed */
+			dev_dbg(dev, "triplet completed\n");
+			buf->state = B3DFG_BUFFER_POPULATED;
+			list_del_init(&buf->list);
+			wake_up_interruptible(&fgdev->buffer_waitqueue);
+		}
+	} else {
+		dev_err(dev, "got frame but no buffer!\n");
+	}
+}
+
+/*
+ * Called with buffer_lock held.
+ *
+ * Note that idx is the (1-based) *next* frame to be transferred, while
+ * cur_dma_frame_idx is the (0-based) *last* frame to have been transferred (or
+ * -1 if none). Thus there should be a difference of 2 between them.
+ */
+static bool setup_next_frame_transfer(struct b3dfg_dev *fgdev, int idx)
+{
+	struct b3dfg_buffer *buf;
+	struct device *dev = &fgdev->pdev->dev;
+	bool need_ack = 1;
+
+	dev_dbg(dev, "program DMA transfer for next frame: %d\n", idx);
+
+	buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
+	if (buf) {
+		if (idx == fgdev->cur_dma_frame_idx + 2) {
+			if (setup_frame_transfer(fgdev, buf, idx - 1))
+				dev_err(dev, "unable to map DMA buffer\n");
+			need_ack = 0;
+		} else {
+			dev_err(dev, "frame mismatch, got %d, expected %d\n",
+				idx, fgdev->cur_dma_frame_idx + 2);
+
+			/* FIXME: handle dropped triplets here */
+		}
+	} else {
+		dev_err(dev, "cannot setup DMA, no buffer\n");
+	}
+
+	return need_ack;
 }
 
 static irqreturn_t b3dfg_intr(int irq, void *dev_id)
 {
 	struct b3dfg_dev *fgdev = dev_id;
-	struct device *dev;
-	struct b3dfg_buffer *buf = NULL;
-	unsigned int frame_size;
+	struct device *dev = &fgdev->pdev->dev;
 	u32 sts;
 	u8 dropped;
-	int next_trf;
-	int need_ack = 1;
+	bool need_ack = 1;
+	irqreturn_t res = IRQ_HANDLED;
 
-	if (unlikely(!fgdev->transmission_enabled)) {
-		printk("ignore interrupt, TX disabled\n");
-		/* FIXME should return IRQ_NONE when we are stable */
+	sts = b3dfg_read32(fgdev, B3D_REG_DMA_STS);
+	if (unlikely(sts == 0)) {
+		dev_warn(dev, "ignore interrupt, DMA status is 0\n");
+		res = IRQ_NONE;
 		goto out;
 	}
 
-	sts = b3dfg_read32(fgdev, B3D_REG_DMA_STS);
-	if (unlikely(sts == 0)) {
-		printk("ignore interrupt, brontes DMA status is 0\n");
-		/* FIXME should return IRQ_NONE when we are stable */
+	if (unlikely(!fgdev->transmission_enabled)) {
+		dev_warn(dev, "ignore interrupt, TX disabled\n");
+		res = IRQ_HANDLED;
 		goto out;
 	}
 
+	/* Handle dropped frames, as reported by the hardware. */
 	dropped = (sts >> 8) & 0xff;
-	dbg(KERN_INFO PFX "got intr, brontes DMASTS=%08x (dropped=%d comp=%d next_trf=%d)\n", sts, dropped, !!(sts & 0x4), sts & 0x3);
-
+	dev_dbg(dev, "intr: DMA_STS=%08x (drop=%d comp=%d next=%d)\n",
+		sts, dropped, !!(sts & 0x4), sts & 0x3);
 	if (unlikely(dropped > 0)) {
 		spin_lock(&fgdev->triplets_dropped_lock);
 		fgdev->triplets_dropped += dropped;
 		spin_unlock(&fgdev->triplets_dropped_lock);
 	}
 
-	dev = &fgdev->pdev->dev;
-	frame_size = fgdev->frame_size;
+	/* Handle a cable state change (i.e. the wand being unplugged). */
+	if (sts & 0x08) {
+		handle_cstate_change(fgdev);
+		goto out;
+	}
 
 	spin_lock(&fgdev->buffer_lock);
 	if (unlikely(list_empty(&fgdev->buffer_queue))) {
+
 		/* FIXME need more sanity checking here */
-		dbg("driver has no buffer ready --> cannot program any more transfers\n");
+		dev_info(dev, "buffer not ready for next transfer\n");
 		fgdev->triplet_ready = 1;
 		goto out_unlock;
 	}
 
-	next_trf = sts & 0x3;
-
+	/* Has a frame transfer been completed? */
 	if (sts & 0x4) {
-		u32 tmp;
+		u32 dma_status = b3dfg_read32(fgdev, B3D_REG_EC220_DMA_STS);
+
+		/* Check for DMA errors reported by the hardware. */
+		if (unlikely(dma_status & 0x1)) {
+			dev_err(dev, "EC220 error: %08x\n", dma_status);
 
-		tmp = b3dfg_read32(fgdev, B3D_REG_EC220_DMA_STS);
-		/* last DMA completed */
-		if (unlikely(tmp & 0x1)) {
-			printk(KERN_ERR PFX "EC220 reports error (%08x)\n", tmp);
 			/* FIXME flesh out error handling */
 			goto out_unlock;
 		}
+
+		/* Sanity check, we should have a frame index at this point. */
 		if (unlikely(fgdev->cur_dma_frame_idx == -1)) {
-			printk("ERROR completed but no last idx?\n");
+			dev_err(dev, "completed but no last idx?\n");
+
 			/* FIXME flesh out error handling */
 			goto out_unlock;
 		}
-		dma_unmap_single(dev, fgdev->cur_dma_frame_addr, frame_size,
-			DMA_FROM_DEVICE);
-
-		buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
-		if (likely(buf)) {
-			dbg("handle frame completion\n");
-			if (fgdev->cur_dma_frame_idx == B3DFG_FRAMES_PER_BUFFER - 1) {
-				/* last frame of that triplet completed */
-				dbg("triplet completed\n");
-				buf->state = B3DFG_BUFFER_POPULATED;
-				list_del_init(&buf->list);
-				wake_up_interruptible(&fgdev->buffer_waitqueue);
-			}
-		} else {
-			printk("got frame but no buffer!\n");
-		}
+
+		transfer_complete(fgdev);
 	}
 
-	if (next_trf) {
-		next_trf--;
-
-		buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
-		dbg("program DMA transfer for frame %d\n", next_trf + 1);
-		if (likely(buf)) {
-			if (next_trf != fgdev->cur_dma_frame_idx + 1) {
-				printk("ERROR mismatch, next_trf %d vs cur_dma_frame_idx %d\n",
-					next_trf, fgdev->cur_dma_frame_idx);
-				/* FIXME this is where we should handle dropped triplets */
-				goto out_unlock;
-			}
-			setup_frame_transfer(fgdev, buf, next_trf, 1);
-			need_ack = 0;
-		} else {
-			printk("cannot setup next DMA due to no buffer\n");
-		}
-	} else {
+	/* Is there another frame transfer pending? */
+	if (sts & 0x3)
+		need_ack = setup_next_frame_transfer(fgdev, sts & 0x3);
+	else
 		fgdev->cur_dma_frame_idx = -1;
-	}
 
 out_unlock:
 	spin_unlock(&fgdev->buffer_lock);
 out:
 	if (need_ack) {
-		dbg("acknowledging interrupt\n");
+		dev_dbg(dev, "acknowledging interrupt\n");
 		b3dfg_write32(fgdev, B3D_REG_EC220_DMA_STS, 0x0b);
 	}
-	return IRQ_HANDLED;
+	return res;
 }
 
 static int b3dfg_open(struct inode *inode, struct file *filp)
@@ -714,7 +779,7 @@ static int b3dfg_open(struct inode *inode, struct file *filp)
 	struct b3dfg_dev *fgdev =
 		container_of(inode->i_cdev, struct b3dfg_dev, chardev);
 
-	printk(KERN_INFO PFX "open\n");
+	dev_dbg(&fgdev->pdev->dev, "open\n");
 	filp->private_data = fgdev;
 	return 0;
 }
@@ -722,18 +787,14 @@ static int b3dfg_open(struct inode *inode, struct file *filp)
 static int b3dfg_release(struct inode *inode, struct file *filp)
 {
 	struct b3dfg_dev *fgdev = filp->private_data;
-	printk(KERN_INFO PFX "release\n");
-	set_transmission(fgdev, 0);
-
-	/* no buffer locking needed, this is serialized */
-	dequeue_all_buffers(fgdev);
-	return set_num_buffers(fgdev, 0);
+	dev_dbg(&fgdev->pdev->dev, "release\n");
+	disable_transmission(fgdev);
+	return 0;
 }
 
 static long b3dfg_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct b3dfg_dev *fgdev = filp->private_data;
-	int r;
 
 	switch (cmd) {
 	case B3DFG_IOCGFRMSZ:
@@ -741,15 +802,11 @@ static long b3dfg_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case B3DFG_IOCGWANDSTAT:
 		return get_wand_status(fgdev, (int __user *) arg);
 	case B3DFG_IOCTNUMBUFS:
-		mutex_lock(&fgdev->ioctl_mutex);
-		r = set_num_buffers(fgdev, (int) arg);
-		mutex_unlock(&fgdev->ioctl_mutex);
-		return r;
+
+		/* TODO: Remove once userspace stops using this. */
+		return 0;
 	case B3DFG_IOCTTRANS:
-		mutex_lock(&fgdev->ioctl_mutex);
-		r = set_transmission(fgdev, (int) arg);
-		mutex_unlock(&fgdev->ioctl_mutex);
-		return r;
+		return set_transmission(fgdev, (int) arg);
 	case B3DFG_IOCTQUEUEBUF:
 		return queue_buffer(fgdev, (int) arg);
 	case B3DFG_IOCTPOLLBUF:
@@ -757,7 +814,7 @@ static long b3dfg_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case B3DFG_IOCTWAITBUF:
 		return wait_buffer(fgdev, (void __user *) arg);
 	default:
-		printk(KERN_ERR PFX "unrecognised ioctl %x\n", cmd);
+		dev_dbg(&fgdev->pdev->dev, "unrecognised ioctl %x\n", cmd);
 		return -EINVAL;
 	}
 }
@@ -765,32 +822,26 @@ static long b3dfg_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 static unsigned int b3dfg_poll(struct file *filp, poll_table *poll_table)
 {
 	struct b3dfg_dev *fgdev = filp->private_data;
-	unsigned long flags;
+	unsigned long flags, when;
 	int i;
 	int r = 0;
 
-	/* don't let the user mess with buffer allocations etc. while polling */
-	mutex_lock(&fgdev->ioctl_mutex);
-
-	if (unlikely(!fgdev->transmission_enabled)) {
-		printk(KERN_ERR PFX "cannot poll() when transmission is disabled\n");
-		r = POLLERR;
-		goto out;
-	}
-
+	when = get_cstate_change(fgdev);
 	poll_wait(filp, &fgdev->buffer_waitqueue, poll_table);
+
 	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	for (i = 0; i < fgdev->num_buffers; i++) {
+	for (i = 0; i < b3dfg_nbuf; i++) {
 		if (fgdev->buffers[i].state == B3DFG_BUFFER_POPULATED) {
 			r = POLLIN | POLLRDNORM;
-			goto out_buffer_unlock;
+			break;
 		}
 	}
-
-out_buffer_unlock:
 	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-out:
-	mutex_unlock(&fgdev->ioctl_mutex);
+
+	/* TODO: Confirm this is how we want to communicate the change. */
+	if (!fgdev->transmission_enabled || when != get_cstate_change(fgdev))
+		r = POLLERR;
+
 	return r;
 }
 
@@ -799,35 +850,18 @@ static int b3dfg_mmap(struct file *filp, struct vm_area_struct *vma)
 	struct b3dfg_dev *fgdev = filp->private_data;
 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 	unsigned long vsize = vma->vm_end - vma->vm_start;
-	unsigned long bufdatalen;
-	unsigned long psize;
-	unsigned long flags;
+	unsigned long bufdatalen = b3dfg_nbuf * fgdev->frame_size * 3;
+	unsigned long psize = bufdatalen - offset;
 	int r = 0;
 
-	/* don't let user mess with buffer allocations during mmap */
-	mutex_lock(&fgdev->ioctl_mutex);
-
-	spin_lock_irqsave(&fgdev->buffer_lock, flags);
-	bufdatalen = fgdev->num_buffers * fgdev->frame_size * 3;
-	psize = bufdatalen - offset;
-
-	if (fgdev->num_buffers == 0) {
-		spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-		r = -ENOENT;
-		goto out;
-	}
-	spin_unlock_irqrestore(&fgdev->buffer_lock, flags);
-	if (vsize > psize) {
+	if (vsize <= psize) {
+		vma->vm_flags |= VM_IO | VM_RESERVED | VM_CAN_NONLINEAR |
+				 VM_PFNMAP;
+		vma->vm_ops = &b3dfg_vm_ops;
+	} else {
 		r = -EINVAL;
-		goto out;
 	}
 
-	vma->vm_flags |= VM_IO | VM_RESERVED | VM_CAN_NONLINEAR | VM_PFNMAP;
-	vma->vm_ops = &b3dfg_vm_ops;
-	b3dfg_vma_open(vma);
-
-out:
-	mutex_unlock(&fgdev->ioctl_mutex);
 	return r;
 }
 
@@ -842,43 +876,55 @@ static struct file_operations b3dfg_fops = {
 
 static void free_all_frame_buffers(struct b3dfg_dev *fgdev)
 {
-	int i;
-	for (i = 0; i < B3DFG_NR_FRAME_BUFFERS; i++)
-		kfree(fgdev->frame_buffer[i]);
+	int i, j;
+	for (i = 0; i < b3dfg_nbuf; i++)
+		for (j = 0; j < B3DFG_FRAMES_PER_BUFFER; j++)
+			kfree(fgdev->buffers[i].frame[j]);
+	kfree(fgdev->buffers);
 }
 
 /* initialize device and any data structures. called before any interrupts
  * are enabled. */
 static int b3dfg_init_dev(struct b3dfg_dev *fgdev)
 {
-	int i;
+	int i, j;
 	u32 frm_size = b3dfg_read32(fgdev, B3D_REG_FRM_SIZE);
 
-	/* disable interrupts. in abnormal circumstances (e.g. after a crash) the
-	 * board may still be transmitting from the previous session. if we ensure
-	 * that interrupts are disabled before we later enable them, we are sure
-	 * to capture a triplet from the start, rather than starting from frame
-	 * 2 or 3. disabling interrupts causes the FG to throw away all buffered
-	 * data and stop buffering more until interrupts are enabled again. */
+	/* Disable interrupts. In abnormal circumstances (e.g. after a crash)
+	 * the board may still be transmitting from the previous session. If we
+	 * ensure that interrupts are disabled before we later enable them, we
+	 * are sure to capture a triplet from the start, rather than starting
+	 * from frame 2 or 3. Disabling interrupts causes the FG to throw away
+	 * all buffered data and stop buffering more until interrupts are
+	 * enabled again.
+	 */
 	b3dfg_write32(fgdev, B3D_REG_HW_CTRL, 0);
 
 	fgdev->frame_size = frm_size * 4096;
-	for (i = 0; i < B3DFG_NR_FRAME_BUFFERS; i++) {
-		fgdev->frame_buffer[i] = kmalloc(fgdev->frame_size, GFP_KERNEL);
-		if (!fgdev->frame_buffer[i])
-			goto err_no_mem;
+	fgdev->buffers = kzalloc(sizeof(struct b3dfg_buffer) * b3dfg_nbuf,
+				 GFP_KERNEL);
+	if (!fgdev->buffers)
+		goto err_no_buf;
+	for (i = 0; i < b3dfg_nbuf; i++) {
+		struct b3dfg_buffer *buf = &fgdev->buffers[i];
+		for (j = 0; j < B3DFG_FRAMES_PER_BUFFER; j++) {
+			buf->frame[j] = kmalloc(fgdev->frame_size, GFP_KERNEL);
+			if (!buf->frame[j])
+				goto err_no_mem;
+		}
+		INIT_LIST_HEAD(&buf->list);
 	}
 
 	INIT_LIST_HEAD(&fgdev->buffer_queue);
 	init_waitqueue_head(&fgdev->buffer_waitqueue);
 	spin_lock_init(&fgdev->buffer_lock);
+	spin_lock_init(&fgdev->cstate_lock);
 	spin_lock_init(&fgdev->triplets_dropped_lock);
-	atomic_set(&fgdev->mapping_count, 0);
-	mutex_init(&fgdev->ioctl_mutex);
 	return 0;
 
 err_no_mem:
 	free_all_frame_buffers(fgdev);
+err_no_buf:
 	return -ENOMEM;
 }
 
@@ -900,84 +946,112 @@ static int __devinit b3dfg_probe(struct pci_dev *pdev,
 	int r = 0;
 	int minor = get_free_minor();
 	dev_t devno = MKDEV(MAJOR(b3dfg_devt), minor);
+	unsigned long res_len;
+	resource_size_t res_base;
 
 	if (fgdev == NULL)
 		return -ENOMEM;
 
 	if (minor < 0) {
-		printk(KERN_ERR PFX "too many devices found!\n");
-		return -EIO;
+		dev_err(&pdev->dev, "too many devices found!\n");
+		r = -EIO;
+		goto err_free;
 	}
 
 	b3dfg_devices[minor] = 1;
-	printk(KERN_INFO PFX "probe device at %s with IRQ %d\n",
-		pci_name(pdev), pdev->irq);
+	dev_info(&pdev->dev, "probe device with IRQ %d\n", pdev->irq);
 
 	cdev_init(&fgdev->chardev, &b3dfg_fops);
 	fgdev->chardev.owner = THIS_MODULE;
 
 	r = cdev_add(&fgdev->chardev, devno, 1);
-	if (r)
-		goto err1;
+	if (r) {
+		dev_err(&pdev->dev, "cannot add char device\n");
+		goto err_release_minor;
+	}
 
-	fgdev->classdev = class_device_create(b3dfg_class, NULL, devno, &pdev->dev,
-		DRIVER_NAME "%d", minor);
+	fgdev->classdev = class_device_create(b3dfg_class, NULL, devno,
+					      &pdev->dev, DRIVER_NAME "%d",
+					      minor);
 	if (IS_ERR(fgdev->classdev)) {
+		dev_err(&pdev->dev, "cannot create class device\n");
 		r = PTR_ERR(fgdev->classdev);
-		goto err2;
+		goto err_del_cdev;
 	}
 
 	r = pci_enable_device(pdev);
-	if (r)
-		goto err3;
+	if (r) {
+		dev_err(&pdev->dev, "cannot enable PCI device\n");
+		goto err_dev_unreg;
+	}
 
-	if (pci_resource_len(pdev, B3DFG_BAR_REGS) != B3DFG_REGS_LENGTH) {
-		printk(KERN_ERR PFX "invalid register resource size\n");
-		goto err4;
+	res_len = pci_resource_len(pdev, B3DFG_BAR_REGS);
+	if (res_len != B3DFG_REGS_LENGTH) {
+		dev_err(&pdev->dev, "invalid register resource size\n");
+		r = -EIO;
+		goto err_disable;
 	}
 
 	if (pci_resource_flags(pdev, B3DFG_BAR_REGS) != IORESOURCE_MEM) {
-		printk(KERN_ERR PFX "invalid resource flags");
-		goto err4;
+		dev_err(&pdev->dev, "invalid resource flags\n");
+		r = -EIO;
+		goto err_disable;
 	}
 
-	fgdev->regs = ioremap_nocache(pci_resource_start(pdev, B3DFG_BAR_REGS),
-		B3DFG_REGS_LENGTH);
+	r = pci_request_regions(pdev, DRIVER_NAME);
+	if (r) {
+		dev_err(&pdev->dev, "cannot obtain PCI resources\n");
+		goto err_disable;
+	}
+
+	pci_set_master(pdev);
+
+	r = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
+	if (r) {
+		dev_err(&pdev->dev, "no usable DMA configuration\n");
+		goto err_free_res;
+	}
+
+	res_base = pci_resource_start(pdev, B3DFG_BAR_REGS);
+	fgdev->regs = ioremap_nocache(res_base, res_len);
 	if (!fgdev->regs) {
-		printk(KERN_ERR PFX "regs ioremap failed\n");
-		goto err4;
+		dev_err(&pdev->dev, "regs ioremap failed\n");
+		r = -EIO;
+		goto err_free_res;
 	}
 
 	fgdev->pdev = pdev;
 	pci_set_drvdata(pdev, fgdev);
 	r = b3dfg_init_dev(fgdev);
 	if (r < 0) {
-		printk(KERN_ERR PFX "failed to initalize device\n");
-		goto err5;
+		dev_err(&pdev->dev, "failed to initalize device\n");
+		goto err_unmap;
 	}
 
 	r = request_irq(pdev->irq, b3dfg_intr, IRQF_SHARED, DRIVER_NAME, fgdev);
 	if (r) {
-		printk(KERN_ERR PFX "couldn't request irq %d\n", pdev->irq);
-		goto err6;
+		dev_err(&pdev->dev, "couldn't request irq %d\n", pdev->irq);
+		goto err_free_bufs;
 	}
 
 	return 0;
 
-err6:
+err_free_bufs:
 	free_all_frame_buffers(fgdev);
-err5:
+err_unmap:
 	iounmap(fgdev->regs);
-err4:
+err_free_res:
+	pci_release_regions(pdev);
+err_disable:
 	pci_disable_device(pdev);
-err3:
+err_dev_unreg:
 	class_device_unregister(fgdev->classdev);
-err2:
+err_del_cdev:
 	cdev_del(&fgdev->chardev);
-err1:
+err_release_minor:
+	b3dfg_devices[minor] = 0;
+err_free:
 	kfree(fgdev);
-	if (minor >= 0)
-		b3dfg_devices[minor] = 0;
 	return r;
 }
 
@@ -986,10 +1060,11 @@ static void __devexit b3dfg_remove(struct pci_dev *pdev)
 	struct b3dfg_dev *fgdev = pci_get_drvdata(pdev);
 	unsigned int minor = MINOR(fgdev->chardev.dev);
 
-	printk(KERN_INFO PFX "remove\n");
+	dev_dbg(&pdev->dev, "remove\n");
 
 	free_irq(pdev->irq, fgdev);
 	iounmap(fgdev->regs);
+	pci_release_regions(pdev);
 	pci_disable_device(pdev);
 	class_device_unregister(fgdev->classdev);
 	cdev_del(&fgdev->chardev);
@@ -1002,14 +1077,20 @@ static struct pci_driver b3dfg_driver = {
 	.name = DRIVER_NAME,
 	.id_table = b3dfg_ids,
 	.probe = b3dfg_probe,
-	.remove = b3dfg_remove,
+	.remove = __devexit_p(b3dfg_remove),
 };
 
 static int __init b3dfg_module_init(void)
 {
 	int r;
 
-	printk(KERN_INFO PFX "loaded\n");
+	if (b3dfg_nbuf < 2) {
+		printk(KERN_ERR DRIVER_NAME
+		       ": buffer_count is out of range (must be >= 2)");
+		return -EINVAL;
+	}
+
+	printk(KERN_INFO DRIVER_NAME ": loaded\n");
 
 	b3dfg_class = class_create(THIS_MODULE, DRIVER_NAME);
 	if (IS_ERR(b3dfg_class))
@@ -1034,7 +1115,7 @@ static int __init b3dfg_module_init(void)
 
 static void __exit b3dfg_module_exit(void)
 {
-	printk(KERN_INFO PFX "unloaded\n");
+	printk(KERN_INFO DRIVER_NAME ": unloaded\n");
 	pci_unregister_driver(&b3dfg_driver);
 	unregister_chrdev_region(b3dfg_devt, B3DFG_MAX_DEVS);
 	class_destroy(b3dfg_class);
@@ -1042,8 +1123,3 @@ static void __exit b3dfg_module_exit(void)
 
 module_init(b3dfg_module_init);
 module_exit(b3dfg_module_exit);
-MODULE_AUTHOR("Daniel Drake <ddrake@brontes3d.com>");
-MODULE_DESCRIPTION("Brontes frame grabber driver");
-MODULE_LICENSE("GPL");
-MODULE_DEVICE_TABLE(pci, b3dfg_ids);
-