V4L/DVB (13429): cx18: Add Memory Descriptor List (MDL) layer to buffer handling

Add a Memory Descriptor List (MDL) layer to buffer handling to implement
scatter-gather I/O.  Currently there is still only 1 buffer per MDL.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-driver.c

@@ -669,6 +669,12 @@ static int __devinit cx18_init_struct1(struct cx18 *cx)
 	cx->vbi.in.type = V4L2_BUF_TYPE_VBI_CAPTURE;
 	cx->vbi.sliced_in = &cx->vbi.in.fmt.sliced;
 
+	/* IVTV style VBI insertion into MPEG streams */
+	INIT_LIST_HEAD(&cx->vbi.sliced_mpeg_buf.list);
+	INIT_LIST_HEAD(&cx->vbi.sliced_mpeg_mdl.list);
+	INIT_LIST_HEAD(&cx->vbi.sliced_mpeg_mdl.buf_list);
+	list_add(&cx->vbi.sliced_mpeg_buf.list,
+		 &cx->vbi.sliced_mpeg_mdl.buf_list);
 	return 0;
 }
 

drivers/media/video/cx18/cx18-driver.h

@@ -246,8 +246,8 @@ struct cx18_options {
 	int radio;		/* enable/disable radio */
 };
 
-/* per-buffer bit flags */
-#define CX18_F_B_NEED_BUF_SWAP  0	/* this buffer should be byte swapped */
+/* per-mdl bit flags */
+#define CX18_F_M_NEED_SWAP  0	/* mdl buffer data must be endianess swapped */
 
 /* per-stream, s_flags */
 #define CX18_F_S_CLAIMED 	3	/* this stream is claimed */
@@ -274,15 +274,26 @@ struct cx18_options {
 struct cx18_buffer {
 	struct list_head list;
 	dma_addr_t dma_handle;
-	u32 id;
-	unsigned long b_flags;
-	unsigned skipped;
 	char *buf;
 
 	u32 bytesused;
 	u32 readpos;
 };
 
+struct cx18_mdl {
+	struct list_head list;
+	u32 id;		/* index into cx->scb->cpu_mdl[] of 1st cx18_mdl_ent */
+
+	unsigned int skipped;
+	unsigned long m_flags;
+
+	struct list_head buf_list;
+	struct cx18_buffer *curr_buf; /* current buffer in list for reading */
+
+	u32 bytesused;
+	u32 readpos;
+};
+
 struct cx18_queue {
 	struct list_head list;
 	atomic_t depth;
@@ -346,14 +357,20 @@ struct cx18_stream {
 				   PCI_DMA_NONE */
 	wait_queue_head_t waitq;
 
-	/* Buffer Stats */
-	u32 buffers;
-	u32 buf_size;
+	/* Buffers */
+	struct list_head buf_pool;	/* buffers not attached to an MDL */
+	u32 buffers;			/* total buffers owned by this stream */
+	u32 buf_size;			/* size in bytes of a single buffer */
+
+	/* MDL sizes - all stream MDLs are the same size */
+	u32 bufs_per_mdl;
+	u32 mdl_size;		/* total bytes in all buffers in a mdl */
 
-	/* Buffer Queues */
-	struct cx18_queue q_free;	/* free buffers */
-	struct cx18_queue q_busy;	/* busy buffers - in use by firmware */
-	struct cx18_queue q_full;	/* full buffers - data for user apps */
+	/* MDL Queues */
+	struct cx18_queue q_free;	/* free - in rotation, not committed */
+	struct cx18_queue q_busy;	/* busy - in use by firmware */
+	struct cx18_queue q_full;	/* full - data for user apps */
+	struct cx18_queue q_idle;	/* idle - not in rotation */
 
 	struct work_struct out_work_order;
 
@@ -481,10 +498,11 @@ struct vbi_info {
 	u32 inserted_frame;
 
 	/*
-	 * A dummy driver stream transfer buffer with a copy of the next
+	 * A dummy driver stream transfer mdl & buffer with a copy of the next
 	 * sliced_mpeg_data[] buffer for output to userland apps.
 	 * Only used in cx18-fileops.c, but its state needs to persist at times.
 	 */
+	struct cx18_mdl sliced_mpeg_mdl;
 	struct cx18_buffer sliced_mpeg_buf;
 };
 
@@ -511,7 +529,6 @@ struct cx18 {
 	u8 is_60hz;
 	u8 nof_inputs;		/* number of video inputs */
 	u8 nof_audio_inputs;	/* number of audio inputs */
-	u16 buffer_id;		/* buffer ID counter */
 	u32 v4l2_cap;		/* V4L2 capabilities of card */
 	u32 hw_flags; 		/* Hardware description of the board */
 	unsigned int free_mdl_idx;

drivers/media/video/cx18/cx18-fileops.c

@@ -166,11 +166,12 @@ static void cx18_dualwatch(struct cx18 *cx)
 }
 
 
-static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block, int *err)
+static struct cx18_mdl *cx18_get_mdl(struct cx18_stream *s, int non_block,
+				     int *err)
 {
 	struct cx18 *cx = s->cx;
 	struct cx18_stream *s_vbi = &cx->streams[CX18_ENC_STREAM_TYPE_VBI];
-	struct cx18_buffer *buf;
+	struct cx18_mdl *mdl;
 	DEFINE_WAIT(wait);
 
 	*err = 0;
@@ -185,32 +186,33 @@ static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block,
 			}
 			if (test_bit(CX18_F_S_INTERNAL_USE, &s_vbi->s_flags) &&
 			    !test_bit(CX18_F_S_APPL_IO, &s_vbi->s_flags)) {
-				while ((buf = cx18_dequeue(s_vbi, &s_vbi->q_full))) {
+				while ((mdl = cx18_dequeue(s_vbi,
+							   &s_vbi->q_full))) {
 					/* byteswap and process VBI data */
-					cx18_process_vbi_data(cx, buf,
+					cx18_process_vbi_data(cx, mdl,
 							      s_vbi->type);
-					cx18_stream_put_buf_fw(s_vbi, buf);
+					cx18_stream_put_mdl_fw(s_vbi, mdl);
 				}
 			}
-			buf = &cx->vbi.sliced_mpeg_buf;
-			if (buf->readpos != buf->bytesused)
-				return buf;
+			mdl = &cx->vbi.sliced_mpeg_mdl;
+			if (mdl->readpos != mdl->bytesused)
+				return mdl;
 		}
 
 		/* do we have new data? */
-		buf = cx18_dequeue(s, &s->q_full);
-		if (buf) {
-			if (!test_and_clear_bit(CX18_F_B_NEED_BUF_SWAP,
-						&buf->b_flags))
-				return buf;
+		mdl = cx18_dequeue(s, &s->q_full);
+		if (mdl) {
+			if (!test_and_clear_bit(CX18_F_M_NEED_SWAP,
+						&mdl->m_flags))
+				return mdl;
 			if (s->type == CX18_ENC_STREAM_TYPE_MPG)
 				/* byteswap MPG data */
-				cx18_buf_swap(buf);
+				cx18_mdl_swap(mdl);
 			else {
 				/* byteswap and process VBI data */
-				cx18_process_vbi_data(cx, buf, s->type);
+				cx18_process_vbi_data(cx, mdl, s->type);
 			}
-			return buf;
+			return mdl;
 		}
 
 		/* return if end of stream */
@@ -241,21 +243,28 @@ static struct cx18_buffer *cx18_get_buffer(struct cx18_stream *s, int non_block,
 	}
 }
 
-static void cx18_setup_sliced_vbi_buf(struct cx18 *cx)
+static void cx18_setup_sliced_vbi_mdl(struct cx18 *cx)
 {
+	struct cx18_mdl *mdl = &cx->vbi.sliced_mpeg_mdl;
+	struct cx18_buffer *buf = &cx->vbi.sliced_mpeg_buf;
 	int idx = cx->vbi.inserted_frame % CX18_VBI_FRAMES;
 
-	cx->vbi.sliced_mpeg_buf.buf = cx->vbi.sliced_mpeg_data[idx];
-	cx->vbi.sliced_mpeg_buf.bytesused = cx->vbi.sliced_mpeg_size[idx];
-	cx->vbi.sliced_mpeg_buf.readpos = 0;
+	buf->buf = cx->vbi.sliced_mpeg_data[idx];
+	buf->bytesused = cx->vbi.sliced_mpeg_size[idx];
+	buf->readpos = 0;
+
+	mdl->curr_buf = NULL;
+	mdl->bytesused = cx->vbi.sliced_mpeg_size[idx];
+	mdl->readpos = 0;
 }
 
 static size_t cx18_copy_buf_to_user(struct cx18_stream *s,
-		struct cx18_buffer *buf, char __user *ubuf, size_t ucount)
+	struct cx18_buffer *buf, char __user *ubuf, size_t ucount, bool *stop)
 {
 	struct cx18 *cx = s->cx;
 	size_t len = buf->bytesused - buf->readpos;
 
+	*stop = false;
 	if (len > ucount)
 		len = ucount;
 	if (cx->vbi.insert_mpeg && s->type == CX18_ENC_STREAM_TYPE_MPG &&
@@ -335,7 +344,8 @@ static size_t cx18_copy_buf_to_user(struct cx18_stream *s,
 				/* We declare we actually found a Program Pack*/
 				cx->search_pack_header = 0; /* expect vid PES */
 				len = (char *)q - start;
-				cx18_setup_sliced_vbi_buf(cx);
+				cx18_setup_sliced_vbi_mdl(cx);
+				*stop = true;
 				break;
 			}
 		}
@@ -352,6 +362,60 @@ static size_t cx18_copy_buf_to_user(struct cx18_stream *s,
 	return len;
 }
 
+/**
+ * list_entry_is_past_end - check if a previous loop cursor is off list end
+ * @pos:	the type * previously used as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Check if the entry's list_head is the head of the list, thus it's not a
+ * real entry but was the loop cursor that walked past the end
+ */
+#define list_entry_is_past_end(pos, head, member) \
+	(&pos->member == (head))
+
+static size_t cx18_copy_mdl_to_user(struct cx18_stream *s,
+		struct cx18_mdl *mdl, char __user *ubuf, size_t ucount)
+{
+	size_t tot_written = 0;
+	int rc;
+	bool stop = false;
+
+	if (mdl->curr_buf == NULL)
+		mdl->curr_buf = list_first_entry(&mdl->buf_list,
+						 struct cx18_buffer, list);
+
+	if (list_entry_is_past_end(mdl->curr_buf, &mdl->buf_list, list)) {
+		/*
+		 * For some reason we've exhausted the buffers, but the MDL
+		 * object still said some data was unread.
+		 * Fix that and bail out.
+		 */
+		mdl->readpos = mdl->bytesused;
+		return 0;
+	}
+
+	list_for_each_entry_from(mdl->curr_buf, &mdl->buf_list, list) {
+
+		if (mdl->curr_buf->readpos >= mdl->curr_buf->bytesused)
+			continue;
+
+		rc = cx18_copy_buf_to_user(s, mdl->curr_buf, ubuf + tot_written,
+					   ucount - tot_written, &stop);
+		if (rc < 0)
+			return rc;
+		mdl->readpos += rc;
+		tot_written += rc;
+
+		if (stop ||	/* Forced stopping point for VBI insertion */
+		    tot_written >= ucount ||	/* Reader request statisfied */
+		    mdl->curr_buf->readpos < mdl->curr_buf->bytesused ||
+		    mdl->readpos >= mdl->bytesused) /* MDL buffers drained */
+			break;
+	}
+	return tot_written;
+}
+
 static ssize_t cx18_read(struct cx18_stream *s, char __user *ubuf,
 		size_t tot_count, int non_block)
 {
@@ -373,12 +437,12 @@ static ssize_t cx18_read(struct cx18_stream *s, char __user *ubuf,
 		single_frame = 1;
 
 	for (;;) {
-		struct cx18_buffer *buf;
+		struct cx18_mdl *mdl;
 		int rc;
 
-		buf = cx18_get_buffer(s, non_block, &rc);
+		mdl = cx18_get_mdl(s, non_block, &rc);
 		/* if there is no data available... */
-		if (buf == NULL) {
+		if (mdl == NULL) {
 			/* if we got data, then return that regardless */
 			if (tot_written)
 				break;
@@ -392,20 +456,20 @@ static ssize_t cx18_read(struct cx18_stream *s, char __user *ubuf,
 			return rc;
 		}
 
-		rc = cx18_copy_buf_to_user(s, buf, ubuf + tot_written,
+		rc = cx18_copy_mdl_to_user(s, mdl, ubuf + tot_written,
 				tot_count - tot_written);
 
-		if (buf != &cx->vbi.sliced_mpeg_buf) {
-			if (buf->readpos == buf->bytesused)
-				cx18_stream_put_buf_fw(s, buf);
+		if (mdl != &cx->vbi.sliced_mpeg_mdl) {
+			if (mdl->readpos == mdl->bytesused)
+				cx18_stream_put_mdl_fw(s, mdl);
 			else
-				cx18_push(s, buf, &s->q_full);
-		} else if (buf->readpos == buf->bytesused) {
+				cx18_push(s, mdl, &s->q_full);
+		} else if (mdl->readpos == mdl->bytesused) {
 			int idx = cx->vbi.inserted_frame % CX18_VBI_FRAMES;
 
 			cx->vbi.sliced_mpeg_size[idx] = 0;
 			cx->vbi.inserted_frame++;
-			cx->vbi_data_inserted += buf->bytesused;
+			cx->vbi_data_inserted += mdl->bytesused;
 		}
 		if (rc < 0)
 			return rc;

drivers/media/video/cx18/cx18-ioctl.c

@@ -910,7 +910,8 @@ static int cx18_log_status(struct file *file, void *fh)
 			continue;
 		CX18_INFO("Stream %s: status 0x%04lx, %d%% of %d KiB (%d buffers) in use\n",
 			  s->name, s->s_flags,
-			  atomic_read(&s->q_full.depth) * 100 / s->buffers,
+			  atomic_read(&s->q_full.depth) * s->bufs_per_mdl * 100
+			   / s->buffers,
 			  (s->buffers * s->buf_size) / 1024, s->buffers);
 	}
 	CX18_INFO("Read MPEG/VBI: %lld/%lld bytes\n",

drivers/media/video/cx18/cx18-mailbox.c

@@ -131,13 +131,39 @@ static void dump_mb(struct cx18 *cx, struct cx18_mailbox *mb, char *name)
  * Functions that run in a work_queue work handling context
  */
 
+static void cx18_mdl_send_to_dvb(struct cx18_stream *s, struct cx18_mdl *mdl)
+{
+	struct cx18_buffer *buf;
+
+	if (!s->dvb.enabled || mdl->bytesused == 0)
+		return;
+
+	/* We ignore mdl and buf readpos accounting here - it doesn't matter */
+
+	/* The likely case */
+	if (list_is_singular(&mdl->buf_list)) {
+		buf = list_first_entry(&mdl->buf_list, struct cx18_buffer,
+				       list);
+		if (buf->bytesused)
+			dvb_dmx_swfilter(&s->dvb.demux,
+					 buf->buf, buf->bytesused);
+		return;
+	}
+
+	list_for_each_entry(buf, &mdl->buf_list, list) {
+		if (buf->bytesused == 0)
+			break;
+		dvb_dmx_swfilter(&s->dvb.demux, buf->buf, buf->bytesused);
+	}
+}
+
 static void epu_dma_done(struct cx18 *cx, struct cx18_in_work_order *order)
 {
 	u32 handle, mdl_ack_count, id;
 	struct cx18_mailbox *mb;
 	struct cx18_mdl_ack *mdl_ack;
 	struct cx18_stream *s;
-	struct cx18_buffer *buf;
+	struct cx18_mdl *mdl;
 	int i;
 
 	mb = &order->mb;
@@ -158,7 +184,7 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_in_work_order *order)
 		id = mdl_ack->id;
 		/*
 		 * Simple integrity check for processing a stale (and possibly
-		 * inconsistent mailbox): make sure the buffer id is in the
+		 * inconsistent mailbox): make sure the MDL id is in the
 		 * valid range for the stream.
 		 *
 		 * We go through the trouble of dealing with stale mailboxes
@@ -169,44 +195,42 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_in_work_order *order)
 		 * There are occasions when we get a half changed mailbox,
 		 * which this check catches for a handle & id mismatch.  If the
 		 * handle and id do correspond, the worst case is that we
-		 * completely lost the old buffer, but pick up the new buffer
+		 * completely lost the old MDL, but pick up the new MDL
 		 * early (but the new mdl_ack is guaranteed to be good in this
 		 * case as the firmware wouldn't point us to a new mdl_ack until
 		 * it's filled in).
 		 *
-		 * cx18_queue_get buf() will detect the lost buffers
+		 * cx18_queue_get_mdl() will detect the lost MDLs
 		 * and send them back to q_free for fw rotation eventually.
 		 */
 		if ((order->flags & CX18_F_EWO_MB_STALE_UPON_RECEIPT) &&
 		    !(id >= s->mdl_base_idx &&
 		      id < (s->mdl_base_idx + s->buffers))) {
 			CX18_WARN("Fell behind! Ignoring stale mailbox with "
-				  " inconsistent data. Lost buffer for mailbox "
+				  " inconsistent data. Lost MDL for mailbox "
 				  "seq no %d\n", mb->request);
 			break;
 		}
-		buf = cx18_queue_get_buf(s, id, mdl_ack->data_used);
+		mdl = cx18_queue_get_mdl(s, id, mdl_ack->data_used);
 
-		CX18_DEBUG_HI_DMA("DMA DONE for %s (buffer %d)\n", s->name, id);
-		if (buf == NULL) {
-			CX18_WARN("Could not find buf %d for stream %s\n",
+		CX18_DEBUG_HI_DMA("DMA DONE for %s (MDL %d)\n", s->name, id);
+		if (mdl == NULL) {
+			CX18_WARN("Could not find MDL %d for stream %s\n",
 				  id, s->name);
 			continue;
 		}
 
 		CX18_DEBUG_HI_DMA("%s recv bytesused = %d\n",
-				  s->name, buf->bytesused);
+				  s->name, mdl->bytesused);
 
 		if (s->type != CX18_ENC_STREAM_TYPE_TS)
-			cx18_enqueue(s, buf, &s->q_full);
+			cx18_enqueue(s, mdl, &s->q_full);
 		else {
-			if (s->dvb.enabled)
-				dvb_dmx_swfilter(&s->dvb.demux, buf->buf,
-						 buf->bytesused);
-			cx18_enqueue(s, buf, &s->q_free);
+			cx18_mdl_send_to_dvb(s, mdl);
+			cx18_enqueue(s, mdl, &s->q_free);
 		}
 	}
-	/* Put as many buffers as possible back into fw use */
+	/* Put as many MDLs as possible back into fw use */
 	cx18_stream_load_fw_queue(s);
 
 	wake_up(&cx->dma_waitq);
@@ -616,7 +640,7 @@ static int cx18_api_call(struct cx18 *cx, u32 cmd, int args, u32 data[])
 
 	/*
 	 * Wait for XPU to perform extra actions for the caller in some cases.
-	 * e.g. CX18_CPU_DE_RELEASE_MDL will cause the CPU to send all buffers
+	 * e.g. CX18_CPU_DE_RELEASE_MDL will cause the CPU to send all MDLs
 	 * back in a burst shortly thereafter
 	 */
 	if (info->flags & API_SLOW)

drivers/media/video/cx18/cx18-mailbox.h

@@ -39,14 +39,14 @@
 struct cx18;
 
 /*
- * This structure is used by CPU to provide completed buffers information
- * Its structure is dictrated by the layout of the SCB, required by the
+ * This structure is used by CPU to provide completed MDL & buffers information.
+ * Its structure is dictated by the layout of the SCB, required by the
  * firmware, but its defintion needs to be here, instead of in cx18-scb.h,
  * for mailbox work order scheduling
  */
 struct cx18_mdl_ack {
     u32 id;        /* ID of a completed MDL */
-    u32 data_used; /* Total data filled in the MDL for buffer 'id' */
+    u32 data_used; /* Total data filled in the MDL with 'id' */
 };
 
 /* The cx18_mailbox struct is the mailbox structure which is used for passing

drivers/media/video/cx18/cx18-queue.c

@@ -26,6 +26,7 @@
 #include "cx18-queue.h"
 #include "cx18-streams.h"
 #include "cx18-scb.h"
+#include "cx18-io.h"
 
 void cx18_buf_swap(struct cx18_buffer *buf)
 {
@@ -35,6 +36,17 @@ void cx18_buf_swap(struct cx18_buffer *buf)
 		swab32s((u32 *)(buf->buf + i));
 }
 
+void _cx18_mdl_swap(struct cx18_mdl *mdl)
+{
+	struct cx18_buffer *buf;
+
+	list_for_each_entry(buf, &mdl->buf_list, list) {
+		if (buf->bytesused == 0)
+			break;
+		cx18_buf_swap(buf);
+	}
+}
+
 void cx18_queue_init(struct cx18_queue *q)
 {
 	INIT_LIST_HEAD(&q->list);
@@ -42,15 +54,16 @@ void cx18_queue_init(struct cx18_queue *q)
 	q->bytesused = 0;
 }
 
-struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
+struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_mdl *mdl,
 				 struct cx18_queue *q, int to_front)
 {
-	/* clear the buffer if it is not to be enqueued to the full queue */
+	/* clear the mdl if it is not to be enqueued to the full queue */
 	if (q != &s->q_full) {
-		buf->bytesused = 0;
-		buf->readpos = 0;
-		buf->b_flags = 0;
-		buf->skipped = 0;
+		mdl->bytesused = 0;
+		mdl->readpos = 0;
+		mdl->m_flags = 0;
+		mdl->skipped = 0;
+		mdl->curr_buf = NULL;
 	}
 
 	/* q_busy is restricted to a max buffer count imposed by firmware */
@@ -61,125 +74,270 @@ struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
 	spin_lock(&q->lock);
 
 	if (to_front)
-		list_add(&buf->list, &q->list); /* LIFO */
+		list_add(&mdl->list, &q->list); /* LIFO */
 	else
-		list_add_tail(&buf->list, &q->list); /* FIFO */
-	q->bytesused += buf->bytesused - buf->readpos;
+		list_add_tail(&mdl->list, &q->list); /* FIFO */
+	q->bytesused += mdl->bytesused - mdl->readpos;
 	atomic_inc(&q->depth);
 
 	spin_unlock(&q->lock);
 	return q;
 }
 
-struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
+struct cx18_mdl *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
 {
-	struct cx18_buffer *buf = NULL;
+	struct cx18_mdl *mdl = NULL;
 
 	spin_lock(&q->lock);
 	if (!list_empty(&q->list)) {
-		buf = list_first_entry(&q->list, struct cx18_buffer, list);
-		list_del_init(&buf->list);
-		q->bytesused -= buf->bytesused - buf->readpos;
-		buf->skipped = 0;
+		mdl = list_first_entry(&q->list, struct cx18_mdl, list);
+		list_del_init(&mdl->list);
+		q->bytesused -= mdl->bytesused - mdl->readpos;
+		mdl->skipped = 0;
 		atomic_dec(&q->depth);
 	}
 	spin_unlock(&q->lock);
-	return buf;
+	return mdl;
+}
+
+static void _cx18_mdl_set_buf_bytesused(struct cx18_stream *s,
+					struct cx18_mdl *mdl)
+{
+	struct cx18_buffer *buf;
+	u32 buf_size = s->buf_size;
+	u32 bytesused = mdl->bytesused;
+
+	list_for_each_entry(buf, &mdl->buf_list, list) {
+		buf->readpos = 0;
+		if (bytesused >= buf_size) {
+			buf->bytesused = buf_size;
+			bytesused -= buf_size;
+		} else {
+			buf->bytesused = bytesused;
+			bytesused = 0;
+		}
+	}
 }
 
-struct cx18_buffer *cx18_queue_get_buf(struct cx18_stream *s, u32 id,
+static inline void cx18_mdl_set_buf_bytesused(struct cx18_stream *s,
+					      struct cx18_mdl *mdl)
+{
+	struct cx18_buffer *buf;
+
+	if (list_is_singular(&mdl->buf_list)) {
+		buf = list_first_entry(&mdl->buf_list, struct cx18_buffer,
+				       list);
+		buf->bytesused = mdl->bytesused;
+		buf->readpos = 0;
+	} else {
+		_cx18_mdl_set_buf_bytesused(s, mdl);
+	}
+}
+
+struct cx18_mdl *cx18_queue_get_mdl(struct cx18_stream *s, u32 id,
 	u32 bytesused)
 {
 	struct cx18 *cx = s->cx;
-	struct cx18_buffer *buf;
-	struct cx18_buffer *tmp;
-	struct cx18_buffer *ret = NULL;
+	struct cx18_mdl *mdl;
+	struct cx18_mdl *tmp;
+	struct cx18_mdl *ret = NULL;
 	LIST_HEAD(sweep_up);
 
 	/*
 	 * We don't have to acquire multiple q locks here, because we are
 	 * serialized by the single threaded work handler.
-	 * Buffers from the firmware will thus remain in order as
+	 * MDLs from the firmware will thus remain in order as
 	 * they are moved from q_busy to q_full or to the dvb ring buffer.
 	 */
 	spin_lock(&s->q_busy.lock);
-	list_for_each_entry_safe(buf, tmp, &s->q_busy.list, list) {
+	list_for_each_entry_safe(mdl, tmp, &s->q_busy.list, list) {
 		/*
 		 * We should find what the firmware told us is done,
 		 * right at the front of the queue.  If we don't, we likely have
-		 * missed a buffer done message from the firmware.
-		 * Once we skip a buffer repeatedly, relative to the size of
+		 * missed an mdl done message from the firmware.
+		 * Once we skip an mdl repeatedly, relative to the size of
 		 * q_busy, we have high confidence we've missed it.
 		 */
-		if (buf->id != id) {
-			buf->skipped++;
-			if (buf->skipped >= atomic_read(&s->q_busy.depth)-1) {
-				/* buffer must have fallen out of rotation */
-				CX18_WARN("Skipped %s, buffer %d, %d "
+		if (mdl->id != id) {
+			mdl->skipped++;
+			if (mdl->skipped >= atomic_read(&s->q_busy.depth)-1) {
+				/* mdl must have fallen out of rotation */
+				CX18_WARN("Skipped %s, MDL %d, %d "
 					  "times - it must have dropped out of "
-					  "rotation\n", s->name, buf->id,
-					  buf->skipped);
+					  "rotation\n", s->name, mdl->id,
+					  mdl->skipped);
 				/* Sweep it up to put it back into rotation */
-				list_move_tail(&buf->list, &sweep_up);
+				list_move_tail(&mdl->list, &sweep_up);
 				atomic_dec(&s->q_busy.depth);
 			}
 			continue;
 		}
 		/*
-		 * We pull the desired buffer off of the queue here.  Something
+		 * We pull the desired mdl off of the queue here.  Something
 		 * will have to put it back on a queue later.
 		 */
-		list_del_init(&buf->list);
+		list_del_init(&mdl->list);
 		atomic_dec(&s->q_busy.depth);
-		ret = buf;
+		ret = mdl;
 		break;
 	}
 	spin_unlock(&s->q_busy.lock);
 
 	/*
-	 * We found the buffer for which we were looking.  Get it ready for
+	 * We found the mdl for which we were looking.  Get it ready for
 	 * the caller to put on q_full or in the dvb ring buffer.
 	 */
 	if (ret != NULL) {
 		ret->bytesused = bytesused;
 		ret->skipped = 0;
-		/* readpos and b_flags were 0'ed when the buf went on q_busy */
-		cx18_buf_sync_for_cpu(s, ret);
+		/* 0'ed readpos, m_flags & curr_buf when mdl went on q_busy */
+		cx18_mdl_set_buf_bytesused(s, ret);
+		cx18_mdl_sync_for_cpu(s, ret);
 		if (s->type != CX18_ENC_STREAM_TYPE_TS)
-			set_bit(CX18_F_B_NEED_BUF_SWAP, &ret->b_flags);
+			set_bit(CX18_F_M_NEED_SWAP, &ret->m_flags);
 	}
 
-	/* Put any buffers the firmware is ignoring back into normal rotation */
-	list_for_each_entry_safe(buf, tmp, &sweep_up, list) {
-		list_del_init(&buf->list);
-		cx18_enqueue(s, buf, &s->q_free);
+	/* Put any mdls the firmware is ignoring back into normal rotation */
+	list_for_each_entry_safe(mdl, tmp, &sweep_up, list) {
+		list_del_init(&mdl->list);
+		cx18_enqueue(s, mdl, &s->q_free);
 	}
 	return ret;
 }
 
-/* Move all buffers of a queue to q_free, while flushing the buffers */
-static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q)
+/* Move all mdls of a queue, while flushing the mdl */
+static void cx18_queue_flush(struct cx18_stream *s,
+			     struct cx18_queue *q_src, struct cx18_queue *q_dst)
 {
-	struct cx18_buffer *buf;
+	struct cx18_mdl *mdl;
 
-	if (q == &s->q_free)
+	/* It only makes sense to flush to q_free or q_idle */
+	if (q_src == q_dst || q_dst == &s->q_full || q_dst == &s->q_busy)
 		return;
 
-	spin_lock(&q->lock);
-	while (!list_empty(&q->list)) {
-		buf = list_first_entry(&q->list, struct cx18_buffer, list);
-		list_move_tail(&buf->list, &s->q_free.list);
-		buf->bytesused = buf->readpos = buf->b_flags = buf->skipped = 0;
-		atomic_inc(&s->q_free.depth);
+	spin_lock(&q_src->lock);
+	spin_lock(&q_dst->lock);
+	while (!list_empty(&q_src->list)) {
+		mdl = list_first_entry(&q_src->list, struct cx18_mdl, list);
+		list_move_tail(&mdl->list, &q_dst->list);
+		mdl->bytesused = 0;
+		mdl->readpos = 0;
+		mdl->m_flags = 0;
+		mdl->skipped = 0;
+		mdl->curr_buf = NULL;
+		atomic_inc(&q_dst->depth);
 	}
-	cx18_queue_init(q);
-	spin_unlock(&q->lock);
+	cx18_queue_init(q_src);
+	spin_unlock(&q_src->lock);
+	spin_unlock(&q_dst->lock);
 }
 
 void cx18_flush_queues(struct cx18_stream *s)
 {
-	cx18_queue_flush(s, &s->q_busy);
-	cx18_queue_flush(s, &s->q_full);
+	cx18_queue_flush(s, &s->q_busy, &s->q_free);
+	cx18_queue_flush(s, &s->q_full, &s->q_free);
+}
+
+/*
+ * Note, s->buf_pool is not protected by a lock,
+ * the stream better not have *anything* going on when calling this
+ */
+void cx18_unload_queues(struct cx18_stream *s)
+{
+	struct cx18_queue *q_idle = &s->q_idle;
+	struct cx18_mdl *mdl;
+	struct cx18_buffer *buf;
+
+	/* Move all MDLS to q_idle */
+	cx18_queue_flush(s, &s->q_busy, q_idle);
+	cx18_queue_flush(s, &s->q_full, q_idle);
+	cx18_queue_flush(s, &s->q_free, q_idle);
+
+	/* Reset MDL id's and move all buffers back to the stream's buf_pool */
+	spin_lock(&q_idle->lock);
+	list_for_each_entry(mdl, &q_idle->list, list) {
+		while (!list_empty(&mdl->buf_list)) {
+			buf = list_first_entry(&mdl->buf_list,
+					       struct cx18_buffer, list);
+			list_move_tail(&buf->list, &s->buf_pool);
+			buf->bytesused = 0;
+			buf->readpos = 0;
+		}
+		mdl->id = s->mdl_base_idx; /* reset id to a "safe" value */
+		/* all other mdl fields were cleared by cx18_queue_flush() */
+	}
+	spin_unlock(&q_idle->lock);
+}
+
+/*
+ * Note, s->buf_pool is not protected by a lock,
+ * the stream better not have *anything* going on when calling this
+ */
+void cx18_load_queues(struct cx18_stream *s)
+{
+	struct cx18 *cx = s->cx;
+	struct cx18_mdl *mdl;
+	struct cx18_buffer *buf;
+	int mdl_id;
+	int i;
+
+	/*
+	 * Attach buffers to MDLs, give the MDLs ids, and add MDLs to q_free
+	 * Excess MDLs are left on q_idle
+	 * Excess buffers are left in buf_pool and/or on an MDL in q_idle
+	 */
+	mdl_id = s->mdl_base_idx;
+	for (mdl = cx18_dequeue(s, &s->q_idle), i = s->bufs_per_mdl;
+	     mdl != NULL && i == s->bufs_per_mdl;
+	     mdl = cx18_dequeue(s, &s->q_idle)) {
+
+		mdl->id = mdl_id;
+
+		for (i = 0; i < s->bufs_per_mdl; i++) {
+			if (list_empty(&s->buf_pool))
+				break;
+
+			buf = list_first_entry(&s->buf_pool, struct cx18_buffer,
+					       list);
+			list_move_tail(&buf->list, &mdl->buf_list);
+
+			/* update the firmware's MDL array with this buffer */
+			cx18_writel(cx, buf->dma_handle,
+				    &cx->scb->cpu_mdl[mdl_id + i].paddr);
+			cx18_writel(cx, s->buf_size,
+				    &cx->scb->cpu_mdl[mdl_id + i].length);
+		}
+
+		if (i == s->bufs_per_mdl)
+			cx18_enqueue(s, mdl, &s->q_free);
+		else
+			cx18_push(s, mdl, &s->q_idle); /* not enough buffers */
+		mdl_id += i;
+	}
+}
+
+void _cx18_mdl_sync_for_cpu(struct cx18_stream *s, struct cx18_mdl *mdl)
+{
+	int dma = s->dma;
+	u32 buf_size = s->buf_size;
+	struct pci_dev *pci_dev = s->cx->pci_dev;
+	struct cx18_buffer *buf;
+
+	list_for_each_entry(buf, &mdl->buf_list, list)
+		pci_dma_sync_single_for_cpu(pci_dev, buf->dma_handle,
+					    buf_size, dma);
+}
+
+void _cx18_mdl_sync_for_device(struct cx18_stream *s, struct cx18_mdl *mdl)
+{
+	int dma = s->dma;
+	u32 buf_size = s->buf_size;
+	struct pci_dev *pci_dev = s->cx->pci_dev;
+	struct cx18_buffer *buf;
+
+	list_for_each_entry(buf, &mdl->buf_list, list)
+		pci_dma_sync_single_for_device(pci_dev, buf->dma_handle,
+					       buf_size, dma);
 }
 
 int cx18_stream_alloc(struct cx18_stream *s)
@@ -207,24 +365,40 @@ int cx18_stream_alloc(struct cx18_stream *s)
 
 	s->mdl_base_idx = cx->free_mdl_idx;
 
-	/* allocate stream buffers. Initially all buffers are in q_free. */
+	/* allocate stream buffers and MDLs */
 	for (i = 0; i < s->buffers; i++) {
-		struct cx18_buffer *buf = kzalloc(sizeof(struct cx18_buffer),
-						GFP_KERNEL|__GFP_NOWARN);
+		struct cx18_mdl *mdl;
+		struct cx18_buffer *buf;
 
-		if (buf == NULL)
+		/* 1 MDL per buffer to handle the worst & also default case */
+		mdl = kzalloc(sizeof(struct cx18_mdl), GFP_KERNEL|__GFP_NOWARN);
+		if (mdl == NULL)
 			break;
+
+		buf = kzalloc(sizeof(struct cx18_buffer),
+				GFP_KERNEL|__GFP_NOWARN);
+		if (buf == NULL) {
+			kfree(mdl);
+			break;
+		}
+
 		buf->buf = kmalloc(s->buf_size, GFP_KERNEL|__GFP_NOWARN);
 		if (buf->buf == NULL) {
+			kfree(mdl);
 			kfree(buf);
 			break;
 		}
-		buf->id = cx->buffer_id++;
+
+		INIT_LIST_HEAD(&mdl->list);
+		INIT_LIST_HEAD(&mdl->buf_list);
+		mdl->id = s->mdl_base_idx; /* a somewhat safe value */
+		cx18_enqueue(s, mdl, &s->q_idle);
+
 		INIT_LIST_HEAD(&buf->list);
 		buf->dma_handle = pci_map_single(s->cx->pci_dev,
 				buf->buf, s->buf_size, s->dma);
 		cx18_buf_sync_for_cpu(s, buf);
-		cx18_enqueue(s, buf, &s->q_free);
+		list_add_tail(&buf->list, &s->buf_pool);
 	}
 	if (i == s->buffers) {
 		cx->free_mdl_idx += s->buffers;
@@ -237,13 +411,21 @@ int cx18_stream_alloc(struct cx18_stream *s)
 
 void cx18_stream_free(struct cx18_stream *s)
 {
+	struct cx18_mdl *mdl;
 	struct cx18_buffer *buf;
 
-	/* move all buffers to q_free */
-	cx18_flush_queues(s);
+	/* move all buffers to buf_pool and all MDLs to q_idle */
+	cx18_unload_queues(s);
+
+	/* empty q_idle */
+	while ((mdl = cx18_dequeue(s, &s->q_idle)))
+		kfree(mdl);
+
+	/* empty buf_pool */
+	while (!list_empty(&s->buf_pool)) {
+		buf = list_first_entry(&s->buf_pool, struct cx18_buffer, list);
+		list_del_init(&buf->list);
 
-	/* empty q_free */
-	while ((buf = cx18_dequeue(s, &s->q_free))) {
 		pci_unmap_single(s->cx->pci_dev, buf->dma_handle,
 				s->buf_size, s->dma);
 		kfree(buf->buf);

drivers/media/video/cx18/cx18-queue.h

@@ -33,6 +33,19 @@ static inline void cx18_buf_sync_for_cpu(struct cx18_stream *s,
 				s->buf_size, s->dma);
 }
 
+void _cx18_mdl_sync_for_cpu(struct cx18_stream *s, struct cx18_mdl *mdl);
+
+static inline void cx18_mdl_sync_for_cpu(struct cx18_stream *s,
+					 struct cx18_mdl *mdl)
+{
+	if (list_is_singular(&mdl->buf_list))
+		cx18_buf_sync_for_cpu(s, list_first_entry(&mdl->buf_list,
+							  struct cx18_buffer,
+							  list));
+	else
+		_cx18_mdl_sync_for_cpu(s, mdl);
+}
+
 static inline void cx18_buf_sync_for_device(struct cx18_stream *s,
 	struct cx18_buffer *buf)
 {
@@ -40,32 +53,59 @@ static inline void cx18_buf_sync_for_device(struct cx18_stream *s,
 				s->buf_size, s->dma);
 }
 
+void _cx18_mdl_sync_for_device(struct cx18_stream *s, struct cx18_mdl *mdl);
+
+static inline void cx18_mdl_sync_for_device(struct cx18_stream *s,
+					    struct cx18_mdl *mdl)
+{
+	if (list_is_singular(&mdl->buf_list))
+		cx18_buf_sync_for_device(s, list_first_entry(&mdl->buf_list,
+							     struct cx18_buffer,
+							     list));
+	else
+		_cx18_mdl_sync_for_device(s, mdl);
+}
+
 void cx18_buf_swap(struct cx18_buffer *buf);
+void _cx18_mdl_swap(struct cx18_mdl *mdl);
+
+static inline void cx18_mdl_swap(struct cx18_mdl *mdl)
+{
+	if (list_is_singular(&mdl->buf_list))
+		cx18_buf_swap(list_first_entry(&mdl->buf_list,
+					       struct cx18_buffer, list));
+	else
+		_cx18_mdl_swap(mdl);
+}
 
 /* cx18_queue utility functions */
-struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
+struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_mdl *mdl,
 				 struct cx18_queue *q, int to_front);
 
 static inline
-struct cx18_queue *cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
+struct cx18_queue *cx18_enqueue(struct cx18_stream *s, struct cx18_mdl *mdl,
 				struct cx18_queue *q)
 {
-	return _cx18_enqueue(s, buf, q, 0); /* FIFO */
+	return _cx18_enqueue(s, mdl, q, 0); /* FIFO */
 }
 
 static inline
-struct cx18_queue *cx18_push(struct cx18_stream *s, struct cx18_buffer *buf,
+struct cx18_queue *cx18_push(struct cx18_stream *s, struct cx18_mdl *mdl,
 			     struct cx18_queue *q)
 {
-	return _cx18_enqueue(s, buf, q, 1); /* LIFO */
+	return _cx18_enqueue(s, mdl, q, 1); /* LIFO */
 }
 
 void cx18_queue_init(struct cx18_queue *q);
-struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q);
-struct cx18_buffer *cx18_queue_get_buf(struct cx18_stream *s, u32 id,
+struct cx18_mdl *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q);
+struct cx18_mdl *cx18_queue_get_mdl(struct cx18_stream *s, u32 id,
 	u32 bytesused);
 void cx18_flush_queues(struct cx18_stream *s);
 
+/* queue MDL reconfiguration helpers */
+void cx18_unload_queues(struct cx18_stream *s);
+void cx18_load_queues(struct cx18_stream *s);
+
 /* cx18_stream utility functions */
 int cx18_stream_alloc(struct cx18_stream *s);
 void cx18_stream_free(struct cx18_stream *s);

drivers/media/video/cx18/cx18-streams.c

@@ -115,6 +115,9 @@ static void cx18_stream_init(struct cx18 *cx, int type)
 	s->dma = cx18_stream_info[type].dma;
 	s->buffers = cx->stream_buffers[type];
 	s->buf_size = cx->stream_buf_size[type];
+	INIT_LIST_HEAD(&s->buf_pool);
+	s->bufs_per_mdl = 1;
+	s->mdl_size = s->buf_size * s->bufs_per_mdl;
 
 	init_waitqueue_head(&s->waitq);
 	s->id = -1;
@@ -124,6 +127,8 @@ static void cx18_stream_init(struct cx18 *cx, int type)
 	cx18_queue_init(&s->q_busy);
 	spin_lock_init(&s->q_full.lock);
 	cx18_queue_init(&s->q_full);
+	spin_lock_init(&s->q_idle.lock);
+	cx18_queue_init(&s->q_idle);
 
 	INIT_WORK(&s->out_work_order, cx18_out_work_handler);
 }
@@ -441,8 +446,8 @@ static void cx18_vbi_setup(struct cx18_stream *s)
 }
 
 static
-struct cx18_queue *_cx18_stream_put_buf_fw(struct cx18_stream *s,
-					   struct cx18_buffer *buf)
+struct cx18_queue *_cx18_stream_put_mdl_fw(struct cx18_stream *s,
+					   struct cx18_mdl *mdl)
 {
 	struct cx18 *cx = s->cx;
 	struct cx18_queue *q;
@@ -451,16 +456,16 @@ struct cx18_queue *_cx18_stream_put_buf_fw(struct cx18_stream *s,
 	if (s->handle == CX18_INVALID_TASK_HANDLE ||
 	    test_bit(CX18_F_S_STOPPING, &s->s_flags) ||
 	    !test_bit(CX18_F_S_STREAMING, &s->s_flags))
-		return cx18_enqueue(s, buf, &s->q_free);
+		return cx18_enqueue(s, mdl, &s->q_free);
 
-	q = cx18_enqueue(s, buf, &s->q_busy);
+	q = cx18_enqueue(s, mdl, &s->q_busy);
 	if (q != &s->q_busy)
-		return q; /* The firmware has the max buffers it can handle */
+		return q; /* The firmware has the max MDLs it can handle */
 
-	cx18_buf_sync_for_device(s, buf);
+	cx18_mdl_sync_for_device(s, mdl);
 	cx18_vapi(cx, CX18_CPU_DE_SET_MDL, 5, s->handle,
-		  (void __iomem *) &cx->scb->cpu_mdl[buf->id] - cx->enc_mem,
-		  1, buf->id, s->buf_size);
+		  (void __iomem *) &cx->scb->cpu_mdl[mdl->id] - cx->enc_mem,
+		  s->bufs_per_mdl, mdl->id, s->mdl_size);
 	return q;
 }
 
@@ -468,7 +473,7 @@ static
 void _cx18_stream_load_fw_queue(struct cx18_stream *s)
 {
 	struct cx18_queue *q;
-	struct cx18_buffer *buf;
+	struct cx18_mdl *mdl;
 
 	if (atomic_read(&s->q_free.depth) == 0 ||
 	    atomic_read(&s->q_busy.depth) >= CX18_MAX_FW_MDLS_PER_STREAM)
@@ -476,10 +481,10 @@ void _cx18_stream_load_fw_queue(struct cx18_stream *s)
 
 	/* Move from q_free to q_busy notifying the firmware, until the limit */
 	do {
-		buf = cx18_dequeue(s, &s->q_free);
-		if (buf == NULL)
+		mdl = cx18_dequeue(s, &s->q_free);
+		if (mdl == NULL)
 			break;
-		q = _cx18_stream_put_buf_fw(s, buf);
+		q = _cx18_stream_put_mdl_fw(s, mdl);
 	} while (atomic_read(&s->q_busy.depth) < CX18_MAX_FW_MDLS_PER_STREAM
 		 && q == &s->q_busy);
 }
@@ -492,11 +497,21 @@ void cx18_out_work_handler(struct work_struct *work)
 	_cx18_stream_load_fw_queue(s);
 }
 
+static void cx18_stream_configure_mdls(struct cx18_stream *s)
+{
+	cx18_unload_queues(s);
+
+	/* For now */
+	s->bufs_per_mdl = 1;
+	s->mdl_size = s->buf_size * s->bufs_per_mdl;
+
+	cx18_load_queues(s);
+}
+
 int cx18_start_v4l2_encode_stream(struct cx18_stream *s)
 {
 	u32 data[MAX_MB_ARGUMENTS];
 	struct cx18 *cx = s->cx;
-	struct cx18_buffer *buf;
 	int captype = 0;
 	struct cx18_api_func_private priv;
 
@@ -619,14 +634,7 @@ int cx18_start_v4l2_encode_stream(struct cx18_stream *s)
 		(void __iomem *)&cx->scb->cpu_mdl_ack[s->type][1] - cx->enc_mem);
 
 	/* Init all the cpu_mdls for this stream */
-	cx18_flush_queues(s);
-	spin_lock(&s->q_free.lock);
-	list_for_each_entry(buf, &s->q_free.list, list) {
-		cx18_writel(cx, buf->dma_handle,
-					&cx->scb->cpu_mdl[buf->id].paddr);
-		cx18_writel(cx, s->buf_size, &cx->scb->cpu_mdl[buf->id].length);
-	}
-	spin_unlock(&s->q_free.lock);
+	cx18_stream_configure_mdls(s);
 	_cx18_stream_load_fw_queue(s);
 
 	/* begin_capture */

drivers/media/video/cx18/cx18-streams.h

@@ -28,18 +28,18 @@ int cx18_streams_setup(struct cx18 *cx);
 int cx18_streams_register(struct cx18 *cx);
 void cx18_streams_cleanup(struct cx18 *cx, int unregister);
 
-/* Related to submission of buffers to firmware */
+/* Related to submission of mdls to firmware */
 static inline void cx18_stream_load_fw_queue(struct cx18_stream *s)
 {
 	struct cx18 *cx = s->cx;
 	queue_work(cx->out_work_queue, &s->out_work_order);
 }
 
-static inline void cx18_stream_put_buf_fw(struct cx18_stream *s,
-					  struct cx18_buffer *buf)
+static inline void cx18_stream_put_mdl_fw(struct cx18_stream *s,
+					  struct cx18_mdl *mdl)
 {
-	/* Put buf on q_free; the out work handler will move buf(s) to q_busy */
-	cx18_enqueue(s, buf, &s->q_free);
+	/* Put mdl on q_free; the out work handler will move mdl(s) to q_busy */
+	cx18_enqueue(s, mdl, &s->q_free);
 	cx18_stream_load_fw_queue(s);
 }
 

drivers/media/video/cx18/cx18-vbi.c

@@ -105,6 +105,7 @@ static void copy_vbi_data(struct cx18 *cx, int lines, u32 pts_stamp)
 
 /* Compress raw VBI format, removes leading SAV codes and surplus space
    after the frame.  Returns new compressed size. */
+/* FIXME - this function ignores the input size. */
 static u32 compress_raw_buf(struct cx18 *cx, u8 *buf, u32 size, u32 hdr_size)
 {
 	u32 line_size = vbi_active_samples;
@@ -185,8 +186,7 @@ static u32 compress_sliced_buf(struct cx18 *cx, u8 *buf, u32 size,
 	return line;
 }
 
-void cx18_process_vbi_data(struct cx18 *cx, struct cx18_buffer *buf,
-			   int streamtype)
+static void _cx18_process_vbi_data(struct cx18 *cx, struct cx18_buffer *buf)
 {
 	/*
 	 * The CX23418 provides a 12 byte header in its raw VBI buffers to us:
@@ -203,9 +203,6 @@ void cx18_process_vbi_data(struct cx18 *cx, struct cx18_buffer *buf,
 	u32 pts;
 	int lines;
 
-	if (streamtype != CX18_ENC_STREAM_TYPE_VBI)
-		return;
-
 	/*
 	 * The CX23418 sends us data that is 32 bit little-endian swapped,
 	 * but we want the raw VBI bytes in the order they were in the raster
@@ -250,3 +247,31 @@ void cx18_process_vbi_data(struct cx18 *cx, struct cx18_buffer *buf,
 		copy_vbi_data(cx, lines, pts);
 	cx->vbi.frame++;
 }
+
+void cx18_process_vbi_data(struct cx18 *cx, struct cx18_mdl *mdl,
+			   int streamtype)
+{
+	struct cx18_buffer *buf;
+	u32 orig_used;
+
+	if (streamtype != CX18_ENC_STREAM_TYPE_VBI)
+		return;
+
+	/*
+	 * Big assumption here:
+	 * Every buffer hooked to the MDL's buf_list is a complete VBI frame
+	 * that ends at the end of the buffer.
+	 *
+	 * To assume anything else would make the code in this file
+	 * more complex, or require extra memcpy()'s to make the
+	 * buffers satisfy the above assumption.  It's just simpler to set
+	 * up the encoder buffer transfers to make the assumption true.
+	 */
+	list_for_each_entry(buf, &mdl->buf_list, list) {
+		orig_used = buf->bytesused;
+		if (orig_used == 0)
+			break;
+		_cx18_process_vbi_data(cx, buf);
+		mdl->bytesused -= (orig_used - buf->bytesused);
+	}
+}

drivers/media/video/cx18/cx18-vbi.h

@@ -21,6 +21,6 @@
  *  02111-1307  USA
  */
 
-void cx18_process_vbi_data(struct cx18 *cx, struct cx18_buffer *buf,
+void cx18_process_vbi_data(struct cx18 *cx, struct cx18_mdl *mdl,
 			   int streamtype);
 int cx18_used_line(struct cx18 *cx, int line, int field);