staging: bcm2835-camera: Remove V4L2/MMAL buffer remapping

The MMAL and V4L2 buffers had been disassociated, and linked on
demand.  Seeing as both are finite and low in number, and we now have
the same number of each, link them for the duration.  This removes the
complexity of maintaining lists as the struct mmal_buffer context
comes back from the VPU, so we can directly link back to the relevant
V4L2 buffer.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c

@@ -299,8 +299,8 @@ static int buffer_prepare(struct vb2_buffer *vb)
 	struct bm2835_mmal_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 	unsigned long size;
 
-	v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev, "%s: dev:%p\n",
-		 __func__, dev);
+	v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev, "%s: dev:%p, vb %p\n",
+		 __func__, dev, vb);
 
 	BUG_ON(!dev->capture.port);
 	BUG_ON(!dev->capture.fmt);
@@ -492,7 +492,8 @@ static void buffer_queue(struct vb2_buffer *vb)
 	int ret;
 
 	v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev,
-		 "%s: dev:%p buf:%p\n", __func__, dev, buf);
+		 "%s: dev:%p buf:%p, idx %u\n",
+		 __func__, dev, buf, vb2->vb2_buf.index);
 
 	ret = vchiq_mmal_submit_buffer(dev->instance, dev->capture.port, buf);
 	if (ret < 0)

drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c

@@ -326,16 +326,12 @@ static int bulk_receive(struct vchiq_mmal_instance *instance,
 			struct mmal_msg_context *msg_context)
 {
 	unsigned long rd_len;
-	unsigned long flags = 0;
 	int ret;
 
 	rd_len = msg->u.buffer_from_host.buffer_header.length;
 
-	/* take buffer from queue */
-	spin_lock_irqsave(&msg_context->u.bulk.port->slock, flags);
-	if (list_empty(&msg_context->u.bulk.port->buffers)) {
-		spin_unlock_irqrestore(&msg_context->u.bulk.port->slock, flags);
-		pr_err("buffer list empty trying to submit bulk receive\n");
+	if (!msg_context->u.bulk.buffer) {
+		pr_err("bulk.buffer not configured - error in buffer_from_host\n");
 
 		/* todo: this is a serious error, we should never have
 		 * committed a buffer_to_host operation to the mmal
@@ -350,13 +346,6 @@ static int bulk_receive(struct vchiq_mmal_instance *instance,
 		return -EINVAL;
 	}
 
-	msg_context->u.bulk.buffer =
-	    list_entry(msg_context->u.bulk.port->buffers.next,
-		       struct mmal_buffer, list);
-	list_del(&msg_context->u.bulk.buffer->list);
-
-	spin_unlock_irqrestore(&msg_context->u.bulk.port->slock, flags);
-
 	/* ensure we do not overrun the available buffer */
 	if (rd_len > msg_context->u.bulk.buffer->buffer_size) {
 		rd_len = msg_context->u.bulk.buffer->buffer_size;
@@ -419,31 +408,6 @@ static int inline_receive(struct vchiq_mmal_instance *instance,
 			  struct mmal_msg *msg,
 			  struct mmal_msg_context *msg_context)
 {
-	unsigned long flags = 0;
-
-	/* take buffer from queue */
-	spin_lock_irqsave(&msg_context->u.bulk.port->slock, flags);
-	if (list_empty(&msg_context->u.bulk.port->buffers)) {
-		spin_unlock_irqrestore(&msg_context->u.bulk.port->slock, flags);
-		pr_err("buffer list empty trying to receive inline\n");
-
-		/* todo: this is a serious error, we should never have
-		 * committed a buffer_to_host operation to the mmal
-		 * port without the buffer to back it up (with
-		 * underflow handling) and there is no obvious way to
-		 * deal with this. Less bad than the bulk case as we
-		 * can just drop this on the floor but...unhelpful
-		 */
-		return -EINVAL;
-	}
-
-	msg_context->u.bulk.buffer =
-	    list_entry(msg_context->u.bulk.port->buffers.next,
-		       struct mmal_buffer, list);
-	list_del(&msg_context->u.bulk.buffer->list);
-
-	spin_unlock_irqrestore(&msg_context->u.bulk.port->slock, flags);
-
 	memcpy(msg_context->u.bulk.buffer->buffer,
 	       msg->u.buffer_from_host.short_data,
 	       msg->u.buffer_from_host.payload_in_message);
@@ -463,6 +427,9 @@ buffer_from_host(struct vchiq_mmal_instance *instance,
 	struct mmal_msg m;
 	int ret;
 
+	if (!port->enabled)
+		return -EINVAL;
+
 	pr_debug("instance:%p buffer:%p\n", instance->handle, buf);
 
 	/* get context */
@@ -476,7 +443,7 @@ buffer_from_host(struct vchiq_mmal_instance *instance,
 	/* store bulk message context for when data arrives */
 	msg_context->u.bulk.instance = instance;
 	msg_context->u.bulk.port = port;
-	msg_context->u.bulk.buffer = NULL;	/* not valid until bulk xfer */
+	msg_context->u.bulk.buffer = buf;
 	msg_context->u.bulk.buffer_used = 0;
 
 	/* initialise work structure ready to schedule callback */
@@ -526,43 +493,6 @@ buffer_from_host(struct vchiq_mmal_instance *instance,
 	return ret;
 }
 
-/* submit a buffer to the mmal sevice
- *
- * the buffer_from_host uses size data from the ports next available
- * mmal_buffer and deals with there being no buffer available by
- * incrementing the underflow for later
- */
-static int port_buffer_from_host(struct vchiq_mmal_instance *instance,
-				 struct vchiq_mmal_port *port)
-{
-	int ret;
-	struct mmal_buffer *buf;
-	unsigned long flags = 0;
-
-	if (!port->enabled)
-		return -EINVAL;
-
-	/* peek buffer from queue */
-	spin_lock_irqsave(&port->slock, flags);
-	if (list_empty(&port->buffers)) {
-		spin_unlock_irqrestore(&port->slock, flags);
-		return -ENOSPC;
-	}
-
-	buf = list_entry(port->buffers.next, struct mmal_buffer, list);
-
-	spin_unlock_irqrestore(&port->slock, flags);
-
-	/* issue buffer to mmal service */
-	ret = buffer_from_host(instance, port, buf);
-	if (ret) {
-		pr_err("adding buffer header failed\n");
-		/* todo: how should this be dealt with */
-	}
-
-	return ret;
-}
-
 /* deals with receipt of buffer to host message */
 static void buffer_to_host_cb(struct vchiq_mmal_instance *instance,
 			      struct mmal_msg *msg, u32 msg_len)
@@ -1420,7 +1350,14 @@ static int port_disable(struct vchiq_mmal_instance *instance,
 	ret = port_action_port(instance, port,
 			       MMAL_MSG_PORT_ACTION_TYPE_DISABLE);
 	if (ret == 0) {
-		/* drain all queued buffers on port */
+		/*
+		 * Drain all queued buffers on port. This should only
+		 * apply to buffers that have been queued before the port
+		 * has been enabled. If the port has been enabled and buffers
+		 * passed, then the buffers should have been removed from this
+		 * list, and we should get the relevant callbacks via VCHIQ
+		 * to release the buffers.
+		 */
 		spin_lock_irqsave(&port->slock, flags);
 
 		list_for_each_safe(buf_head, q, &port->buffers) {
@@ -1449,7 +1386,7 @@ static int port_enable(struct vchiq_mmal_instance *instance,
 		       struct vchiq_mmal_port *port)
 {
 	unsigned int hdr_count;
-	struct list_head *buf_head;
+	struct list_head *q, *buf_head;
 	int ret;
 
 	if (port->enabled)
@@ -1475,7 +1412,7 @@ static int port_enable(struct vchiq_mmal_instance *instance,
 	if (port->buffer_cb) {
 		/* send buffer headers to videocore */
 		hdr_count = 1;
-		list_for_each(buf_head, &port->buffers) {
+		list_for_each_safe(buf_head, q, &port->buffers) {
 			struct mmal_buffer *mmalbuf;
 
 			mmalbuf = list_entry(buf_head, struct mmal_buffer,
@@ -1484,6 +1421,7 @@ static int port_enable(struct vchiq_mmal_instance *instance,
 			if (ret)
 				goto done;
 
+			list_del(buf_head);
 			hdr_count++;
 			if (hdr_count > port->current_buffer.num)
 				break;
@@ -1696,12 +1634,15 @@ int vchiq_mmal_submit_buffer(struct vchiq_mmal_instance *instance,
 			     struct mmal_buffer *buffer)
 {
 	unsigned long flags = 0;
+	int ret;
 
-	spin_lock_irqsave(&port->slock, flags);
-	list_add_tail(&buffer->list, &port->buffers);
-	spin_unlock_irqrestore(&port->slock, flags);
-
-	port_buffer_from_host(instance, port);
+	ret = buffer_from_host(instance, port, buffer);
+	if (ret == -EINVAL) {
+		/* Port is disabled. Queue for when it is enabled. */
+		spin_lock_irqsave(&port->slock, flags);
+		list_add_tail(&buffer->list, &port->buffers);
+		spin_unlock_irqrestore(&port->slock, flags);
+	}
 
 	return 0;
 }