[media] vb2: add thread support

In order to implement vb2 DVB support you need to be able to start
a kernel thread that queues and dequeues buffers, calling a callback
function for every buffer. This patch adds support for that.

It's based on drivers/media/v4l2-core/videobuf-dvb.c, but with all the DVB
specific stuff stripped out, thus making it much more generic.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index b1859f6953b2..46e76096c22a 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -20,6 +20,7 @@
 
 struct vb2_alloc_ctx;
 struct vb2_fileio_data;
+struct vb2_threadio_data;
 
 /**
  * struct vb2_mem_ops - memory handling/memory allocator operations
@@ -375,6 +376,7 @@ struct v4l2_fh;
  * @start_streaming_called: start_streaming() was called successfully and we
  *              started streaming.
  * @fileio:     file io emulator internal data, used only if emulator is active
+ * @threadio:   thread io internal data, used only if thread is active
  */
 struct vb2_queue {
         enum v4l2_buf_type              type;
@@ -411,6 +413,7 @@ struct vb2_queue {
         unsigned int                    start_streaming_called:1;
 
         struct vb2_fileio_data          *fileio;
+        struct vb2_threadio_data        *threadio;
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
         /*
@@ -461,6 +464,35 @@ size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
                 loff_t *ppos, int nonblock);
 size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
                 loff_t *ppos, int nonblock);
+/**
+ * vb2_thread_fnc - callback function for use with vb2_thread
+ *
+ * This is called whenever a buffer is dequeued in the thread.
+ */
+typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv);
+
+/**
+ * vb2_thread_start() - start a thread for the given queue.
+ * @q:          videobuf queue
+ * @fnc:        callback function
+ * @priv:       priv pointer passed to the callback function
+ * @thread_name:the name of the thread. This will be prefixed with "vb2-".
+ *
+ * This starts a thread that will queue and dequeue until an error occurs
+ * or @vb2_thread_stop is called.
+ *
+ * This function should not be used for anything else but the videobuf2-dvb
+ * support. If you think you have another good use-case for this, then please
+ * contact the linux-media mailinglist first.
+ */
+int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
+                     const char *thread_name);
+
+/**
+ * vb2_thread_stop() - stop the thread for the given queue.
+ * @q:          videobuf queue
+ */
+int vb2_thread_stop(struct vb2_queue *q);
 
 /**
  * vb2_is_streaming() - return streaming status of the queue