+
+/**
+ * vb2_core_reqbufs() - Initiate streaming
+ * @q: videobuf2 queue
+ * @memory: memory type
+ * @count: requested buffer count
+ *
+ * Should be called from vidioc_reqbufs ioctl handler of a driver.
+ *
+ * This function:
+ *
+ * #) verifies streaming parameters passed from the userspace,
+ * #) sets up the queue,
+ * #) negotiates number of buffers and planes per buffer with the driver
+ * to be used during streaming,
+ * #) allocates internal buffer structures (struct vb2_buffer), according to
+ * the agreed parameters,
+ * #) for MMAP memory type, allocates actual video memory, using the
+ * memory handling/allocation routines provided during queue initialization
+ *
+ * If req->count is 0, all the memory will be freed instead.
+ * If the queue has been allocated previously (by a previous vb2_reqbufs) call
+ * and the queue is not busy, memory will be reallocated.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_reqbufs handler in driver.
+ */