diff --git a/sys/alpha/include/bus.h b/sys/alpha/include/bus.h
index 8c6d3240b28..4fe12862b68 100644
--- a/sys/alpha/include/bus.h
+++ b/sys/alpha/include/bus.h
@@ -569,6 +569,10 @@ typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
  *	nsegments:	Number of discontinuities allowed in maps.
  *	maxsegsz:	Maximum size of a segment in the map.
  *	flags:		Bus DMA flags.
+ *	lockfunc:	An optional function to handle driver-defined lock
+ *			operations.
+ *	lockfuncarg:	An argument that will be passed to lockfunc in addition
+ *			to the lock operation.
  *	dmat:		A pointer to set to a valid dma tag should the return
  *			value of this function indicate success.
  */
diff --git a/sys/amd64/include/bus_dma.h b/sys/amd64/include/bus_dma.h
index b9129e97cf5..4399c6f9c92 100644
--- a/sys/amd64/include/bus_dma.h
+++ b/sys/amd64/include/bus_dma.h
@@ -160,6 +160,10 @@ typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
  *	nsegments:	Number of discontinuities allowed in maps.
  *	maxsegsz:	Maximum size of a segment in the map.
  *	flags:		Bus DMA flags.
+ *	lockfunc:	An optional function to handle driver-defined lock
+ *			operations.
+ *	lockfuncarg:	An argument that will be passed to lockfunc in addition
+ *			to the lock operation.
  *	dmat:		A pointer to set to a valid dma tag should the return
  *			value of this function indicate success.
  */
diff --git a/sys/i386/include/bus_dma.h b/sys/i386/include/bus_dma.h
index 6d9db77120b..a278f62f78b 100644
--- a/sys/i386/include/bus_dma.h
+++ b/sys/i386/include/bus_dma.h
@@ -160,6 +160,10 @@ typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
  *	nsegments:	Number of discontinuities allowed in maps.
  *	maxsegsz:	Maximum size of a segment in the map.
  *	flags:		Bus DMA flags.
+ *	lockfunc:	An optional function to handle driver-defined lock
+ *			operations.
+ *	lockfuncarg:	An argument that will be passed to lockfunc in addition
+ *			to the lock operation.
  *	dmat:		A pointer to set to a valid dma tag should the return
  *			value of this function indicate success.
  */
diff --git a/sys/ia64/include/bus.h b/sys/ia64/include/bus.h
index 9c9ae36c3a6..e8e75745329 100644
--- a/sys/ia64/include/bus.h
+++ b/sys/ia64/include/bus.h
@@ -940,6 +940,10 @@ typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
  *	nsegments:	Number of discontinuities allowed in maps.
  *	maxsegsz:	Maximum size of a segment in the map.
  *	flags:		Bus DMA flags.
+ *	lockfunc:	An optional function to handle driver-defined lock
+ *			operations.
+ *	lockfuncarg:	An argument that will be passed to lockfunc in addition
+ *			to the lock operation.
  *	dmat:		A pointer to set to a valid dma tag should the return
  *			value of this function indicate success.
  */
diff --git a/sys/sys/bus_dma.h b/sys/sys/bus_dma.h
index 6d9db77120b..a278f62f78b 100644
--- a/sys/sys/bus_dma.h
+++ b/sys/sys/bus_dma.h
@@ -160,6 +160,10 @@ typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
  *	nsegments:	Number of discontinuities allowed in maps.
  *	maxsegsz:	Maximum size of a segment in the map.
  *	flags:		Bus DMA flags.
+ *	lockfunc:	An optional function to handle driver-defined lock
+ *			operations.
+ *	lockfuncarg:	An argument that will be passed to lockfunc in addition
+ *			to the lock operation.
  *	dmat:		A pointer to set to a valid dma tag should the return
  *			value of this function indicate success.
  */