diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index acb042c3e034..de850f3fd49d 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -445,9 +445,10 @@ int comedi_buf_get(struct comedi_subdevice *s, unsigned short *x)
 }
 EXPORT_SYMBOL_GPL(comedi_buf_get);
 
-void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
+void comedi_buf_memcpy_to(struct comedi_subdevice *s, unsigned int offset,
 			  const void *data, unsigned int num_bytes)
 {
+	struct comedi_async *async = s->async;
 	unsigned int write_ptr = async->buf_write_ptr + offset;
 
 	if (write_ptr >= async->prealloc_bufsz)
diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
index d19a20ca91b7..221db717ebc4 100644
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -346,7 +346,7 @@ unsigned int comedi_buf_read_free(struct comedi_async *, unsigned int);
 int comedi_buf_put(struct comedi_subdevice *s, unsigned short x);
 int comedi_buf_get(struct comedi_subdevice *s, unsigned short *x);
 
-void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
+void comedi_buf_memcpy_to(struct comedi_subdevice *s, unsigned int offset,
 			  const void *source, unsigned int num_bytes);
 void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
 			    void *destination, unsigned int num_bytes);
diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
index 9b8851c7e072..51095bebc087 100644
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3200.c
@@ -2712,7 +2712,7 @@ static int i_APCI3200_InterruptHandleEos(struct comedi_device *dev)
 				s->async->events |= COMEDI_CB_ERROR;
 			}
 			/*  Write all 7 scan values in the comedi buffer */
-			comedi_buf_memcpy_to(s->async, 0,
+			comedi_buf_memcpy_to(s, 0,
 				(unsigned int *) s_BoardInfos[dev->minor].
 				ui_ScanValueArray, (7 + 12) * sizeof(unsigned int));
 
diff --git a/drivers/staging/comedi/drivers/comedi_fc.c b/drivers/staging/comedi/drivers/comedi_fc.c
index 9d9b1469e89a..81749a778de0 100644
--- a/drivers/staging/comedi/drivers/comedi_fc.c
+++ b/drivers/staging/comedi/drivers/comedi_fc.c
@@ -74,7 +74,7 @@ unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *s,
 		return 0;
 	}
 
-	comedi_buf_memcpy_to(async, 0, data, num_bytes);
+	comedi_buf_memcpy_to(s, 0, data, num_bytes);
 	comedi_buf_write_free(async, num_bytes);
 	cfc_inc_scan_progress(s, num_bytes);
 	async->events |= COMEDI_CB_BLOCK;