diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
index ccc5cdc008c..b559a9c2f85 100644
--- a/drivers/staging/comedi/comedi.h
+++ b/drivers/staging/comedi/comedi.h
@@ -451,7 +451,7 @@
 
 #define COMEDI_CB_EOS		1	/* end of scan */
 #define COMEDI_CB_EOA		2	/* end of acquisition */
-#define COMEDI_CB_BLOCK		4	/* DEPRECATED: convenient block size */
+#define COMEDI_CB_BLOCK		4	/* data has arrived: wakes up read() / write() */
 #define COMEDI_CB_EOBUF		8	/* DEPRECATED: end of buffer */
 #define COMEDI_CB_ERROR		16	/* card error during acquisition */
 #define COMEDI_CB_OVERFLOW	32	/* buffer overflow/underflow */