2 files changed, 22 insertions, 7 deletions

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 8f8c8eeaf046..0cf86bcbeea2 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -46,6 +46,11 @@
 
 #include "core.h"
 
+/*
+ * ABI version history is documented in linux/firewire-cdev.h.
+ */
+#define FW_CDEV_KERNEL_VERSION 3
+
 struct client {
         u32 version;
         struct fw_device *device;
@@ -395,7 +400,7 @@ static int ioctl_get_info(struct client *client, union ioctl_arg *arg)
         unsigned long ret = 0;
 
         client->version = a->version;
-        a->version = FW_CDEV_VERSION;
+        a->version = FW_CDEV_KERNEL_VERSION;
         a->card = client->device->card->index;
 
         down_read(&fw_device_rwsem);
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 6ffb24a1f2f2..0d0cc07358af 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -219,7 +219,7 @@ union fw_cdev_event {
         struct fw_cdev_event_response           response;
         struct fw_cdev_event_request            request;
         struct fw_cdev_event_iso_interrupt      iso_interrupt;
-        struct fw_cdev_event_iso_resource       iso_resource;
+        struct fw_cdev_event_iso_resource       iso_resource; /* added in 2.6.30 */
 };
 
 /* available since kernel version 2.6.22 */
@@ -252,22 +252,32 @@ union fw_cdev_event {
 #define FW_CDEV_IOC_GET_CYCLE_TIMER2   _IOWR('#', 0x14, struct fw_cdev_get_cycle_timer2)
 
 /*
- * FW_CDEV_VERSION History
+ * ABI version history
  *  1  (2.6.22)  - initial version
+ *     (2.6.24)  - added %FW_CDEV_IOC_GET_CYCLE_TIMER
  *  2  (2.6.30)  - changed &fw_cdev_event_iso_interrupt.header if
  *                 &fw_cdev_create_iso_context.header_size is 8 or more
+ *               - added %FW_CDEV_IOC_*_ISO_RESOURCE*,
+ *                 %FW_CDEV_IOC_GET_SPEED, %FW_CDEV_IOC_SEND_BROADCAST_REQUEST,
+ *                 %FW_CDEV_IOC_SEND_STREAM_PACKET
  *     (2.6.32)  - added time stamp to xmit &fw_cdev_event_iso_interrupt
  *     (2.6.33)  - IR has always packet-per-buffer semantics now, not one of
  *                 dual-buffer or packet-per-buffer depending on hardware
  *  3  (2.6.34)  - made &fw_cdev_get_cycle_timer reliable
+ *               - added %FW_CDEV_IOC_GET_CYCLE_TIMER2
  */
-#define FW_CDEV_VERSION 3
+#define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */
 
 /**
  * struct fw_cdev_get_info - General purpose information ioctl
- * @version:    The version field is just a running serial number.
- *              We never break backwards compatibility, but may add more
- *              structs and ioctls in later revisions.
+ * @version:    The version field is just a running serial number.  Both an
+ *              input parameter (ABI version implemented by the client) and
+ *              output parameter (ABI version implemented by the kernel).
+ *              A client must not fill in an %FW_CDEV_VERSION defined from an
+ *              included kernel header file but the actual version for which
+ *              the client was implemented.  This is necessary for forward
+ *              compatibility.  We never break backwards compatibility, but
+ *              may add more structs, events, and ioctls in later revisions.
  * @rom_length: If @rom is non-zero, at most rom_length bytes of configuration
  *              ROM will be copied into that user space address.  In either
  *              case, @rom_length is updated with the actual length of the