rt2x00: Don't overwrite beacon buffers in pairwise key setup

rt2800 devices use parts of the pariwise key table to store the beacon
frames for beacon 6 and 7. To not overwrite the beacon frame buffers
limit the number of entries we store in the pairwise key table to 222.

Also add some descriptive comments about this shared memory usage.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2800.h b/drivers/net/wireless/rt2x00/rt2800.h
index 2edc7742a7e9..e1583cf5894b 100644
--- a/drivers/net/wireless/rt2x00/rt2800.h
+++ b/drivers/net/wireless/rt2x00/rt2800.h
@@ -1435,6 +1435,24 @@
 
 /*
  * Security key table memory.
+ *
+ * The pairwise key table shares some memory with the beacon frame
+ * buffers 6 and 7. That basically means that when beacon 6 & 7
+ * are used we should only use the reduced pairwise key table which
+ * has a maximum of 222 entries.
+ *
+ * ---------------------------------------------
+ * |0x4000 | Pairwise Key   | Reduced Pairwise |
+ * |       | Table          | Key Table        |
+ * |       | Size: 256 * 32 | Size: 222 * 32   |
+ * |0x5BC0 |                |-------------------
+ * |       |                | Beacon 6         |
+ * |0x5DC0 |                |-------------------
+ * |       |                | Beacon 7         |
+ * |0x5FC0 |                |-------------------
+ * |0x5FFF |                |
+ * --------------------------
+ *
  * MAC_WCID_BASE: 8-bytes (use only 6 bytes) * 256 entry
  * PAIRWISE_KEY_TABLE_BASE: 32-byte * 256 entry
  * MAC_IVEIV_TABLE_BASE: 8-byte * 256-entry
@@ -1584,7 +1602,8 @@ struct mac_iveiv_entry {
  * 2. Extract memory from FCE table for BCN 4~5
  * 3. Extract memory from Pair-wise key table for BCN 6~7
  *    It occupied those memory of wcid 238~253 for BCN 6
- *    and wcid 222~237 for BCN 7
+ *    and wcid 222~237 for BCN 7 (see Security key table memory
+ *    for more info).
  *
  * IMPORTANT NOTE: Not sure why legacy driver does this,
  * but HW_BEACON_BASE7 is 0x0200 bytes below HW_BEACON_BASE6.