ieee80211: document DS bit usage
I keep needing this because I'm too stupid to remember it.
Everybody else can probably remember, but who knows :)
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index b1bb817..382387e 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -18,6 +18,22 @@
#include <linux/types.h>
#include <asm/byteorder.h>
+/*
+ * DS bit usage
+ *
+ * TA = transmitter address
+ * RA = receiver address
+ * DA = destination address
+ * SA = source address
+ *
+ * ToDS FromDS A1(RA) A2(TA) A3 A4 Use
+ * -----------------------------------------------------------------
+ * 0 0 DA SA BSSID - IBSS/DLS
+ * 0 1 DA BSSID SA - AP -> STA
+ * 1 0 BSSID SA DA - AP <- STA
+ * 1 1 RA TA DA SA unspecified (WDS)
+ */
+
#define FCS_LEN 4
#define IEEE80211_FCTL_VERS 0x0003