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Commit e14296ca authored by Bruno Randolf's avatar Bruno Randolf Committed by John W. Linville
Browse files

ath5k: add notes about rx timestamp 



add comments about the fact that we don't know when exactly the atheros
hardware takes the RX timestamp.

drivers/net/wireless/ath5k/base.c:      Changes-licensed-under: 3-Clause-BSD

Signed-off-by: default avatarBruno Randolf <bruno@thinktube.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent b47f407b

drivers/net/wireless/ath5k/base.c

+11 −0
Original line number Diff line number Diff line
@@ -1844,6 +1844,17 @@ accept: 
		 * 15bit only. that means TSF extension has to be done within

		 * 32768usec (about 32ms). it might be necessary to move this to

		 * the interrupt handler, like it is done in madwifi.

		 *

		 * Unfortunately we don't know when the hardware takes the rx

		 * timestamp (beginning of phy frame, data frame, end of rx?).

		 * The only thing we know is that it is hardware specific...

		 * On AR5213 it seems the rx timestamp is at the end of the

		 * frame, but i'm not sure.

		 *

		 * NOTE: mac80211 defines mactime at the beginning of the first

		 * data symbol. Since we don't have any time references it's

		 * impossible to comply to that. This affects IBSS merge only

		 * right now, so it's not too bad...

		 */

		rxs.mactime = ath5k_extend_tsf(sc->ah, rs.rs_tstamp);

		rxs.flag |= RX_FLAG_TSFT;