On Monday 04 May 2009, Johannes Berg wrote: > On Mon, 2009-05-04 at 17:29 +0200, Ivo van Doorn wrote: > > Hi, > > > > Just as side information for other readers: > > > > Alexandre is looking into the problem of rt2500usb/rt73usb and > > possibly other USB drivers, that they cannot report the ACK status > > of frames to mac80211 which is problematic for hostapd. > > I realise that this probably doesn't help and is tangential to the > question being asked, but I do not think processing ACK frames in > software is possible for this, since the software does not know which > frame was transmitted, due to four queues being used, and retries etc. Well I believe the idea would be that (I'll see if I can dig up a reference to the initial discussion about this feature on this list) the driver sets a flag that mac80211 needs to keep a list of all frames send out to the driver and listens for ACK's. As soon as a ACK was passed from driver to mac80211 it could check if the corresponding frame was in the list and remove the frame from the list and generate a tx_status response indicating success. Off course all frames must be checked for the timeout value as well to see if the frame wasn't send (in which case the tx_status event is send as well). There shouldn't be a problem with multi-queue with this if the list of frames is put onto a single list instead of one list per queue. As for the retries and other statistics, do we honestly care? At the moment rt2500usb/rt73usb indicate the frame has not been acked and set the retry value to 1. If we somehow can tell if the frame was send out or not, isn't that a step forward already? The retry value is needed for the rate algorithm, but it is receiving the same incorrect value now as well, so it wouldn't be a step backward in that perspective. ;) Ivo -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
