On 18/09/2012 15:46, Sujith Manoharan wrote: > Nicolas Cavallari wrote: >> With an AR9382 (well, i think, its PCI-id is 168c:0030 rev 1/168c:3116), >> each time I join an IBSS network, the driver repeatedly >> resets the queue for a while, because of too many missed beacons. After >> some time, this stops and the card behave normally. But many packets >> are lost in the process. >> >> The problem seems to aggravate when the number of IBSS nodes is higher : >> When joining a IBSS network with only one node, Only a few (e.g. 4) >> beacons are lost, and no reset takes places. When joining an IBSS >> network with two nodes, the queues can be reset up to 224 times in 20 >> seconds. When joining large IBSS networks, it sometimes never stop >> resetting. Occasionally, when resetting, the driver fails to reset TX DMA >> >> If i hack the driver to not reset when the beacon is stuck, the beacon >> tx resumes quickly by itself after 80-200 misses and the network seems >> to work normally (if not better). On large&clogged ad-hoc networks, the >> card sometimes miss between 1 and 80 beacons, but it might be due to >> background scanning i think. >> >> What could be the problem here ? is ad-hoc beaconing kind of broken ? >> I do not have the problem with AR9285. > > I think the problem is that we are programming the beacon timers based on > the beacon interval right after joining, but we base it on the HW TSF which > has just been reset. We should be updating the timers based on the TSF after a > HW sync has been done with a received beacon. This is being done for station > mode, but IBSS mode is missing this. > > Here is a very rough patch, it abuses STA-mode flags and doesn't differentiate > between creator/joiner mode, but can you check if it makes any difference ? With this patch, i see no beacon miss in the logs when joining a large ad-hoc network. So yes, it does make a difference! haven't tested what happens when creating an IBSS with or without this patch yet. Thanks. -- 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
