On Thu, Jan 22, 2009 at 5:15 PM, Kalle Valo <kalle.valo@xxxxxxxxx> wrote: > Currently mac80211 checks for the multicast tim bit from beacons, > disables power save and sends a null frame if the bit is set. This was > added to support ath9k. But this is a bit controversial because the AP will > send multicast frames immediately after the beacon and the time constraints > are really high. Relying mac80211 to be fast enough here might not be > reliable in all situations. I agree that mac80211 is not fast enough to disable power save when multicast bit is set. But a quick testing with multicast traffic with power save enabled shows me that the traffic is passing without much failures(97% passes through and this is not a small number considering my high traffic/noisy channel conditions). So, the reason is not strong enough or the mac80211 is not too slow to respond to a mc traffic in practical conditions and hence the check need not be removed. > And there's no need to send a null frame, AP > will send the frames immediately after the dtim beacon no matter what. You are right. In that case, if mc bit is set, we can change the code to just disable ps and not to send a null frame. But this pops up another issue! How to enable ps after waking up for mc traffic? For this we have got to have the dynamic_ps_timer called from the rx path also. This enables ps after the specified timeout. I don't see any good reason for not to have this timer in Rx path also. Thoughts? Thanks Vivek. -- 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
