On 2013-03-17 10:23 PM, Karl Beldan wrote: > On Fri, Mar 15, 2013 at 04:36:58PM +0100, Johannes Berg wrote: >> On Tue, 2013-03-12 at 10:41 +0100, Karl Beldan wrote: >> > On Wed, Feb 13, 2013 at 10:51:08AM +0100, Felix Fietkau wrote: >> > > When MCS rates start to get bad in 2.4 GHz because of long range or >> > > strong interference, CCK rates can be a lot more robust. >> > > >> > > This patch adds a pseudo MCS group containing CCK rates (long preamble >> > > in the lower 4 slots, short preamble in the upper slots). >> > > >> > With this, mac80211 might send CCK rates with IEEE80211_TX_CTL_AMPDU set. >> > For aggregates, if we don't currently set NO_CCK, at the very least the >> > 1st rate index should belong to an MCS_GROUP. >> >> I guess that depends on how you expect rate control to work ... I'd >> kinda expect the driver to skip aggregation then? I think only ath9k >> even uses minstrel + aggregation? >> > > This changes the meaning of IEEE80211_TX_CTL_AMPDU. > With this there are more possible RC feedback pitfalls with the tx statuses > IEEE80211_TX_{CTL,STAT}_AMPDU flags. > Regarding the drivers using minstrel + aggregation I can't really say, I > know ath9k runs ok with it and at work I settled for minstrel too with a > driver for our IP on a demo board. It's important that the IEEE80211_TX_CTL_AMPDU flag is still set, because the frame is still part of the BlockAck window, just sent with a rate that doesn't allow aggregating it with other frames, so it is still part of the A-MPDU session. If there are any drivers that cannot easily be changed to support that, we should have an explicit flag to disable using CCK with 802.11n stations. - Felix -- 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