On Tue, Sep 14, 2010 at 9:39 AM, Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> wrote: > On Tue, Sep 14, 2010 at 8:00 AM, Luis R. Rodriguez > <lrodriguez@xxxxxxxxxxx> wrote: >> When we return to the home channel we were never reseting our beacon >> timers, this was casued by the fact that the scanning flag was still >> on even after we returned to our home channel. There are also other >> reasons why we would get a reset and if we are not off channel >> we always need to resynch our beacon timers, because a reset will >> clear them. >> >> For more details refer to: >> >> http://code.google.com/p/chromium-os/issues/detail?id=5715 >> >> This bug is a regression introduced on 2.6.36. The order of the >> changes are as follows: >> >> 5ee08656 - Sat Jul 31 - ath9k: prevent calibration during off-channel activity >> a0daa0e7 - Tue Jul 27 - Revert "mac80211: fix sw scan bracketing" >> 543708be - Fri Jun 18 - mac80211: fix sw scan bracketing >> >> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >> --contains 5ee0865615f65f84e6ee9174771a6716c29e08e1 >> v2.6.36-rc1~43^2~34^2~22 >> >> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >> --contains a0daa0e7592ada797d6835f11529097aabc27ad2 >> v2.6.36-rc1~571^2~64^2~13 >> >> mcgrof@tux ~/linux-2.6-allstable (git::master)$ git describe \ >> --contains 543708be320d7df692d24b349ca01a947b340764 >> v2.6.36-rc1~571^2~107^2~187 >> >> So 5ee08656 would have worked if a0daa0e7 was not committed but >> it was so this means 5ee08656 was broken since it assumed that >> when we were in the channel change routine the scan flag would >> be lifted. As it turns out the scan flag will be set when we >> are already on the home channel. >> >> These issues will need to be considered for our solution on >> reshifting the scan complete callback location on mac80211 on >> current development kernel work. >> >> This patch has stable fixes which apply down to [2.6.36+] >> >> Cc: stable@xxxxxxxxxx >> Cc: Paul Stewart <pstew@xxxxxxxxxx> >> Cc: Amod Bodas <amod.bodas@xxxxxxxxxxx> >> Signed-off-by: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> >> --- >> >> This v2 clarifies the second to last sentence, on the v1 this >> was just jiberish on my first read.. this should clarify what >> I meant. >> >> drivers/net/wireless/ath/ath9k/main.c | 6 ++++-- >> 1 files changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c >> index ba029b2..e349619 100644 >> --- a/drivers/net/wireless/ath/ath9k/main.c >> +++ b/drivers/net/wireless/ath/ath9k/main.c >> @@ -258,9 +258,11 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw, >> if (!(sc->sc_flags & (SC_OP_OFFCHANNEL | SC_OP_SCANNING))) { >> ath_start_ani(common); >> ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0); >> - ath_beacon_config(sc, NULL); >> } >> >> + if (!(sc->sc_flags & (SC_OP_OFFCHANNEL))) >> + ath_beacon_config(sc, NULL); >> + > > Upon further thought this change should just remove the SC_OP_SCANNING > flag from above and let the code there run when we are not off > channel. Reason is that as I noted above on the commit log entry the > scan flag will be set even when we return to the home channel due to > the races in mac80211 that were actually fixed by Johannes but later > reverted due to issues. Doing the fix this way would also let us > re-arm ANI and the tx completion monitor, this was also broken! I'll > respin this patch shortly after some basic testing. I should also note that this patch fixes the issue of reseting the beacon timers upon a reset, likely when the tx monitor hits -- I suspect that when that currently would hit we'd actually be out of synch with the AP and disconnect. This patch fixes that, but I just reviewed older kernels and the offchannel flag was not available prior to 2.6.36 so we can only fix this properly on >= 2.6.36 unless we figure out a way to annotate we're on the home channel. If we do we can potentially propagate a fix down to older kernels than 2.6.36 eventually. Luis -- 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
