From: Avri Altman <[email protected]> There are a few APs our there that advertise U-APSD capabilities but don't implement it right which leads to poor traffic. These APs don't support MIMO or don't even support HT. Use this heuristic to detect them and disable U-APSD accordingly.
Signed-off-by: Avri Altman <[email protected]> Signed-off-by: Emmanuel Grumbach <[email protected]> --- net/mac80211/scan.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index 7bb6a93..3791c8a 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -39,6 +39,28 @@ void ieee80211_rx_bss_put(struct ieee80211_local *local, container_of((void *)bss, struct cfg80211_bss, priv)); } +/* + * An incompatible AP workaround: + * if the AP does not advertise MIMO capabilities disable U-APSD. + * iPhones, among others, advertise themselves as U-APSD capable when + * they aren't. Avoid connecting to those devices in U-APSD enabled. + */ +static bool broken_uapsd_workarounds(struct ieee802_11_elems *elems) +{ + int i; + + /* iPhone 4/4s with this problem doesn't have ht_capa */ + if (!elems->ht_cap_elem) + return true; + + for (i = 1; i < 4; i++) { + if (elems->ht_cap_elem->mcs.rx_mask[i]) + return false; + } + + return true; +} + static bool is_uapsd_supported(struct ieee802_11_elems *elems) { u8 qos_info; @@ -53,6 +75,9 @@ static bool is_uapsd_supported(struct ieee802_11_elems *elems) /* no valid wmm information or parameter element found */ return false; + if (broken_uapsd_workarounds(elems)) + return false; + return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD; } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
