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Commit 3a40414f authored by Johannes Berg's avatar Johannes Berg
Browse files

mac80211: connect with HT20 if HT40 is not permitted 



Some changes to fix issues with HT40 APs in Korea
and follow-up changes to allow using HT40 even if
the local regulatory database disallows it caused
issues with iwlwifi (and could cause issues with
other devices); iwlwifi firmware would assert if
you tried to connect to an AP that has an invalid
configuration (e.g. using HT40- on channel 140.)

Fix this, while avoiding the "Korean AP" issue by
disabling HT40 and advertising HT20 to the AP
when connecting.

Cc: stable@vger.kernel.org [3.6]
Reported-by: default avatarFlorian Reitmeir <florian@reitmeir.org>
Tested-by: default avatarFlorian Reitmeir <florian@reitmeir.org>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 6863255b

net/mac80211/mlme.c

+20 −10
Original line number Diff line number Diff line
@@ -3099,24 +3099,34 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata, 
				   ht_cfreq, ht_oper->primary_chan,

				   cbss->channel->band);

			ht_oper = NULL;

		} else {

			channel_type = NL80211_CHAN_HT20;

		}

	}



	if (ht_oper) {

		channel_type = NL80211_CHAN_HT20;

	if (ht_oper && sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {

		/*

		 * cfg80211 already verified that the channel itself can

		 * be used, but it didn't check that we can do the right

		 * HT type, so do that here as well. If HT40 isn't allowed

		 * on this channel, disable 40 MHz operation.

		 */



		if (sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {

			switch (ht_oper->ht_param &

					IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {

		switch (ht_oper->ht_param & IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {

		case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:

			if (cbss->channel->flags & IEEE80211_CHAN_NO_HT40PLUS)

				ifmgd->flags |= IEEE80211_STA_DISABLE_40MHZ;

			else

				channel_type = NL80211_CHAN_HT40PLUS;

			break;

		case IEEE80211_HT_PARAM_CHA_SEC_BELOW:

			if (cbss->channel->flags & IEEE80211_CHAN_NO_HT40MINUS)

				ifmgd->flags |= IEEE80211_STA_DISABLE_40MHZ;

			else

				channel_type = NL80211_CHAN_HT40MINUS;

			break;

		}

	}

	}



	if (!ieee80211_set_channel_type(local, sdata, channel_type)) {

		/* can only fail due to HT40+/- mismatch */