Return-path: Received: from mail-we0-f170.google.com ([74.125.82.170]:60009 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751467Ab3DOPOK (ORCPT ); Mon, 15 Apr 2013 11:14:10 -0400 Received: by mail-we0-f170.google.com with SMTP id z2so3744370wey.15 for ; Mon, 15 Apr 2013 08:14:08 -0700 (PDT) From: Karl Beldan To: Johannes Berg Cc: linux-wireless , Karl Beldan , Karl Beldan Subject: [PATCH 1/2] mac80211: VHT off-by-one NSS Date: Mon, 15 Apr 2013 17:09:29 +0200 Message-Id: <1366038570-12457-1-git-send-email-karl.beldan@gmail.com> (sfid-20130415_171419_407874_4CB69D2B) Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Karl Beldan The number of VHT spatial streams (NSS) is found in: - s8 ieee80211_tx_rate.rate.idx[6:4] (tx - filled by rate control) - u8 ieee80211_rx_status.vht_nss (rx - filled by driver) Tx discriminates valid rates indexes with the sign bit and encodes NSS starting from 0 to 7 (note this matches some hw encodings e.g IWLMVM). Rx does not have the same constraints, and encodes NSS starting from 1 to 8 (note this matches what wireshark expects in the radiotap header). To handle ieee80211_tx_rate.rate.idx[6:4] ieee80211_rate_set_vht() and ieee80211_rate_get_vht_nss() assume their nss parameter and return value respectively runs from 0 to 7. ATM, there are only 2 users of these: cfg.c:sta_set_rate_info_t() and iwlwifi/mvm/tx.c:iwl_mvm_hwrate_to_tx_control(), but both assume nss runs from 1 to 8. This patch fixes this inconsistency by making ieee80211_rate_set_vht() and ieee80211_rate_get_vht_nss() handle an nss running from 1 to 8. Signed-off-by: Karl Beldan --- This might feel very verbose for such a trivial thing. include/net/mac80211.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 0dde213..2317ca9 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -601,8 +601,8 @@ static inline void ieee80211_rate_set_vht(struct ieee80211_tx_rate *rate, u8 mcs, u8 nss) { WARN_ON(mcs & ~0xF); - WARN_ON(nss & ~0x7); - rate->idx = (nss << 4) | mcs; + WARN_ON((nss - 1) & ~0x7); + rate->idx = ((nss - 1) << 4) | mcs; } static inline u8 @@ -614,7 +614,7 @@ ieee80211_rate_get_vht_mcs(const struct ieee80211_tx_rate *rate) static inline u8 ieee80211_rate_get_vht_nss(const struct ieee80211_tx_rate *rate) { - return rate->idx >> 4; + return (rate->idx >> 4) + 1; } /** -- 1.8.2