mac80211: fix timing for 5 MHz and 10 MHz channels

according to IEEE 802.11-2012 section 18, various timings change
when using 5 MHz and 10 MHz. Reflect this by using a "shift" when
calculating durations.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

5 files changed, 90 insertions, 25 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 683751a1eceb..338e7ca21ea5 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -812,6 +812,34 @@ ieee80211_get_sdata_band(struct ieee80211_sub_if_data *sdata)
         return band;
 }
 
+static inline int
+ieee80211_chandef_get_shift(struct cfg80211_chan_def *chandef)
+{
+        switch (chandef->width) {
+        case NL80211_CHAN_WIDTH_5:
+                return 2;
+        case NL80211_CHAN_WIDTH_10:
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+static inline int
+ieee80211_vif_get_shift(struct ieee80211_vif *vif)
+{
+        struct ieee80211_chanctx_conf *chanctx_conf;
+        int shift = 0;
+
+        rcu_read_lock();
+        chanctx_conf = rcu_dereference(vif->chanctx_conf);
+        if (chanctx_conf)
+                shift = ieee80211_chandef_get_shift(&chanctx_conf->def);
+        rcu_read_unlock();
+
+        return shift;
+}
+
 enum sdata_queue_type {
         IEEE80211_SDATA_QUEUE_TYPE_FRAME        = 0,
         IEEE80211_SDATA_QUEUE_AGG_START         = 1,
@@ -1468,7 +1496,8 @@ extern void *mac80211_wiphy_privid; /* for wiphy privid */
 u8 *ieee80211_get_bssid(struct ieee80211_hdr *hdr, size_t len,
                         enum nl80211_iftype type);
 int ieee80211_frame_duration(enum ieee80211_band band, size_t len,
-                             int rate, int erp, int short_preamble);
+                             int rate, int erp, int short_preamble,
+                             int shift);
 void mac80211_ev_michael_mic_failure(struct ieee80211_sub_if_data *sdata, int keyidx,
                                      struct ieee80211_hdr *hdr, const u8 *tsc,
                                      gfp_t gfp);
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index 5b25966add10..a507376d5316 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -382,14 +382,18 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 static void
 calc_rate_durations(enum ieee80211_band band,
                     struct minstrel_rate *d,
-                    struct ieee80211_rate *rate)
+                    struct ieee80211_rate *rate,
+                    struct cfg80211_chan_def *chandef)
 {
         int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
+        int shift = ieee80211_chandef_get_shift(chandef);
 
         d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
-                        rate->bitrate, erp, 1);
+                        DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
+                        shift);
         d->ack_time = ieee80211_frame_duration(band, 10,
-                        rate->bitrate, erp, 1);
+                        DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
+                        shift);
 }
 
 static void
@@ -425,14 +429,17 @@ minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
         struct ieee80211_rate *ctl_rate;
         unsigned int i, n = 0;
         unsigned int t_slot = 9; /* FIXME: get real slot time */
+        u32 rate_flags;
 
         mi->sta = sta;
         mi->lowest_rix = rate_lowest_index(sband, sta);
         ctl_rate = &sband->bitrates[mi->lowest_rix];
         mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
                                 ctl_rate->bitrate,
-                                !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1);
+                                !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
+                                ieee80211_chandef_get_shift(chandef));
 
+        rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
         memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
         mi->max_prob_rate = 0;
 
@@ -441,15 +448,22 @@ minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
                 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
                 unsigned int tx_time_single;
                 unsigned int cw = mp->cw_min;
+                int shift;
 
                 if (!rate_supported(sta, sband->band, i))
                         continue;
+                if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
+                        continue;
+
                 n++;
                 memset(mr, 0, sizeof(*mr));
 
                 mr->rix = i;
-                mr->bitrate = sband->bitrates[i].bitrate / 5;
-                calc_rate_durations(sband->band, mr, &sband->bitrates[i]);
+                shift = ieee80211_chandef_get_shift(chandef);
+                mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
+                                           (1 << shift) * 5);
+                calc_rate_durations(sband->band, mr, &sband->bitrates[i],
+                                    chandef);
 
                 /* calculate maximum number of retransmissions before
                  * fallback (based on maximum segment size) */
@@ -547,6 +561,7 @@ minstrel_init_cck_rates(struct minstrel_priv *mp)
 {
         static const int bitrates[4] = { 10, 20, 55, 110 };
         struct ieee80211_supported_band *sband;
+        u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
         int i, j;
 
         sband = mp->hw->wiphy->bands[IEEE80211_BAND_2GHZ];
@@ -559,6 +574,9 @@ minstrel_init_cck_rates(struct minstrel_priv *mp)
                 if (rate->flags & IEEE80211_RATE_ERP_G)
                         continue;
 
+                if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
+                        continue;
+
                 for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
                         if (rate->bitrate != bitrates[j])
                                 continue;
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 52562973fbd1..7475a7a33797 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -862,8 +862,9 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
         mi->sta = sta;
         mi->stats_update = jiffies;
 
-        ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
-        mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
+        ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
+        mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
+        mi->overhead += ack_dur;
         mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
 
         mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 4105d0ca963e..3523daa0b15c 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -40,7 +40,7 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                                  struct sk_buff *skb, int group_addr,
                                  int next_frag_len)
 {
-        int rate, mrate, erp, dur, i;
+        int rate, mrate, erp, dur, i, shift;
         struct ieee80211_rate *txrate;
         struct ieee80211_local *local = tx->local;
         struct ieee80211_supported_band *sband;
@@ -153,6 +153,8 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                 rate = mrate;
         }
 
+        shift = ieee80211_vif_get_shift(&tx->sdata->vif);
+
         /* Don't calculate ACKs for QoS Frames with NoAck Policy set */
         if (ieee80211_is_data_qos(hdr->frame_control) &&
             *(ieee80211_get_qos_ctl(hdr)) & IEEE80211_QOS_CTL_ACK_POLICY_NOACK)
@@ -162,7 +164,8 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                  * (10 bytes + 4-byte FCS = 112 bits) plus SIFS; rounded up
                  * to closest integer */
                 dur = ieee80211_frame_duration(sband->band, 10, rate, erp,
-                                tx->sdata->vif.bss_conf.use_short_preamble);
+                                tx->sdata->vif.bss_conf.use_short_preamble,
+                                shift);
 
         if (next_frag_len) {
                 /* Frame is fragmented: duration increases with time needed to
@@ -171,7 +174,8 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                 /* next fragment */
                 dur += ieee80211_frame_duration(sband->band, next_frag_len,
                                 txrate->bitrate, erp,
-                                tx->sdata->vif.bss_conf.use_short_preamble);
+                                tx->sdata->vif.bss_conf.use_short_preamble,
+                                shift);
         }
 
         return cpu_to_le16(dur);
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 22654452a561..61856e17a1e4 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -107,7 +107,8 @@ void ieee80211_tx_set_protected(struct ieee80211_tx_data *tx)
 }
 
 int ieee80211_frame_duration(enum ieee80211_band band, size_t len,
-                             int rate, int erp, int short_preamble)
+                             int rate, int erp, int short_preamble,
+                             int shift)
 {
         int dur;
 
@@ -118,6 +119,9 @@ int ieee80211_frame_duration(enum ieee80211_band band, size_t len,
          *
          * rate is in 100 kbps, so divident is multiplied by 10 in the
          * DIV_ROUND_UP() operations.
+         *
+         * shift may be 2 for 5 MHz channels or 1 for 10 MHz channels, and
+         * is assumed to be 0 otherwise.
          */
 
         if (band == IEEE80211_BAND_5GHZ || erp) {
@@ -130,15 +134,21 @@ int ieee80211_frame_duration(enum ieee80211_band band, size_t len,
                  * TXTIME = T_PREAMBLE + T_SIGNAL + T_SYM x N_SYM + Signal Ext
                  *
                  * T_SYM = 4 usec
-                 * 802.11a - 17.5.2: aSIFSTime = 16 usec
+                 * 802.11a - 18.5.2: aSIFSTime = 16 usec
                  * 802.11g - 19.8.4: aSIFSTime = 10 usec +
                  *      signal ext = 6 usec
                  */
                 dur = 16; /* SIFS + signal ext */
-                dur += 16; /* 17.3.2.3: T_PREAMBLE = 16 usec */
-                dur += 4; /* 17.3.2.3: T_SIGNAL = 4 usec */
+                dur += 16; /* IEEE 802.11-2012 18.3.2.4: T_PREAMBLE = 16 usec */
+                dur += 4; /* IEEE 802.11-2012 18.3.2.4: T_SIGNAL = 4 usec */
                 dur += 4 * DIV_ROUND_UP((16 + 8 * (len + 4) + 6) * 10,
                                         4 * rate); /* T_SYM x N_SYM */
+
+                /* IEEE 802.11-2012 18.3.2.4: all values above are:
+                 *  * times 4 for 5 MHz
+                 *  * times 2 for 10 MHz
+                 */
+                dur *= 1 << shift;
         } else {
                 /*
                  * 802.11b or 802.11g with 802.11b compatibility:
@@ -168,7 +178,7 @@ __le16 ieee80211_generic_frame_duration(struct ieee80211_hw *hw,
 {
         struct ieee80211_sub_if_data *sdata;
         u16 dur;
-        int erp;
+        int erp, shift = 0;
         bool short_preamble = false;
 
         erp = 0;
@@ -177,10 +187,11 @@ __le16 ieee80211_generic_frame_duration(struct ieee80211_hw *hw,
                 short_preamble = sdata->vif.bss_conf.use_short_preamble;
                 if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
                         erp = rate->flags & IEEE80211_RATE_ERP_G;
+                shift = ieee80211_vif_get_shift(vif);
         }
 
         dur = ieee80211_frame_duration(band, frame_len, rate->bitrate, erp,
-                                       short_preamble);
+                                       short_preamble, shift);
 
         return cpu_to_le16(dur);
 }
@@ -194,7 +205,7 @@ __le16 ieee80211_rts_duration(struct ieee80211_hw *hw,
         struct ieee80211_rate *rate;
         struct ieee80211_sub_if_data *sdata;
         bool short_preamble;
-        int erp;
+        int erp, shift = 0;
         u16 dur;
         struct ieee80211_supported_band *sband;
 
@@ -210,17 +221,18 @@ __le16 ieee80211_rts_duration(struct ieee80211_hw *hw,
                 short_preamble = sdata->vif.bss_conf.use_short_preamble;
                 if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
                         erp = rate->flags & IEEE80211_RATE_ERP_G;
+                shift = ieee80211_vif_get_shift(vif);
         }
 
         /* CTS duration */
         dur = ieee80211_frame_duration(sband->band, 10, rate->bitrate,
-                                       erp, short_preamble);
+                                       erp, short_preamble, shift);
         /* Data frame duration */
         dur += ieee80211_frame_duration(sband->band, frame_len, rate->bitrate,
-                                        erp, short_preamble);
+                                        erp, short_preamble, shift);
         /* ACK duration */
         dur += ieee80211_frame_duration(sband->band, 10, rate->bitrate,
-                                        erp, short_preamble);
+                                        erp, short_preamble, shift);
 
         return cpu_to_le16(dur);
 }
@@ -235,7 +247,7 @@ __le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw,
         struct ieee80211_rate *rate;
         struct ieee80211_sub_if_data *sdata;
         bool short_preamble;
-        int erp;
+        int erp, shift = 0;
         u16 dur;
         struct ieee80211_supported_band *sband;
 
@@ -250,15 +262,16 @@ __le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw,
                 short_preamble = sdata->vif.bss_conf.use_short_preamble;
                 if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
                         erp = rate->flags & IEEE80211_RATE_ERP_G;
+                shift = ieee80211_vif_get_shift(vif);
         }
 
         /* Data frame duration */
         dur = ieee80211_frame_duration(sband->band, frame_len, rate->bitrate,
-                                       erp, short_preamble);
+                                       erp, short_preamble, shift);
         if (!(frame_txctl->flags & IEEE80211_TX_CTL_NO_ACK)) {
                 /* ACK duration */
                 dur += ieee80211_frame_duration(sband->band, 10, rate->bitrate,
-                                                erp, short_preamble);
+                                                erp, short_preamble, shift);
         }
 
         return cpu_to_le16(dur);