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>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 2265445..61856e1 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -107,7 +107,8 @@
}
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 @@
*
* 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 @@
* 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 @@
{
struct ieee80211_sub_if_data *sdata;
u16 dur;
- int erp;
+ int erp, shift = 0;
bool short_preamble = false;
erp = 0;
@@ -177,10 +187,11 @@
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 @@
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 @@
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 @@
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 @@
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);