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mac80211: VHT off-by-one NSS 

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 <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Karl Beldan 2013-04-15 17:09:29 +02:00 committed by Johannes Berg
parent fffa4b1c17
commit 6bc8312f95
1 changed files with 3 additions and 3 deletions
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6
include/net/mac80211.h
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@ -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;
}
/**