[PATCH v2 7/7] rt2x00: Fix HT40 operation in rt2800.

[Gertjan van Wingerde <gwingerde@gmail.com>]

Closer inspection of the legacy Ralink driver reveals that in case of HT40+
or HT40- we must adjust the frequency settings that we program to the device.
Implement the same adjustment in the rt2x00 code.

With this HT40 seems to work for all devices supported by rt2800pci and
rt2800usb.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
---

v2: Handled feedback from Ivo.

---
 drivers/net/wireless/rt2x00/rt2800lib.c    |    5 +----
 drivers/net/wireless/rt2x00/rt2x00config.c |   12 ++++++++----
 drivers/net/wireless/rt2x00/rt2x00ht.c     |   27 +++++++++++++++++++++++++++
 drivers/net/wireless/rt2x00/rt2x00lib.h    |    9 +++++++++
 4 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c
index 8ffbc3c..15322f0 100644
--- a/drivers/net/wireless/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/rt2x00/rt2800lib.c
@@ -2530,11 +2530,8 @@ int rt2800_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	else
 		spec->ht.ht_supported = false;
 
-	/*
-	 * Don't set IEEE80211_HT_CAP_SUP_WIDTH_20_40 for now as it causes
-	 * reception problems with HT40 capable 11n APs
-	 */
 	spec->ht.cap =
+	    IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
 	    IEEE80211_HT_CAP_GRN_FLD |
 	    IEEE80211_HT_CAP_SGI_20 |
 	    IEEE80211_HT_CAP_SGI_40 |
diff --git a/drivers/net/wireless/rt2x00/rt2x00config.c b/drivers/net/wireless/rt2x00/rt2x00config.c
index 098315a..8dbd634 100644
--- a/drivers/net/wireless/rt2x00/rt2x00config.c
+++ b/drivers/net/wireless/rt2x00/rt2x00config.c
@@ -170,23 +170,27 @@ void rt2x00lib_config(struct rt2x00_dev *rt2x00dev,
 		      unsigned int ieee80211_flags)
 {
 	struct rt2x00lib_conf libconf;
+	u16 hw_value;
 
 	memset(&libconf, 0, sizeof(libconf));
 
 	libconf.conf = conf;
 
 	if (ieee80211_flags & IEEE80211_CONF_CHANGE_CHANNEL) {
-		if (conf_is_ht40(conf))
+		if (conf_is_ht40(conf)) {
 			__set_bit(CONFIG_CHANNEL_HT40, &rt2x00dev->flags);
-		else
+			hw_value = rt2x00ht_center_channel(rt2x00dev, conf);
+		} else {
 			__clear_bit(CONFIG_CHANNEL_HT40, &rt2x00dev->flags);
+			hw_value = conf->channel->hw_value;
+		}
 
 		memcpy(&libconf.rf,
-		       &rt2x00dev->spec.channels[conf->channel->hw_value],
+		       &rt2x00dev->spec.channels[hw_value],
 		       sizeof(libconf.rf));
 
 		memcpy(&libconf.channel,
-		       &rt2x00dev->spec.channels_info[conf->channel->hw_value],
+		       &rt2x00dev->spec.channels_info[hw_value],
 		       sizeof(libconf.channel));
 	}
 
diff --git a/drivers/net/wireless/rt2x00/rt2x00ht.c b/drivers/net/wireless/rt2x00/rt2x00ht.c
index 5a40760..588c766 100644
--- a/drivers/net/wireless/rt2x00/rt2x00ht.c
+++ b/drivers/net/wireless/rt2x00/rt2x00ht.c
@@ -84,3 +84,31 @@ void rt2x00ht_create_tx_descriptor(struct queue_entry *entry,
 	else
 		txdesc->txop = TXOP_HTTXOP;
 }
+
+u16 rt2x00ht_center_channel(struct rt2x00_dev *rt2x00dev,
+			    struct ieee80211_conf *conf)
+{
+	struct hw_mode_spec *spec = &rt2x00dev->spec;
+	int center_channel;
+	u16 i;
+
+	/*
+	 * Initialize center channel to current channel.
+	 */
+	center_channel = spec->channels[conf->channel->hw_value].channel;
+
+	/*
+	 * Adjust center channel to HT40+ and HT40- operation.
+	 */
+	if (conf_is_ht40_plus(conf))
+		center_channel += 2;
+	else if (conf_is_ht40_minus(conf))
+		center_channel -= (center_channel == 14) ? 1 : 2;
+
+	for (i = 0; i < spec->num_channels; i++)
+		if (spec->channels[i].channel == center_channel)
+			return i;
+
+	WARN_ON(1);
+	return conf->channel->hw_value;
+}
diff --git a/drivers/net/wireless/rt2x00/rt2x00lib.h b/drivers/net/wireless/rt2x00/rt2x00lib.h
index 822affc..ed27de1 100644
--- a/drivers/net/wireless/rt2x00/rt2x00lib.h
+++ b/drivers/net/wireless/rt2x00/rt2x00lib.h
@@ -367,12 +367,21 @@ static inline void rt2x00crypto_rx_insert_iv(struct sk_buff *skb,
 void rt2x00ht_create_tx_descriptor(struct queue_entry *entry,
 				   struct txentry_desc *txdesc,
 				   const struct rt2x00_rate *hwrate);
+
+u16 rt2x00ht_center_channel(struct rt2x00_dev *rt2x00dev,
+			    struct ieee80211_conf *conf);
 #else
 static inline void rt2x00ht_create_tx_descriptor(struct queue_entry *entry,
 						 struct txentry_desc *txdesc,
 						 const struct rt2x00_rate *hwrate)
 {
 }
+
+static inline u16 rt2x00ht_center_channel(struct rt2x00_dev *rt2x00dev,
+					  struct ieee80211_conf *conf)
+{
+	return conf->channel->hw_value;
+}
 #endif /* CONFIG_RT2X00_LIB_HT */
 
 /*
-- 
1.7.1