p54: honour bss_info_changed's short slot time settings

This patch was made on behalf of Johannes request.
"mac80211 and IEEE80211_CONF_SHORT_SLOT_TIME"

Of course, bss_info_changed provides some more useful data.
e.g.: basic_rates, dtim_period, beacon_int and maybe even more.
Everything can be hooked up if it's necessary.
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54.h

@@ -81,6 +81,7 @@ struct p54_common {
 	unsigned int output_limit_len;
 	struct pda_pa_curve_data *curve_data;
 	unsigned int filter_flags;
+	bool use_short_slot;
 	u16 rxhw;
 	u8 version;
 	u8 rx_antenna;

drivers/net/wireless/p54/p54common.c

@@ -901,12 +901,10 @@ static int p54_set_filter(struct ieee80211_hw *dev, u16 filter_type,
 		memset(filter->bssid, ~0, ETH_ALEN);
 	else
 		memcpy(filter->bssid, bssid, ETH_ALEN);
-
 	filter->rx_antenna = priv->rx_antenna;
-
 	if (priv->fw_var < 0x500) {
 		data_len = P54_TX_CONTROL_FILTER_V1_LEN;
-		filter->v1.basic_rate_mask = cpu_to_le32(0x15F);
+		filter->v1.basic_rate_mask = cpu_to_le32(0x15f);
 		filter->v1.rx_addr = cpu_to_le32(priv->rx_end);
 		filter->v1.max_rx = cpu_to_le16(priv->rx_mtu);
 		filter->v1.rxhw = cpu_to_le16(priv->rxhw);
@@ -918,7 +916,6 @@ static int p54_set_filter(struct ieee80211_hw *dev, u16 filter_type,
 		filter->v2.rxhw = cpu_to_le16(priv->rxhw);
 		filter->v2.timer = cpu_to_le16(1000);
 	}
-
 	hdr->len = cpu_to_le16(data_len);
 	p54_assign_address(dev, NULL, hdr, sizeof(*hdr) + data_len);
 	priv->tx(dev, hdr, sizeof(*hdr) + data_len, 1);
@@ -1088,7 +1085,7 @@ static void p54_set_vdcf(struct ieee80211_hw *dev)
 
 	vdcf = (struct p54_tx_control_vdcf *) hdr->data;
 
-	if (dev->conf.flags & IEEE80211_CONF_SHORT_SLOT_TIME) {
+	if (priv->use_short_slot) {
 		vdcf->slottime = 9;
 		vdcf->magic1 = 0x10;
 		vdcf->magic2 = 0x00;
@@ -1135,7 +1132,6 @@ static int p54_start(struct ieee80211_hw *dev)
 		priv->mode = NL80211_IFTYPE_MONITOR;
 
 	p54_init_vdcf(dev);
-
 	mod_timer(&priv->stats_timer, jiffies + HZ);
 	return err;
 }
@@ -1351,6 +1347,19 @@ static int p54_get_tx_stats(struct ieee80211_hw *dev,
 	return 0;
 }
 
+static void p54_bss_info_changed(struct ieee80211_hw *dev,
+				 struct ieee80211_vif *vif,
+				 struct ieee80211_bss_conf *info,
+				 u32 changed)
+{
+	struct p54_common *priv = dev->priv;
+
+	if (changed & BSS_CHANGED_ERP_SLOT) {
+		priv->use_short_slot = info->use_short_slot;
+		p54_set_vdcf(dev);
+	}
+}
+
 static const struct ieee80211_ops p54_ops = {
 	.tx			= p54_tx,
 	.start			= p54_start,
@@ -1359,6 +1368,7 @@ static const struct ieee80211_ops p54_ops = {
 	.remove_interface	= p54_remove_interface,
 	.config			= p54_config,
 	.config_interface	= p54_config_interface,
+	.bss_info_changed	= p54_bss_info_changed,
 	.configure_filter	= p54_configure_filter,
 	.conf_tx		= p54_conf_tx,
 	.get_stats		= p54_get_stats,
@@ -1385,7 +1395,6 @@ struct ieee80211_hw *p54_init_common(size_t priv_data_len)
 	dev->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION);
 
 	dev->channel_change_time = 1000;	/* TODO: find actual value */
-
 	priv->tx_stats[0].limit = 1;
 	priv->tx_stats[1].limit = 1;
 	priv->tx_stats[2].limit = 1;