Commit 69f81a2c authored by Ivo van Doorn's avatar Ivo van Doorn Committed by David S. Miller
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[PATCH] rt2x00: Implement SW diversity



When mac80211 indicates that the default antenna setup
should be used _and_ that this default setup is SW_DIVERSITY.

This requires sampling and storing the RSSI per antenna
and check once every 2 seconds to determine if the RSSI
has changed significantly. Once this is the case we should sample
the other antenna for a short period and evaluate if
we need to swap antenna or not.
Signed-off-by: default avatarIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8de8c516
......@@ -240,6 +240,43 @@ struct link_qual {
#define WEIGHT_TX 40
};
/*
* Antenna settings about the currently active link.
*/
struct link_ant {
/*
* Antenna flags
*/
unsigned int flags;
#define ANTENNA_RX_DIVERSITY 0x00000001
#define ANTENNA_TX_DIVERSITY 0x00000002
#define ANTENNA_MODE_SAMPLE 0x00000004
/*
* Currently active TX/RX antenna setup.
* When software diversity is used, this will indicate
* which antenna is actually used at this time.
*/
struct antenna_setup active;
/*
* RSSI information for the different antenna's.
* These statistics are used to determine when
* to switch antenna when using software diversity.
*
* rssi[0] -> Antenna A RSSI
* rssi[1] -> Antenna B RSSI
*/
int rssi_history[2];
/*
* Current RSSI average of the currently active antenna.
* Similar to the avg_rssi in the link_qual structure
* this value is updated by using the walking average.
*/
int rssi_ant;
};
/*
* To optimize the quality of the link we need to store
* the quality of received frames and periodically
......@@ -259,11 +296,9 @@ struct link {
struct link_qual qual;
/*
* Currently active TX/RX antenna setup.
* When software diversity is used, this will indicate
* which antenna is actually used at this time.
* TX/RX antenna setup.
*/
struct antenna_setup active_ant;
struct link_ant ant;
/*
* Active VGC level
......@@ -277,25 +312,47 @@ struct link {
};
/*
* Update the rssi using the walking average approach.
* Small helper macro to work with moving/walking averages.
*/
static inline void rt2x00_update_link_rssi(struct link *link, int rssi)
{
if (link->qual.avg_rssi)
rssi = ((link->qual.avg_rssi * 7) + rssi) / 8;
link->qual.avg_rssi = rssi;
}
#define MOVING_AVERAGE(__avg, __val, __samples) \
( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )
/*
* When we lack RSSI information return something less then -80 to
* tell the driver to tune the device to maximum sensitivity.
*/
#define DEFAULT_RSSI ( -128 )
/*
* When the avg_rssi is unset or no frames have been received),
* we need to return the default value which needs to be less
* than -80 so the device will select the maximum sensitivity.
* Link quality access functions.
*/
static inline int rt2x00_get_link_rssi(struct link *link)
{
if (link->qual.avg_rssi && link->qual.rx_success)
return link->qual.avg_rssi;
return -128;
return DEFAULT_RSSI;
}
static inline int rt2x00_get_link_ant_rssi(struct link *link)
{
if (link->ant.rssi_ant && link->qual.rx_success)
return link->ant.rssi_ant;
return DEFAULT_RSSI;
}
static inline int rt2x00_get_link_ant_rssi_history(struct link *link,
enum antenna ant)
{
if (link->ant.rssi_history[ant - ANTENNA_A])
return link->ant.rssi_history[ant - ANTENNA_A];
return DEFAULT_RSSI;
}
static inline int rt2x00_update_ant_rssi(struct link *link, int rssi)
{
int old_rssi = link->ant.rssi_history[link->ant.active.rx - ANTENNA_A];
link->ant.rssi_history[link->ant.active.rx - ANTENNA_A] = rssi;
return old_rssi;
}
/*
......
......@@ -94,6 +94,26 @@ void rt2x00lib_config_type(struct rt2x00_dev *rt2x00dev, const int type)
rt2x00dev->ops->lib->config_type(rt2x00dev, type, tsf_sync);
}
void rt2x00lib_config_antenna(struct rt2x00_dev *rt2x00dev,
enum antenna rx, enum antenna tx)
{
struct rt2x00lib_conf libconf;
libconf.ant.rx = rx;
libconf.ant.tx = tx;
/*
* Write new antenna setup to device and reset the link tuner.
* The latter is required since we need to recalibrate the
* noise-sensitivity ratio for the new setup.
*/
rt2x00dev->ops->lib->config(rt2x00dev, CONFIG_UPDATE_ANTENNA, &libconf);
rt2x00lib_reset_link_tuner(rt2x00dev);
rt2x00dev->link.ant.active.rx = libconf.ant.rx;
rt2x00dev->link.ant.active.tx = libconf.ant.tx;
}
void rt2x00lib_config(struct rt2x00_dev *rt2x00dev,
struct ieee80211_conf *conf, const int force_config)
{
......@@ -101,7 +121,7 @@ void rt2x00lib_config(struct rt2x00_dev *rt2x00dev,
struct ieee80211_hw_mode *mode;
struct ieee80211_rate *rate;
struct antenna_setup *default_ant = &rt2x00dev->default_ant;
struct antenna_setup *active_ant = &rt2x00dev->link.active_ant;
struct antenna_setup *active_ant = &rt2x00dev->link.ant.active;
int flags = 0;
int short_slot_time;
......@@ -247,6 +267,6 @@ config:
rt2x00dev->rx_status.freq = conf->freq;
rt2x00dev->rx_status.channel = conf->channel;
rt2x00dev->tx_power = conf->power_level;
rt2x00dev->link.active_ant.rx = libconf.ant.rx;
rt2x00dev->link.active_ant.tx = libconf.ant.tx;
rt2x00dev->link.ant.active.rx = libconf.ant.rx;
rt2x00dev->link.ant.active.tx = libconf.ant.tx;
}
......@@ -193,6 +193,133 @@ void rt2x00lib_toggle_rx(struct rt2x00_dev *rt2x00dev, enum dev_state state)
rt2x00lib_start_link_tuner(rt2x00dev);
}
static void rt2x00lib_evaluate_antenna_sample(struct rt2x00_dev *rt2x00dev)
{
enum antenna rx = rt2x00dev->link.ant.active.rx;
enum antenna tx = rt2x00dev->link.ant.active.tx;
int sample_a =
rt2x00_get_link_ant_rssi_history(&rt2x00dev->link, ANTENNA_A);
int sample_b =
rt2x00_get_link_ant_rssi_history(&rt2x00dev->link, ANTENNA_B);
/*
* We are done sampling. Now we should evaluate the results.
*/
rt2x00dev->link.ant.flags &= ~ANTENNA_MODE_SAMPLE;
/*
* During the last period we have sampled the RSSI
* from both antenna's. It now is time to determine
* which antenna demonstrated the best performance.
* When we are already on the antenna with the best
* performance, then there really is nothing for us
* left to do.
*/
if (sample_a == sample_b)
return;
if (rt2x00dev->link.ant.flags & ANTENNA_RX_DIVERSITY) {
if (sample_a > sample_b && rx == ANTENNA_B)
rx = ANTENNA_A;
else if (rx == ANTENNA_A)
rx = ANTENNA_B;
}
if (rt2x00dev->link.ant.flags & ANTENNA_TX_DIVERSITY) {
if (sample_a > sample_b && tx == ANTENNA_B)
tx = ANTENNA_A;
else if (tx == ANTENNA_A)
tx = ANTENNA_B;
}
rt2x00lib_config_antenna(rt2x00dev, rx, tx);
}
static void rt2x00lib_evaluate_antenna_eval(struct rt2x00_dev *rt2x00dev)
{
enum antenna rx = rt2x00dev->link.ant.active.rx;
enum antenna tx = rt2x00dev->link.ant.active.tx;
int rssi_curr = rt2x00_get_link_ant_rssi(&rt2x00dev->link);
int rssi_old = rt2x00_update_ant_rssi(&rt2x00dev->link, rssi_curr);
/*
* Legacy driver indicates that we should swap antenna's
* when the difference in RSSI is greater that 5. This
* also should be done when the RSSI was actually better
* then the previous sample.
* When the difference exceeds the threshold we should
* sample the rssi from the other antenna to make a valid
* comparison between the 2 antennas.
*/
if ((rssi_curr - rssi_old) > -5 || (rssi_curr - rssi_old) < 5)
return;
rt2x00dev->link.ant.flags |= ANTENNA_MODE_SAMPLE;
if (rt2x00dev->link.ant.flags & ANTENNA_RX_DIVERSITY)
rx = (rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
if (rt2x00dev->link.ant.flags & ANTENNA_TX_DIVERSITY)
tx = (tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
rt2x00lib_config_antenna(rt2x00dev, rx, tx);
}
static void rt2x00lib_evaluate_antenna(struct rt2x00_dev *rt2x00dev)
{
/*
* Determine if software diversity is enabled for
* either the TX or RX antenna (or both).
* Always perform this check since within the link
* tuner interval the configuration might have changed.
*/
rt2x00dev->link.ant.flags &= ~ANTENNA_RX_DIVERSITY;
rt2x00dev->link.ant.flags &= ~ANTENNA_TX_DIVERSITY;
if (rt2x00dev->hw->conf.antenna_sel_rx == 0 &&
rt2x00dev->default_ant.rx != ANTENNA_SW_DIVERSITY)
rt2x00dev->link.ant.flags |= ANTENNA_RX_DIVERSITY;
if (rt2x00dev->hw->conf.antenna_sel_tx == 0 &&
rt2x00dev->default_ant.tx != ANTENNA_SW_DIVERSITY)
rt2x00dev->link.ant.flags |= ANTENNA_TX_DIVERSITY;
if (!(rt2x00dev->link.ant.flags & ANTENNA_RX_DIVERSITY) &&
!(rt2x00dev->link.ant.flags & ANTENNA_TX_DIVERSITY)) {
rt2x00dev->link.ant.flags &= ~ANTENNA_MODE_SAMPLE;
return;
}
/*
* If we have only sampled the data over the last period
* we should now harvest the data. Otherwise just evaluate
* the data. The latter should only be performed once
* every 2 seconds.
*/
if (rt2x00dev->link.ant.flags & ANTENNA_MODE_SAMPLE)
rt2x00lib_evaluate_antenna_sample(rt2x00dev);
else if (rt2x00dev->link.count & 1)
rt2x00lib_evaluate_antenna_eval(rt2x00dev);
}
static void rt2x00lib_update_link_stats(struct link *link, int rssi)
{
int avg_rssi = rssi;
/*
* Update global RSSI
*/
if (link->qual.avg_rssi)
avg_rssi = MOVING_AVERAGE(link->qual.avg_rssi, rssi, 8);
link->qual.avg_rssi = avg_rssi;
/*
* Update antenna RSSI
*/
if (link->ant.rssi_ant)
rssi = MOVING_AVERAGE(link->ant.rssi_ant, rssi, 8);
link->ant.rssi_ant = rssi;
}
static void rt2x00lib_precalculate_link_signal(struct link_qual *qual)
{
if (qual->rx_failed || qual->rx_success)
......@@ -261,7 +388,6 @@ static void rt2x00lib_link_tuner(struct work_struct *work)
* Update statistics.
*/
rt2x00dev->ops->lib->link_stats(rt2x00dev, &rt2x00dev->link.qual);
rt2x00dev->low_level_stats.dot11FCSErrorCount +=
rt2x00dev->link.qual.rx_failed;
......@@ -272,6 +398,11 @@ static void rt2x00lib_link_tuner(struct work_struct *work)
if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
rt2x00dev->ops->lib->link_tuner(rt2x00dev);
/*
* Evaluate antenna setup.
*/
rt2x00lib_evaluate_antenna(rt2x00dev);
/*
* Precalculate a portion of the link signal which is
* in based on the tx/rx success/failure counters.
......@@ -426,14 +557,15 @@ void rt2x00lib_rxdone(struct data_entry *entry, struct sk_buff *skb,
}
}
rt2x00_update_link_rssi(&rt2x00dev->link, desc->rssi);
rt2x00lib_update_link_stats(&rt2x00dev->link, desc->rssi);
rt2x00dev->link.qual.rx_success++;
rx_status->rate = val;
rx_status->signal =
rt2x00lib_calculate_link_signal(rt2x00dev, desc->rssi);
rx_status->ssi = desc->rssi;
rx_status->flag = desc->flags;
rx_status->antenna = rt2x00dev->link.active_ant.rx;
rx_status->antenna = rt2x00dev->link.ant.active.rx;
/*
* Send frame to mac80211
......
......@@ -53,6 +53,8 @@ void rt2x00lib_uninitialize(struct rt2x00_dev *rt2x00dev);
void rt2x00lib_config_mac_addr(struct rt2x00_dev *rt2x00dev, u8 *mac);
void rt2x00lib_config_bssid(struct rt2x00_dev *rt2x00dev, u8 *bssid);
void rt2x00lib_config_type(struct rt2x00_dev *rt2x00dev, const int type);
void rt2x00lib_config_antenna(struct rt2x00_dev *rt2x00dev,
enum antenna rx, enum antenna tx);
void rt2x00lib_config(struct rt2x00_dev *rt2x00dev,
struct ieee80211_conf *conf, const int force_config);
......
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