[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: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 0f824b2..360f03a 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -193,6 +193,133 @@
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 @@
* Update statistics.
*/
rt2x00dev->ops->lib->link_stats(rt2x00dev, &rt2x00dev->link.qual);
-
rt2x00dev->low_level_stats.dot11FCSErrorCount +=
rt2x00dev->link.qual.rx_failed;
@@ -273,6 +399,11 @@
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 @@
}
}
- 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