From: Lars Ericsson <Lars_Ericsson@xxxxxxxxx>
Small changes in signal level was not detected up by the
MOVING_AVERAGE() due to a rounding error, using 'int' type.
rt2x00lib_antenna_diversity_eval:
rssi: -62 -62 -62 -62 -62 -62 -62 -62 -62 -62 -62 -62 -62 -62 -62
rssi_avg: -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57
The signal level reported back could be significantly (5dBm)
different from the actual value. A level +3dBm is the same as
double the AP output power.
Signed-off-by: Lars Ericsson <Lars_Ericsson@xxxxxxxxx>
Signed-off-by: Ivo van Doorn <IvDoorn@xxxxxxxxx>
---
drivers/net/wireless/rt2x00/rt2x00.h | 15 ++++++-
drivers/net/wireless/rt2x00/rt2x00link.c | 65 ++++++++++++++++++------------
2 files changed, 52 insertions(+), 28 deletions(-)
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index aa3ff0a..19ca146 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -134,6 +134,17 @@
GET_DURATION(IEEE80211_HEADER + ACK_SIZE, 10) )
/*
+ * Structure for average calculation
+ * The avg field contains the actual average value,
+ * but avg_weight is internally used during calculations
+ * to prevent rounding errors.
+ */
+struct avg_val {
+ int avg;
+ int avg_weight;
+};
+
+/*
* Chipset identification
* The chipset on the device is composed of a RT and RF chip.
* The chipset combination is important for determining device capabilities.
@@ -256,7 +267,7 @@ struct link_ant {
* Similar to the avg_rssi in the link_qual structure
* this value is updated by using the walking average.
*/
- int rssi_ant;
+ struct avg_val rssi_ant;
};
/*
@@ -285,7 +296,7 @@ struct link {
/*
* Currently active average RSSI value
*/
- int avg_rssi;
+ struct avg_val avg_rssi;
/*
* Currently precalculated percentages of successful
diff --git a/drivers/net/wireless/rt2x00/rt2x00link.c b/drivers/net/wireless/rt2x00/rt2x00link.c
index dd68f3a..c64db0b 100644
--- a/drivers/net/wireless/rt2x00/rt2x00link.c
+++ b/drivers/net/wireless/rt2x00/rt2x00link.c
@@ -46,7 +46,15 @@
#define DEFAULT_PERCENTAGE 50
/*
- * Small helper macro to work with moving/walking averages.
+ * Small helper macro for percentage calculation
+ * This is a very simple macro with the only catch that it will
+ * produce a default value in case no total value was provided.
+ */
+#define PERCENTAGE(__value, __total) \
+ ( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )
+
+/*
+ * Helper struct and macro to work with moving/walking averages.
* When adding a value to the average value the following calculation
* is needed:
*
@@ -60,18 +68,28 @@
* for a few minutes but when the device is moved away from the AP
* the average will not decrease fast enough to compensate.
* The walking average compensates this and will move towards
- * the new values correctly allowing a effective link tuning.
+ * the new values correctly allowing a effective link tuning,
+ * the speed of the average moving towards other values depends
+ * on the value for the number of samples. The higher the number
+ * of samples, the slower the average will move.
+ * We use two variables to keep track of the average value to
+ * compensate for the rounding errors. This can be a significant
+ * error (>5dBm) if the factor is too low.
*/
-#define MOVING_AVERAGE(__avg, __val, __samples) \
- ( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )
-
-/*
- * Small helper macro for percentage calculation
- * This is a very simple macro with the only catch that it will
- * produce a default value in case no total value was provided.
- */
-#define PERCENTAGE(__value, __total) \
- ( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )
+#define AVG_SAMPLES 8
+#define AVG_FACTOR 1000
+#define MOVING_AVERAGE(__avg, __val) \
+({ \
+ struct avg_val __new; \
+ __new.avg_weight = \
+ (__avg).avg_weight ? \
+ ((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
+ ((__val) * (AVG_FACTOR))) / \
+ (AVG_SAMPLES) ) : \
+ ((__val) * (AVG_FACTOR)); \
+ __new.avg = __new.avg_weight / (AVG_FACTOR); \
+ __new; \
+})
/*
* For calculating the Signal quality we have determined
@@ -98,8 +116,8 @@ static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
{
struct link_ant *ant = &rt2x00dev->link.ant;
- if (ant->rssi_ant && rt2x00dev->link.qual.rx_success)
- return ant->rssi_ant;
+ if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
+ return ant->rssi_ant.avg;
return DEFAULT_RSSI;
}
@@ -121,7 +139,8 @@ static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
{
- rt2x00dev->link.ant.rssi_ant = 0;
+ rt2x00dev->link.ant.rssi_ant.avg = 0;
+ rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
}
static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
@@ -258,8 +277,6 @@ void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
struct link_qual *qual = &rt2x00dev->link.qual;
struct link_ant *ant = &rt2x00dev->link.ant;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
- int avg_rssi = rxdesc->rssi;
- int ant_rssi = rxdesc->rssi;
/*
* Frame was received successfully since non-succesfull
@@ -279,16 +296,12 @@ void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
/*
* Update global RSSI
*/
- if (link->avg_rssi)
- avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
- link->avg_rssi = avg_rssi;
+ link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);
/*
* Update antenna RSSI
*/
- if (ant->rssi_ant)
- ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
- ant->rssi_ant = ant_rssi;
+ ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
}
static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
@@ -421,10 +434,10 @@ static void rt2x00link_tuner(struct work_struct *work)
* collect the RSSI data we could use this. Otherwise we
* must fallback to the default RSSI value.
*/
- if (!link->avg_rssi || !qual->rx_success)
+ if (!link->avg_rssi.avg || !qual->rx_success)
qual->rssi = DEFAULT_RSSI;
else
- qual->rssi = link->avg_rssi;
+ qual->rssi = link->avg_rssi.avg;
/*
* Only perform the link tuning when Link tuning
@@ -442,7 +455,7 @@ static void rt2x00link_tuner(struct work_struct *work)
/*
* Send a signal to the led to update the led signal strength.
*/
- rt2x00leds_led_quality(rt2x00dev, link->avg_rssi);
+ rt2x00leds_led_quality(rt2x00dev, qual->rssi);
/*
* Evaluate antenna setup, make this the last step when
--
1.6.3.3
--
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