rt2x00: Fix rounding errors in RSSI average calculation

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@telia.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 704e94474b1..e6e73be31e3 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