Adjust positive RSSI only for some implementation.

Wifi chip can report positive rssi when STA and AP
are very close(close to zero distance apart). There are some
driver implementations where they avoid large negative rssi reporting
by adding with 256. Adjust the RSSI only for such implementations.

Bug: 146811944
Test: Placed STA and AP close to each other and confirmed that all signal bars
are shown indicating strong rssi.

Change-Id: Iab9af736782b2b61692bdf5795b54a28da28bfd0

1 files changed, 6 insertions, 4 deletions

diff --git a/service/java/com/android/server/wifi/ClientModeImpl.java b/service/java/com/android/server/wifi/ClientModeImpl.java
index 7da4b6fd1..08afc04bf 100644
--- a/service/java/com/android/server/wifi/ClientModeImpl.java
+++ b/service/java/com/android/server/wifi/ClientModeImpl.java
@@ -2277,11 +2277,13 @@ public class ClientModeImpl extends StateMachine {
         }
 
         if (newRssi > WifiInfo.INVALID_RSSI && newRssi < WifiInfo.MAX_RSSI) {
-            // screen out invalid values
-            /* some implementations avoid negative values by adding 256
-             * so we need to adjust for that here.
+            /*
+             * Positive RSSI is possible when devices are close(~0m apart) to each other.
+             * And there are some driver/firmware implementation, where they avoid
+             * reporting large negative rssi values by adding 256.
+             * so adjust the valid rssi reports for such implementations.
              */
-            if (newRssi > 0) {
+            if (newRssi > (WifiInfo.INVALID_RSSI + 256)) {
                 Log.wtf(TAG, "Error! +ve value RSSI: " + newRssi);
                 newRssi -= 256;
             }