power_control: do nothing if 'rx-current' equals 'rx-target'

It makes no sense to do further calculations if the actual Uplink
signal strength equals the target value configured in the VTY.

Change-Id: Id99c7013a722403e773df8367b1a9d7a856e639b
Related: SYS#4916

2 files changed, 16 insertions, 3 deletions

diff --git a/src/common/power_control.c b/src/common/power_control.c
index 4798f4fa..e2d1254a 100644
--- a/src/common/power_control.c
+++ b/src/common/power_control.c
@@ -143,6 +143,19 @@ int lchan_ms_pwr_ctrl(struct gsm_lchan *lchan,
 	   to reach expected power. */
 	diff = bts->ul_power_target - avg_ul_rssi_dbm;
 
+
+	/* TODO: introduce 'hysteresis' defining a range of tolerable deviation */
+	if (diff == 0) {
+		LOGPLCHAN(lchan, DLOOP, LOGL_INFO,
+			  "Keeping MS power at control level %d (%d dBm) because diff %d dBm "
+			  "from 'rx-target' %d dBm is not significant\n",
+			  ms_power_lvl, ms_dbm, diff, bts->ul_power_target);
+		/* Keep the current power level in sync (just to be sure) */
+		lchan->ms_power_ctrl.current = ms_power_lvl;
+		bts_model_adjst_ms_pwr(lchan);
+		return 0;
+	}
+
 	/* don't ever change more than MS_{LOWER,RAISE}_MAX_DBM during one loop
 	   iteration, i.e. reduce the speed at which the MS transmit power can
 	   change. A higher value means a lower level (and vice versa) */
diff --git a/tests/power/power_test.err b/tests/power/power_test.err
index 786f2a7b..1aac5e5c 100644
--- a/tests/power/power_test.err
+++ b/tests/power/power_test.err
@@ -4,7 +4,7 @@
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 11 (8 dBm) to 9, 12 dBm (rx-ms-pwr-lvl 11, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 9 (12 dBm) to 7, 16 dBm (rx-ms-pwr-lvl 9, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 7 (16 dBm) to 5, 20 dBm (rx-ms-pwr-lvl 7, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
-(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 5, 20 dBm (rx-ms-pwr-lvl 5, max-ms-pwr-lvl 2, rx-current -75 dBm, rx-target -75 dBm)
+(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 5 (20 dBm) because diff 0 dBm from 'rx-target' -75 dBm is not significant
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 5 (20 dBm) to 3, 24 dBm (rx-ms-pwr-lvl 5, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 3 (24 dBm) to 2, 26 dBm (rx-ms-pwr-lvl 3, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 2, 26 dBm (rx-ms-pwr-lvl 2, max-ms-pwr-lvl 2, rx-current -90 dBm, rx-target -75 dBm)
@@ -13,7 +13,7 @@
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 0 (30 dBm) to 30, 34 dBm (rx-ms-pwr-lvl 0, max-ms-pwr-lvl 29, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 30 (34 dBm) to 29, 36 dBm (rx-ms-pwr-lvl 30, max-ms-pwr-lvl 29, rx-current -90 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 29, 36 dBm (rx-ms-pwr-lvl 29, max-ms-pwr-lvl 29, rx-current -90 dBm, rx-target -75 dBm)
-(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 29, 36 dBm (rx-ms-pwr-lvl 29, max-ms-pwr-lvl 29, rx-current -75 dBm, rx-target -75 dBm)
+(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 29 (36 dBm) because diff 0 dBm from 'rx-target' -75 dBm is not significant
 (bts=0,trx=0,ts=0,ss=0) Lowering MS power from control level 29 (36 dBm) to 1, 28 dBm (rx-ms-pwr-lvl 29, max-ms-pwr-lvl 29, rx-current -45 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Lowering MS power from control level 1 (28 dBm) to 5, 20 dBm (rx-ms-pwr-lvl 1, max-ms-pwr-lvl 29, rx-current -45 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Lowering MS power from control level 5 (20 dBm) to 9, 12 dBm (rx-ms-pwr-lvl 5, max-ms-pwr-lvl 29, rx-current -45 dBm, rx-target -75 dBm)
@@ -21,7 +21,7 @@
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 10 (10 dBm) to 9, 12 dBm (rx-ms-pwr-lvl 10, max-ms-pwr-lvl 29, rx-current -77 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Lowering MS power from control level 9 (12 dBm) to 14, 2 dBm (rx-ms-pwr-lvl 9, max-ms-pwr-lvl 14, rx-current -73 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Lowering MS power from control level 14 (2 dBm) to 15, 0 dBm (rx-ms-pwr-lvl 14, max-ms-pwr-lvl 0, rx-current -40 dBm, rx-target -75 dBm)
-(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 15, 0 dBm (rx-ms-pwr-lvl 15, max-ms-pwr-lvl 2, rx-current -75 dBm, rx-target -75 dBm)
+(bts=0,trx=0,ts=0,ss=0) Keeping MS power at control level 15 (0 dBm) because diff 0 dBm from 'rx-target' -75 dBm is not significant
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 15 (0 dBm) to 13, 3 dBm (rx-ms-pwr-lvl 15, max-ms-pwr-lvl 2, rx-current -78 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 13 (4 dBm) to 11, 8 dBm (rx-ms-pwr-lvl 13, max-ms-pwr-lvl 2, rx-current -80 dBm, rx-target -75 dBm)
 (bts=0,trx=0,ts=0,ss=0) Raising MS power from control level 11 (8 dBm) to 9, 11 dBm (rx-ms-pwr-lvl 11, max-ms-pwr-lvl 2, rx-current -78 dBm, rx-target -75 dBm)