[PATCH] [33/139] ath9k: fix bug in tx power

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Matteo Croce <technoboy85@xxxxxxxxx>

commit 841051602e3fa18ea468fe5a177aa92b6eb44b56 upstream.

The ath9k driver subtracts 3 dBm to the txpower as with two radios the
signal power is doubled.
The resulting value is assigned in an u16 which overflows and makes
the card work at full power.

Signed-off-by: Matteo Croce <matteo@xxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 drivers/net/wireless/ath/ath9k/eeprom_def.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Index: linux-2.6.35.y/drivers/net/wireless/ath/ath9k/eeprom_def.c
===================================================================
--- linux-2.6.35.y.orig/drivers/net/wireless/ath/ath9k/eeprom_def.c
+++ linux-2.6.35.y/drivers/net/wireless/ath/ath9k/eeprom_def.c
@@ -1064,15 +1064,19 @@ static void ath9k_hw_set_def_power_per_r
 	case 1:
 		break;
 	case 2:
-		scaledPower -= REDUCE_SCALED_POWER_BY_TWO_CHAIN;
+		if (scaledPower > REDUCE_SCALED_POWER_BY_TWO_CHAIN)
+			scaledPower -= REDUCE_SCALED_POWER_BY_TWO_CHAIN;
+		else
+			scaledPower = 0;
 		break;
 	case 3:
-		scaledPower -= REDUCE_SCALED_POWER_BY_THREE_CHAIN;
+		if (scaledPower > REDUCE_SCALED_POWER_BY_THREE_CHAIN)
+			scaledPower -= REDUCE_SCALED_POWER_BY_THREE_CHAIN;
+		else
+			scaledPower = 0;
 		break;
 	}
 
-	scaledPower = max((u16)0, scaledPower);
-
 	if (IS_CHAN_2GHZ(chan)) {
 		numCtlModes = ARRAY_SIZE(ctlModesFor11g) -
 			SUB_NUM_CTL_MODES_AT_2G_40;
--
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