ath5k: fix interpolation with equal power levels

When the EEPROM contains weird values for the power levels we have to
fix the interpolation process.
Signed-off-by: NFabio Rossi <rossi.f@inwind.it>
Acked-by: NNick Kossifidis <mickflemm@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath5k/phy.c

@@ -1487,28 +1487,35 @@ ath5k_get_linear_pcdac_min(const u8 *stepL, const u8 *stepR,
 {
 	s8 tmp;
 	s16 min_pwrL, min_pwrR;
-	s16 pwr_i = pwrL[0];
-
-	do {
-		pwr_i--;
-		tmp = (s8) ath5k_get_interpolated_value(pwr_i,
-						pwrL[0], pwrL[1],
-						stepL[0], stepL[1]);
-
-	} while (tmp > 1);
-
-	min_pwrL = pwr_i;
-
-	pwr_i = pwrR[0];
-	do {
-		pwr_i--;
-		tmp = (s8) ath5k_get_interpolated_value(pwr_i,
-						pwrR[0], pwrR[1],
-						stepR[0], stepR[1]);
-
-	} while (tmp > 1);
+	s16 pwr_i;
+
+	if (pwrL[0] == pwrL[1])
+		min_pwrL = pwrL[0];
+	else {
+		pwr_i = pwrL[0];
+		do {
+			pwr_i--;
+			tmp = (s8) ath5k_get_interpolated_value(pwr_i,
+							pwrL[0], pwrL[1],
+							stepL[0], stepL[1]);
+		} while (tmp > 1);
+
+		min_pwrL = pwr_i;
+	}
 
-	min_pwrR = pwr_i;
+	if (pwrR[0] == pwrR[1])
+		min_pwrR = pwrR[0];
+	else {
+		pwr_i = pwrR[0];
+		do {
+			pwr_i--;
+			tmp = (s8) ath5k_get_interpolated_value(pwr_i,
+							pwrR[0], pwrR[1],
+							stepR[0], stepR[1]);
+		} while (tmp > 1);
+
+		min_pwrR = pwr_i;
+	}
 
 	/* Keep the right boundary so that it works for both curves */
 	return max(min_pwrL, min_pwrR);