From: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Date: Tue, 14 Jan 2014 08:11:17 +0000 (+0530)
Subject: ath9k: Fix possible overflow condition
X-Git-Tag: firefly_0821_release~176^2~4570^2~3^2^2~14
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=3b24e9f8c07fc09174e4f2fe4d0f716595ae2146;p=firefly-linux-kernel-4.4.55.git

ath9k: Fix possible overflow condition

Prevent a possible overflow condition which results in occasional
bad IQ coefficients and EVM numbers.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
---

diff --git a/drivers/net/wireless/ath/ath9k/ar9003_calib.c b/drivers/net/wireless/ath/ath9k/ar9003_calib.c
index 4eb35aa64f35..a352128c40ad 100644
--- a/drivers/net/wireless/ath/ath9k/ar9003_calib.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_calib.c
@@ -565,7 +565,7 @@ static bool ar9003_hw_solve_iq_cal(struct ath_hw *ah,
 	const s32 result_shift = 1 << 15;
 	struct ath_common *common = ath9k_hw_common(ah);
 
-	f2 = (f1 * f1 + f3 * f3) / result_shift;
+	f2 = ((f1 >> 3) * (f1 >> 3) + (f3 >> 3) * (f3 >> 3)) >> 9;
 
 	if (!f2) {
 		ath_dbg(common, CALIBRATE, "Divide by 0\n");