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From:   Sathishkumar Muruganandam <murugana@codeaurora.org>
To:     ath10k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org,
        Sathishkumar Muruganandam <murugana@codeaurora.org>
Subject: [PATCH] ath10k: fix VHT NSS calculation when STBC is enabled
Date:   Fri, 14 Aug 2020 13:46:11 +0530
Message-Id: <1597392971-3897-1-git-send-email-murugana@codeaurora.org>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

When STBC is enabled, NSTS_SU value need to be accounted for VHT NSS
calculation for SU case.

Without this fix, 1SS + STBC enabled case was reported wrongly as 2SS
in radiotap header on monitor mode capture.

Tested-on: QCA9984 10.4-3.10-00047

Signed-off-by: Sathishkumar Muruganandam <murugana@codeaurora.org>
---
 drivers/net/wireless/ath/ath10k/htt_rx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
index 69ad4ca1a87c..a00498338b1c 100644
--- a/drivers/net/wireless/ath/ath10k/htt_rx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
@@ -949,6 +949,7 @@ static void ath10k_htt_rx_h_rates(struct ath10k *ar,
 	u8 preamble = 0;
 	u8 group_id;
 	u32 info1, info2, info3;
+	u32 stbc, nsts_su;
 
 	info1 = __le32_to_cpu(rxd->ppdu_start.info1);
 	info2 = __le32_to_cpu(rxd->ppdu_start.info2);
@@ -993,11 +994,16 @@ static void ath10k_htt_rx_h_rates(struct ath10k *ar,
 		 */
 		bw = info2 & 3;
 		sgi = info3 & 1;
+		stbc = (info2 >> 3) & 1;
 		group_id = (info2 >> 4) & 0x3F;
 
 		if (GROUP_ID_IS_SU_MIMO(group_id)) {
 			mcs = (info3 >> 4) & 0x0F;
-			nss = ((info2 >> 10) & 0x07) + 1;
+			nsts_su = ((info2 >> 10) & 0x07);
+			if (stbc)
+				nss = (nsts_su >> 2) + 1;
+			else
+				nss = (nsts_su + 1);
 		} else {
 			/* Hardware doesn't decode VHT-SIG-B into Rx descriptor
 			 * so it's impossible to decode MCS. Also since
-- 
2.7.4