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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Miaoqing Pan <miaoqing@codeaurora.org>,
        Kalle Valo <kvalo@codeaurora.org>
Subject: [PATCH 5.3 101/163] ath10k: fix latency issue for QCA988x
Date:   Mon,  4 Nov 2019 22:44:51 +0100
Message-Id: <20191104212147.383576170@linuxfoundation.org>
In-Reply-To: <20191104212140.046021995@linuxfoundation.org>
References: <20191104212140.046021995@linuxfoundation.org>
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From: Miaoqing Pan <miaoqing@codeaurora.org>

commit d79749f7716d9dc32fa2d5075f6ec29aac63c76d upstream.

(kvalo: cherry picked from commit 1340cc631bd00431e2f174525c971f119df9efa1 in
wireless-drivers-next to wireless-drivers as this a frequently reported
regression)

Bad latency is found on QCA988x, the issue was introduced by
commit 4504f0e5b571 ("ath10k: sdio: workaround firmware UART
pin configuration bug"). If uart_pin_workaround is false, this
change will set uart pin even if uart_print is false.

Tested HW: QCA9880
Tested FW: 10.2.4-1.0-00037

Fixes: 4504f0e5b571 ("ath10k: sdio: workaround firmware UART pin configuration bug")
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/ath/ath10k/core.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -2118,12 +2118,15 @@ static int ath10k_init_uart(struct ath10
 		return ret;
 	}
 
-	if (!uart_print && ar->hw_params.uart_pin_workaround) {
-		ret = ath10k_bmi_write32(ar, hi_dbg_uart_txpin,
-					 ar->hw_params.uart_pin);
-		if (ret) {
-			ath10k_warn(ar, "failed to set UART TX pin: %d", ret);
-			return ret;
+	if (!uart_print) {
+		if (ar->hw_params.uart_pin_workaround) {
+			ret = ath10k_bmi_write32(ar, hi_dbg_uart_txpin,
+						 ar->hw_params.uart_pin);
+			if (ret) {
+				ath10k_warn(ar, "failed to set UART TX pin: %d",
+					    ret);
+				return ret;
+			}
 		}
 
 		return 0;