mac80211: ath10k: fix latency issue for QCA988x

This backport fixes high latency (>100ms) on the WiFi link when using a
QCA988x Wave 1 radio. The ath10k-ct driver is not affected by this bug
from my testing, hence why it hasn't been discovered earlier.

Signed-off-by: David Bauer <mail@david-bauer.net>

package/kernel/mac80211/patches/ath/982-ath10k-fix-latency-issue-for-QCA988x.patch

@@ -0,0 +1,42 @@
+From: Miaoqing Pan <miaoqing@codeaurora.org>
+Subject: [PATCH] ath10k: fix latency issue for QCA988x
+Date: Thu, 29 Aug 2019 10:45:12 +0800
+
+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>
+---
+ 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
+@@ -2124,12 +2124,15 @@ 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;