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>

diff --git a/package/kernel/mac80211/patches/ath/982-ath10k-fix-latency-issue-for-QCA988x.patch b/package/kernel/mac80211/patches/ath/982-ath10k-fix-latency-issue-for-QCA988x.patch
new file mode 100644 (file)
index 0000000..3702abb
--- /dev/null
+++ b/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;