[PATCH] arm64: dts: qcom: msm8998: Fixup uart3 gpio config for bluetooth

[Jeffrey Hugo <jeffrey.l.hugo@gmail.com>]

It turns out that the wcn3990 can float the gpio lines during bootup, etc
which will result in the uart core thinking there is incoming data.  This
results in the bluetooth stack getting garbage.  By applying a bias to
match what wcn3990 would drive, the issue is corrected.

Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
---
 .../boot/dts/qcom/msm8998-clamshell.dtsi      | 31 +++++++++++++++++++
 arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi     | 31 +++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
index ab24d415acc0..7e02cb6c8e07 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
@@ -74,6 +74,37 @@
 	};
 };
 
+&blsp1_uart3_on {
+	/delete-node/ config;
+
+	pinconf-cts {
+		/*
+		 * Configure a pull-down on 47 (CTS) to match the pull
+		 * of the Bluetooth module.
+		 */
+		pins = "gpio47";
+		bias-pull-down;
+	};
+
+	pinconf-rts-tx {
+		/* We'll drive 48 (RFR) and 45 (TX), so no pull */
+		pins = "gpio45", "gpio48";
+		drive-strength = <2>;
+		bias-disable;
+	};
+
+	pinconf-rx {
+		/*
+		 * Configure a pull-up on 45 (RX). This is needed to
+		 * avoid garbage data when the TX pin of the Bluetooth
+		 * module is in tri-state (module powered off or not
+		 * driving the signal yet).
+		 */
+		pins = "gpio45";
+		bias-pull-up;
+	};
+};
+
 &dsi0 {
 	status = "okay";
 
diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
index 1a1836ed1052..17f51af5e999 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
@@ -37,6 +37,37 @@
 	};
 };
 
+&blsp1_uart3_on {
+	/delete-node/ config;
+
+	pinconf-cts {
+		/*
+		 * Configure a pull-down on 47 (CTS) to match the pull
+		 * of the Bluetooth module.
+		 */
+		pins = "gpio47";
+		bias-pull-down;
+	};
+
+	pinconf-rts-tx {
+		/* We'll drive 48 (RFR) and 45 (TX), so no pull */
+		pins = "gpio45", "gpio48";
+		drive-strength = <2>;
+		bias-disable;
+	};
+
+	pinconf-rx {
+		/*
+		 * Configure a pull-up on 45 (RX). This is needed to
+		 * avoid garbage data when the TX pin of the Bluetooth
+		 * module is in tri-state (module powered off or not
+		 * driving the signal yet).
+		 */
+		pins = "gpio45";
+		bias-pull-up;
+	};
+};
+
 &blsp2_uart1 {
 	status = "okay";
 };
-- 
2.17.1