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@xxxxxxxxx>
---
v2:
-split out pinctrl config by pin
.../boot/dts/qcom/msm8998-clamshell.dtsi | 22 ++++++++++++++++
arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 22 ++++++++++++++++
arch/arm64/boot/dts/qcom/msm8998-pins.dtsi | 25 ++++++++++++++++---
3 files changed, 65 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
index 38a1c2ba5e83..8c9a3e0f3843 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
@@ -37,6 +37,28 @@
};
};
+&blsp1_uart3_on {
+ rx {
+ /delete-property/ bias-disable;
+ /*
+ * 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).
+ */
+ bias-pull-up;
+ };
+
+ cts {
+ /delete-property/ bias-disable;
+ /*
+ * Configure a pull-down on 47 (CTS) to match the pull
+ * of the Bluetooth module.
+ */
+ bias-pull-down;
+ };
+};
+
&qusb2phy {
status = "okay";
diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
index 8adb4969baec..74c14f50b0f6 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
@@ -37,6 +37,28 @@
};
};
+&blsp1_uart3_on {
+ rx {
+ /delete-property/ bias-disable;
+ /*
+ * 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).
+ */
+ bias-pull-up;
+ };
+
+ cts {
+ /delete-property/ bias-disable;
+ /*
+ * Configure a pull-down on 47 (CTS) to match the pull
+ * of the Bluetooth module.
+ */
+ bias-pull-down;
+ };
+};
+
&blsp2_uart1 {
status = "okay";
};
diff --git a/arch/arm64/boot/dts/qcom/msm8998-pins.dtsi b/arch/arm64/boot/dts/qcom/msm8998-pins.dtsi
index e32d3ab395ea..7c222cbf19d9 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-pins.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-pins.dtsi
@@ -77,13 +77,30 @@
};
blsp1_uart3_on: blsp1_uart3_on {
- mux {
- pins = "gpio45", "gpio46", "gpio47", "gpio48";
+ tx {
+ pins = "gpio45";
function = "blsp_uart3_a";
+ drive-strength = <2>;
+ bias-disable;
};
- config {
- pins = "gpio45", "gpio46", "gpio47", "gpio48";
+ rx {
+ pins = "gpio46";
+ function = "blsp_uart3_a";
+ drive-strength = <2>;
+ bias-disable;
+ };
+
+ cts {
+ pins = "gpio47";
+ function = "blsp_uart3_a";
+ drive-strength = <2>;
+ bias-disable;
+ };
+
+ rfr {
+ pins = "gpio48";
+ function = "blsp_uart3_a";
drive-strength = <2>;
bias-disable;
};
--
2.17.1
