All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
To: agross@kernel.org, bjorn.andersson@linaro.org
Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Subject: [PATCH v2] arm64: dts: qcom: msm8998: Fixup uart3 gpio config for bluetooth
Date: Mon, 21 Oct 2019 09:19:21 -0700	[thread overview]
Message-ID: <20191021161921.31825-1-jeffrey.l.hugo@gmail.com> (raw)

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>
---

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


             reply	other threads:[~2019-10-21 16:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 16:19 Jeffrey Hugo [this message]
2019-10-21 19:58 ` [PATCH v2] arm64: dts: qcom: msm8998: Fixup uart3 gpio config for bluetooth Matthias Kaehlcke
2019-10-21 20:28   ` Jeffrey Hugo
2019-10-21 20:51     ` Matthias Kaehlcke

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191021161921.31825-1-jeffrey.l.hugo@gmail.com \
    --to=jeffrey.l.hugo@gmail.com \
    --cc=agross@kernel.org \
    --cc=bjorn.andersson@linaro.org \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.