linux-kernel - [PATCH 2/2] arm64: dts: qcom: qrb4210-rb2: switch I2C2 to i2c-gpio

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Message-Id: <20240604-rb12-i2c2g-pio-v1-2-f323907179d9@linaro.org>
Date: Tue, 04 Jun 2024 13:14:59 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konrad.dybcio@...aro.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Caleb Connolly <caleb.connolly@...aro.org>, 
 Alexey Klimov <alexey.klimov@...aro.org>, linux-arm-msm@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, stable@...r.kernel.org
Subject: [PATCH 2/2] arm64: dts: qcom: qrb4210-rb2: switch I2C2 to i2c-gpio

On the Qualcomm RB2 platform the I2C bus connected to the LT9611UXC
bridge under some circumstances can go into a state when all transfers
timeout. This causes both issues with fetching of EDID and with
updating of the bridge's firmware. While we are debugging the issue,
switch corresponding I2C bus to use i2c-gpio driver. While using
i2c-gpio no communication issues are observed.

This patch is asusmed to be a temporary fix, so it is implemented in a
non-intrusive manner to simply reverting it later.

Fixes: f7b01e07e89c ("arm64: dts: qcom: qrb4210-rb2: Enable display out")
Cc: stable@...r.kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 arch/arm64/boot/dts/qcom/qrb4210-rb2.dts | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/qrb4210-rb2.dts b/arch/arm64/boot/dts/qcom/qrb4210-rb2.dts
index 2c39bb1b97db..5bfbd81db032 100644
--- a/arch/arm64/boot/dts/qcom/qrb4210-rb2.dts
+++ b/arch/arm64/boot/dts/qcom/qrb4210-rb2.dts
@@ -60,6 +60,17 @@ hdmi_con: endpoint {
 		};
 	};
 
+	i2c2_gpio: i2c2-gpio {
+		compatible = "i2c-gpio";
+
+		sda-gpios = <&tlmm 6 GPIO_ACTIVE_HIGH>;
+		scl-gpios = <&tlmm 7 GPIO_ACTIVE_HIGH>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		status = "disabled";
+	};
+
 	leds {
 		compatible = "gpio-leds";
 
@@ -190,7 +201,7 @@ zap-shader {
 	};
 };
 
-&i2c2 {
+&i2c2_gpio {
 	clock-frequency = <400000>;
 	status = "okay";
 

-- 
2.39.2