linux-kernel - Re: [PATCH v2 2/2] arm64: dts: qcom: qrb4210-rb2: switch I2C2 to i2c-gpio

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Date: Wed, 5 Jun 2024 13:44:50 +0200
From: Caleb Connolly <caleb.connolly@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 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: Alexey Klimov <alexey.klimov@...aro.org>, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH v2 2/2] arm64: dts: qcom: qrb4210-rb2: switch I2C2 to
 i2c-gpio



On 05/06/2024 10:55, Dmitry Baryshkov wrote:
> 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>

Reviewed-by: Caleb Connolly <caleb.connolly@...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..cb8a62714a30 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: i2c {
> +		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";
>   
> 

-- 
// Caleb (they/them)