linux-kernel - Re: [PATCH 5/6] arm64: dts: ls208xa-rdb: fix errata E-00013

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Message-ID: <20220410012543.GJ129381@dragon>
Date:   Sun, 10 Apr 2022 09:25:43 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Li Yang <leoyang.li@....com>
Cc:     Rob Herring <robh+dt@...nel.org>, Biwen Li <biwen.li@....com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] arm64: dts: ls208xa-rdb: fix errata E-00013

On Thu, Mar 17, 2022 at 02:01:08PM -0500, Li Yang wrote:
> From: Biwen Li <biwen.li@....com>
> 
> Specify a channel zero in idle state to
> avoid enterring tri-stated state for PCA9547.

Please check Documentation/process/submitting-patches.rst for commit log
wrapping requirement.

> About E-00013:
> 	- Description: I2C1 and I2C3 buses

Use space instead of tab for bullet indent.

Shawn

> 	  are missing pull-up.
> 	- Impact: When the PCA954x device is tri-stated, the I2C bus
> 	  will float. This makes the I2C bus and its associated
> 	  downstream devices inaccessible.
> 	- Hardware fix: Populate resistors R189 and R190 for I2C1
> 	  and resistors R228 and R229 for I2C3.
> 	- Software fix: Remove the tri-state option from the PCA954x
> 	  driver(PCA954x always on enable status, specify a
> 	  channel zero in dts to fix the errata E-00013).
> 
> Signed-off-by: Biwen Li <biwen.li@....com>
> Signed-off-by: Li Yang <leoyang.li@....com>
> ---
>  arch/arm64/boot/dts/freescale/fsl-ls208xa-rdb.dtsi | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/fsl-ls208xa-rdb.dtsi b/arch/arm64/boot/dts/freescale/fsl-ls208xa-rdb.dtsi
> index 4b71c4fcb35f..a752f06a2e74 100644
> --- a/arch/arm64/boot/dts/freescale/fsl-ls208xa-rdb.dtsi
> +++ b/arch/arm64/boot/dts/freescale/fsl-ls208xa-rdb.dtsi
> @@ -49,6 +49,8 @@ pca9547@75 {
>  		reg = <0x75>;
>  		#address-cells = <1>;
>  		#size-cells = <0>;
> +		idle-state = <0>;
> +
>  		i2c@1 {
>  			#address-cells = <1>;
>  			#size-cells = <0>;
> -- 
> 2.25.1
>