Updated to 4.14.26-bone13 and cannot get PCA9544 I2C-mux to initialize, ideas?

[bglaz...@gmail.com]

We have had a solution running on 4.1.19-bone20 kernel for over a year. Now I am trying to add battery controlled shutdown to the Bone but came to the conclusion that the unit treats power removal as a push button event and immediately powers down. This doesn't work for our application, we need to be able to control the shutdown. After some scrounging around Groups I saw the (https://groups.google.com/forum/#!topic/beagleboard/DfkWz9qlqA8) problem was that the tps65217 kernel code needed modification. I decided to update to the latest kernel (4.14.26-bone13) to see if it was resolved. I did that and it is indeed fixed. Now I have to re-work my Device Tree Blob for this kernel.

No problem, I downloaded the kernel source and made by changes and compiled it. I moved the dtb to the Bone and rebooted. Everything comes online as expected except the PCA9544 I2C mux.

I checked dmesg and there are no entries, good or bad, relating to the mux.

According to /Kernel/Documentation/devicetree/bindings/i2c/i2c-mux.txt, nothing should have dramatically changed between the two kernels. 
After much experimentation, trying the various options, etc, I've decided to seek help.

Here is my entry made in am335x-bone-common.dtsi.

&i2c1 {

#address-cells = <1>;

#size-cells = <0>;

clock-frequency = <400000>;

status = "okay";

pinctrl-names = "default";

pinctrl-0 = <&i2c1_pins>;

mux@70 {

    #address-cells = <1>;

    #size-cells = <0>;

    compatible = "nxp,pca9544";

    reg = <0x70>;

    i2c@3 {

        #address-cells = <1>;

        #size-cells = <0>;

reg = <0x03>;

};

    i2c@4 {

#address-cells = <1>;

        #size-cells = <0>;

reg = <0x04>;

};

    i2c@5 {

#address-cells = <1>;

        #size-cells = <0>;

reg = <0x05>; 

    };

    i2c@6 {

#address-cells = <1>;

        #size-cells = <0>;

reg = <0x06>;

    };

    };

};

I can confirm that the mux is available and functioning using i2cget/set commands.

Can anyone recommend an approach to troubleshoot this further? Any useful logs that I am not seeing?

Also just for reference, this is how I had the entry structured on 4.1.19-bone20 before changing it to what is shown above.

&i2c1 {

pinctrl-names = "default";

pinctrl-0 = <&i2c1_pins>;

status = "okay";

clock-frequency = <400000>;

mux@70 {

compatible = "nxp,pca9544";

#address-cells = <1>;

#size-cells = <0>;

reg = <0x70>;

};

};

Thank you!

Bruce

[Graham]

Which bus and I-O pins is your Mux located on?

--- Graham

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