0x40 I2C Address Conflict on Nvidia AGX and some GMSL cameras

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
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1

Hi
I got a question about Nvidia AGX to support new GMSL camera issue.
We have a GMSL camera, where it’s serializer chip’s I2C address is 0x40.

But I notice there’s an existing I2C 0x40 and 0x41 at /dev/i2c-1.
We did use a TCA9546 for a I2C Mux, and remap the 4 deserializer and serializer channels to bus 30. e.g. /dev/i2c-30, /dev/i2c-31, /dev/i2c-32, /dev/i2c-33.
But when I tried to access /dev/i2c-30, the “upstream” i2c devices like 0x40, and 0x41 are still exist at my /dev/i2c-30. This makes my GMSL camera (0x40) undetectable.
Does any one solve this issue before ?

3

You can modify the force_bus_start to adjust the start bus of MUX to clarify it.

                tca9546@70 {
                        compatible = "nxp,pca9546";
                        reg = <0x70>;
                        #address-cells = <0x1>;
                        #size-cells = <0x0>;
                        vcc-supply = <0x2d>;
                        skip_mux_detect = "yes";
                        force_bus_start = <0x1e>;
                        vcc_lp = "vcc";
                        vif-supply = <0x2d>;
                        status = "disabled";
                        linux,phandle = <0xf3>;
                        phandle = <0xf3>;