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Linux not detecting mux child i2c busses

rgb-sti

Hi,

In my custom Linux for Ultrazed, it does not detect the child i2c busses of the 9542 mux. I receive the following messages during boot.

[    1.559359] i2c /dev entries driver
[    1.563038] cdns-i2c ff030000.i2c: 400 kHz mmio ff030000 irq 32
[    1.569687] pca954x 0-0070: registered 0 multiplexed busses for I2C mux pca9542
 
If I use the AVNET oroginal sd card image, it detects the child busses.
 
I've copied the kconfig and system_user.dtsi from the petalinux bsp into my own Yocto project.
Unfortunately I get different results.
 
Any idea what else I could be missing?
 
Thanks,
 
Richard.
  • 0
     
      

    Hi Richard,

      

    Do you have any device entries for the I2C mux?

      

    This is what I have in my device tree:

      

    &i2c1 {
        status = "okay";
        clock-frequency = ;

      

    i2cswitch@70 { /* U7 on UZ3EG SOM */
        compatible = "nxp,pca9542";
        #address-cells = ;
        #size-cells = ;
        reg = ;
        i2c@0 { /* i2c mw 70 0 1 */
        #address-cells = ;
        #size-cells = ;
        reg = ;
        /* IIC_EEPROM */
        eeprom@51 { /* U5 on UZ3EG IOCC and U7 on the UZ7EV EVCC*/
        compatible = "at,24c08";
        reg = ;
        };
        };
        };
        };

      

    This is taken from here:

      

    https://github.com/Avnet/petalinux/blob/master/configs/device-tree/system-user.dtsi.UZ3EG_IOCC

      

    Best Regards,

      

    -Kevin

     
  • 0

    Hi Kevin,

    Thanks for the reply. Yes, I have that already. I have a custom Yocto, but I am using PetaLinux tools to generate the device tree and to generate the boot image. Then applying copying the device tree, AVNET's board level device tree settings, as you pointed to in their Github, using the PetaLinux generated configs to build my kernel image and rootfs.

    I'm struggling to find any difference between my configuration and the AVNET BSP.

    Thanks,

    Richard.

  • 0

    I've found the issue. The meta-xilinx layer I was using appears to relate to 2017.1 release. There was an update to the pca954x driver which resolves the issue. I'm not in a position to update the meta-xilinx layer right now, but applying a patch to the newer driver worked.

    [    1.550760] i2c /dev entries driver
    [    1.554445] cdns-i2c ff020000.i2c: 400 kHz mmio ff020000 irq 34
    [    1.560924] cdns-i2c ff030000.i2c: 400 kHz mmio ff030000 irq 35
    [    1.597693] i2c i2c-1: Added multiplexed i2c bus 2
    [    1.602625] i2c i2c-1: Added multiplexed i2c bus 3
    [    1.607343] pca954x 1-0070: registered 2 multiplexed busses for I2C mux pca9542
     
    Thanks,
     
    Richard.
  • 0

    Hi Richard,

    That is great news!  Thank you for sharing your findings with our community!

    Best Regards,

    -Kevin