An i2c issue found in intel-bmc/openbmc

[郁雷]

This email is to introduce an issue related to i2c found on
intel-bmc/openbmc[1].

I am working on a machine that is based on intel-bmc/openbmc, and it
has a pca9555 GPIO expander on i2c-8.

The dts looks like below:

  &i2c8 {
    status = "okay";
    pca0:pca9555 at 24 {
      compatible = "nxp,pca9555";
      reg = <0x24>;
      #address-cells = <1>;
      #size-cells = <0>;
      gpio-controller;
      #gpio-cells = <2>;
    }
  }

If you have a similar setup, you may see the kernel gives below error:

    [    2.561952] pca953x 8-0024: failed writing register
    [    2.567061] pca953x: probe of 8-0024 failed with error -110

It turns out that the patch
0075-Refine-initialization-flow-in-I2C-driver.patch[2] caused the
issue. And if I revert the patch, the issue is gone.

A github issue is created at
https://github.com/Intel-BMC/openbmc/issues/48, hopefully Intel could
fix this issue :)

[1]: https://github.com/Intel-BMC/openbmc
[2]: https://github.com/Intel-BMC/openbmc/blob/intel/meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0075-Refine-initialization-flow-in-I2C-driver.patch