I2C Communication with NVIDIA Cards

I2C Communication with NVIDIA Cards

https://www.ddcutil.com/nvidia/

When using Nvidia’s proprietary driver, I2C communication fails on some cards. This has been the topic of some discussion on Nvidia’s web site. See, for example.

While not a universal solution, setting undocumented Nvidia options sometimes enables I2C communication to work. There are several ways to set these options. The simplest, outlined in a post by user arcnmx, puts the settings in /etc/modprobe.d. Add a file whose name ends in “.conf” to that directory, e.g. /etc/modprobe.d/nvidia_i2c.conf. The file should contain the following:

options nvidia NVreg_RegistryDwords=RMUseSwI2c=0x01;RMI2cSpeed=100

After rebooting, confirm that the settings have been applied:

    $ grep RegistryDwords /proc/driver/nvidia/params
    RegistryDwords: "RMUseSwI2c=0x01;RMI2cSpeed=100"

An earlier version of this page discussed how to set the options using a file in /etc/X11/xorg.conf.d. It has been retained for reference as it may be useful if the /etc/modprobe.d method is not suitable for your setup.