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nvidia-guide.md

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NVIDIA graphics cards

Driver API and source code available in liquidctl.driver.nvidia.

Support for these cards in only available on Linux. Other requirements must also be met:

  • i2c-dev kernel module has been loaded
  • r/w permissions to card-specific /dev/i2c-* devices
  • specific unsafe features have been opted in

Jump to a specific section:

EVGA GTX 1080 FTW

Only RGB lighting supported.

Unsafe features:

Initialization

Not required for this device.

Retrieving the current RGB lighting mode and color

In verbose mode status reports the current RGB lighting settings.

# liquidctl status --verbose --unsafe=smbus
EVGA GTX 1080 FTW
├── Mode      Fixed  
└── Color    2aff00

Controlling the LED

This GPU only has one led that can be set. The table bellow summarizes the available channels, modes and their associated number of required colors.

Channel Mode Colors
led off 0
led fixed 1
led breathing 1
led rainbow 0 
# liquidctl set led color off --unsafe=smbus
# liquidctl set led color rainbow --unsafe=smbus
# liquidctl set led color fixed ff8000 --unsafe=smbus
# liquidctl set led color breathing "hsv(90,85,70)" --unsafe=smbus
                ^^^       ^^^^^^^^^  ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^
              channel        mode        color     unsafe features

The LED color can be specified using any of the supported formats.

The settings configured on the device are normally volatile, and are cleared whenever the graphics card is powered down (OS and UEFI power saving settings can affect when this happens).

It is possible to store them in non-volatile controller memory by passing --non-volatile. But as this memory has some unknown yet limited maximum number of write cycles, volatile settings are preferable, if the use case allows for them.

# liquidctl set led color fixed 00ff00 --non-volatile --unsafe=smbus

ASUS Strix GTX and RTX

Only RGB lighting supported.

Unsafe features:

Initialization

Not required for this device.

Retrieving the current color mode and LED color

In verbose mode status reports the current RGB lighting settings.

# liquidctl status --verbose --unsafe=smbus
ASUS Strix RTX 2080 Ti OC
├── Mode      Fixed  
└── Color    ff0000

Controlling the LED

This GPU only has one led that can be set. The table bellow summarizes the available channels, modes, and their associated maximum number of colors for each device family.

Channel Mode Colors
led off 0
led fixed 1
led flash 1
led breathing 1
led rainbow 0 
# liquidctl set led color off --unsafe=smbus
# liquidctl set led color rainbow --unsafe=smbus
# liquidctl set led color fixed ff8000 --unsafe=smbus
# liquidctl set led color flash ff8000 --unsafe=smbus
# liquidctl set led color breathing "hsv(90,85,70)" --unsafe=smbus
                ^^^       ^^^^^^^^^  ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^
              channel        mode        color     unsafe features

The LED color can be specified using any of the supported formats.

The settings configured on the device are normally volatile, and are cleared whenever the graphics card is powered down (OS and UEFI power saving settings can affect when this happens).

It is possible to store them in non-volatile controller memory by passing --non-volatile. But as this memory has some unknown yet limited maximum number of write cycles, volatile settings are preferable, if the use case allows for them.

# liquidctl set led color fixed 00ff00 --non-volatile --unsafe=smbus

Note: The off mode is simply an alias for fixed 000000.

Inherent unsafeness of I2C

Reading and writing to I²C buses is inherently more risky than dealing with, for example, USB devices. On typical desktop and workstation systems many important chips are connected to these buses, and they may not tolerate writes or reads they do not expect.

It is necessary to rely on certain devices being know to use a specific address, or being documented/specified to do so; but there is always some risk that another, unexpected, device is using that same address.

On top of this, accessing I²C buses concurrently, from multiple threads or processes, may also result in undesirable or unpredictable behavior.

Unsurprisingly, users or programs dealing with I²C devices have occasionally crashed systems and even bricked boards or peripherals. In some cases this is reversible, but not always.

For all of these reasons liquidctl requires users to opt into accessing I²C and SMBus devices, both of which can be done by enabling the smbus unsafe feature. Other unsafe features may also be required for the use of specific devices, based on other know risks specific to a particular device.

Note that a feature not being labeled unsafe, or a device not requiring the use of additional unsafe features, does in no way assure that it is safe. This is especially true when dealing with I²C/SMBus devices.

Finally, liquidctl may list some I²C/SMBus devices even if smbus has not been enabled, but only if it is able to discover them without communicating with the bus or the devices.