Linux 6.13 To Allow Controlling Zero RPM Feature For Radeon RX 7000 Series GPUs

Sent out yesterday was an AMDGPU/AMDKFD kernel driver pull request with the last few feature additions and patches slated for the upcoming Linux 6.13 kernel merge window. Alongside other AMD kernel graphics driver updates, the new driver code with Radeon RX 7000 series RDNA3 graphics cards will finally allow controlling the zero RPM fan feature under Linux.

With this latest round of AMDGPU updates for Linux 6.13 are a number of DCN 3.5.x and DCN 4.x display fixes, various 8K display fixes, OLED fixes, code clean-ups, and other mostly maintenance work. For end-users one item worth mentioning though is user control for the zero RPM feature on graphics cards with the SMU13 IP, i.e. the Radeon RX 7000 series.

The AMD "zero RPM" fan feature allows for the graphics card's fan to be completely stopped when idle / below set temperature thresholds. With the Radeon Software for Windows driver the zero RPM fan control can be toggled via a GUI option... But not so under Linux until now. With Linux 6.13 new sysfs entries are being added to be allow users to toggle whether they want this feature or not and to specify the temperature threshold for when zero RPM should be engaged.

The new AMDGPU "fan_zero_rpm" sysfs file on Radeon RX 7000 series graphics cards allow users to find their zero RPM fan status and/or write to the file for controlling its behavior.

A second patch adds the "fan_zero_rpm_stop_temperature" sysfs file for reading or setting the temperature at which the graphics card fan should stop if the zero RPM feature is enabled.

This code ended up being written by a user, Wolfgang Müller, who wanted to get the zero RPM fan controls working for his Radeon RX 7900 XTX graphics card. Wolfgang explained on one of the patches:

"I've been wanting this feature for a while so today I sat down and had a look at how to best implement it. This is my first ever look at amdgpu code, so I've marked it with RFC. I've based it on the implementation of eedd5a343d22 (drm/amd/pm: add fan target temperature OD setting support for SMU13, 2023-08-11) and also hooked resetting the knob with "r"."

There has also been a bug report open for several months pertaining to the lack of the zero RPM fan control under Linux where as with the Windows 11 driver is a GUI toggle. With the upcoming Linux 6.13 cycle, this option is finally in place albeit as a sysfs file that users will need to control from the terminal or otherwise script/integrate its behavior with other software.

See this pull request for these final feature patches queued ahead of the Linux 6.13 merge window.