While it looked like Linux 6.17 was going to be a good baseline for support with upcoming Intel Panther Lake powered laptops given that this next kernel release ships with the Xe3 graphics enabled by default and other bits coming together, it looks like there is at least one late item only being presented today in patch form: a new “SoC Power Slider” feature as part of the Intel thermal driver for this new feature of Panther Lake SoCs.
Missing out on Linux 6.17, which is unfortunate since it will be the kernel powering the likes of Ubuntu 25.10, is this new SoC Power Slider feature being introduced with Panther Lake hardware. Sent out today on the Linux kernel mailing list is the first time I am seeing these patches presented.
The SoC Power Slider is a new system-wide energy performance preferences interface. This SoC Power Slider is piggy-backing off the Linux platform profile API. The patch introducing the notion of the SoC Power Slider explains:
“Add support for system wide energy performance preference using a SoC slider interface defined via processor thermal PCI device MMIO space.
Using Linux platform-profile class API, register a new platform profile. Provide three platform power profile choices: “performance”, “balanced” and “low-power”.
Profile sysfs is located at:
/sys/class/platform-profile/platform-profile-*
where attribute “name” is presented as “SoC Power Slider”.At boot by default the slider is set to balanced mode. This profile is changed by user space based on user preference via power profile daemon or directly writing to the “profile” sysfs attribute.
Add a CPU model specific processor thermal device feature PROC_THERMAL_FEATURE_SOC_POWER_SLIDER. When enabled for a CPU model, slider interface is registered.”
The preference is then conveyed to the SoC firmware for its handling of the performance / power preference and its internal SoC algorithms. This slider is on a 0 to 6 scale.
As mentioned, this new SoC Power Slider interface is premiering for the first time with Panther Lake. The int340x thermal driver also adds a new “slider_offset” module parameter to allow overriding the power slider default at boot time if not wanting balanced by default.
With the first Intel Panther Lake hardware expected to debut later this year, these Intel thermal driver patches for this SoC Power Slider feature are coming rather late and months after a lot of the other Panther Lake code was already upstreamed into the Linux kernel… Here’s to hoping this new patch series is reviewed well and will make it for the Linux 6.18 cycle, which will see its stable release in December.
