Intel Preps HWMON Support For Linux Driver To Expose Power / Voltage / Energy Reporting

Written by Michael Larabel in Intel on 12 August 2022 at 02:21 PM EDT. 2 Comments
While much of the Intel Arc Graphics "Alchemist" (DG2) support appears squared away for Linux 6.0 besides the support still being hidden behind the flag requiring i915.force_probe= to actually enable the experimental support, there still are various DG2 discrete GPU features being tackled by the open-source Intel kernel graphics drivers. One of those "extras" still working its way to the kernel is HWMON subsystem integration to be able to expose power / voltage / energy reporting.

Intel has been working on the i915 kernel driver to integrate with the hardware monitoring "HWMON" infrastructure so voltage, power, and energy values for their discrete graphics hardware can be exposed under Linux. Certainly not a requirement for every-day use but certainly nice to have for reviewers and enthusiasts wanting to analyze the power consumption and performance-per-Watt being achieved for Arc Graphics under Linux.

Thankfully Intel is working on this power reporting using HWMON so it jives nicely with existing Linux tools and monitoring solutions.

In addition to monitoring the metrics, the HWMON integration also allows setting an Intel graphics card's sustained PL1/Tau power limit in micro-Watts. In turn changing this value from the default will throttle the operating frequency if the power averaged over a window is exceeding that desired limit. This artificial down-clocking can be used for comparison purposes or trying to squeeze out extra efficiency in certain conditions.

The recently announced ASRock Challenger A380 graphics card.

This HWMON integration is too late for the 6.0 kernel cycle but hopefully will be all squared away in time for 6.1... Hopefully for 6.1 we'll see the experimental flag on DG2 removed too if all goes well to ensure that when these Arc Graphics desktop graphics cards are shipping in major markets later this year that they'll hopefully see out-of-the-box Linux support -- assuming you are riding the very latest kernel and Mesa, etc.

Those interested in all the details on the in-progress i915 HWMON integration can see this patch series.
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