Intel Idle Support For Granite Rapids D Going Into Linux 6.13

The "intel_idle" driver provides CPU idle time management for Intel processors on Linux for helping to put the processor into low-power states in conjunction with the MWAIT instruction. With the upcoming Linux 6.13 kernel, the Granite Rapids D support for the Intel Idle driver is set to be merged.

Intel Idle already supports Granite Rapids while for Linux 6.13 it's being extended to support Granite Rapids D, the Xeon 6 SoC intended for edge computing and the successor to aging Ice Lake D processors. We've seen various elements of Granite Rapids D support arrive for the Linux kernel and other open-source components over the past year while it appears a few bits remain such as this intel_idle support.

Sent out last week was the patch for Granite Rapids-D with Intel_Idle:

"Add Granite Rapids Xeon C C-states support: C1, C1E, C6, and C6P.

The C-states are basically the same as in Granite Rapids Xeon SP/AP, but characteristics (latency, target residency) are a bit different."

Compared to Granite Rapids, the Granite Rapids D patch indicates higher exit latency from C6 at 220 compared to 170 with Granite Rapids. The C6 exit latency back on Ice Lake was 170 as another reference point to this Ice Lake D successor. The C6P exit latency is also higher on GNR-D at 240 compared to 210 with GNR.

This Intel Granite Rapids D support in intel_idle is already queued up as part of the power management changes coming with the Linux 6.13 merge window beginning next week. Linux 6.13 will see its stable release in late January or early 2025 while Granite Rapids-D is expected sometime in 2025. This intel_idle patch is also simple enough for back-porting to prior kernel versions.