[Intel-gfx] [RFC] GPU-bound energy efficiency improvements for the intel_pstate driver (v2.99)

[Francisco Jerez]

This addresses the technical concerns people brought up about my
previous v2 revision of this series.  Other than a few bug fixes, the
only major change relative to v2 is that the controller is now exposed
as a new CPUFREQ generic governor as requested by Rafael (named
"adaptive" in this RFC though other naming suggestions are welcome).
Main reason for calling this v2.99 rather than v3 is that I haven't
yet addressed all the documentation requests from the v2 thread --
Will spend some time doing that as soon as I have an ACK (ideally from
Rafael) that things are moving in the right direction.

You can also find this series along with the WIP code for non-HWP
platforms in this branch:

https://github.com/curro/linux/tree/intel_pstate-vlp-v2.99

Thanks!

[PATCHv2.99 01/11] PM: QoS: Add CPU_SCALING_RESPONSE global PM QoS limit.
[PATCHv2.99 02/11] drm/i915: Adjust PM QoS scaling response frequency based on GPU load.
[PATCHv2.99 03/11] OPTIONAL: drm/i915: Expose PM QoS control parameters via debugfs.
[PATCHv2.99 04/11] cpufreq: Define ADAPTIVE frequency governor policy.
[PATCHv2.99 05/11] cpufreq: intel_pstate: Reorder intel_pstate_clear_update_util_hook() and intel_pstate_set_update_util_hook().
[PATCHv2.99 06/11] cpufreq: intel_pstate: Call intel_pstate_set_update_util_hook() once from the setpolicy hook.
[PATCHv2.99 07/11] cpufreq: intel_pstate: Implement VLP controller statistics and target range calculation.
[PATCHv2.99 08/11] cpufreq: intel_pstate: Implement VLP controller for HWP parts.
[PATCHv2.99 09/11] cpufreq: intel_pstate: Enable VLP controller based on ACPI FADT profile and CPUID.
[PATCHv2.99 10/11] OPTIONAL: cpufreq: intel_pstate: Add tracing of VLP controller status.
[PATCHv2.99 11/11] OPTIONAL: cpufreq: intel_pstate: Expose VLP controller parameters via debugfs.