drm/xe/pf: Initialize scheduler groups

drm/xe/pf: Initialize scheduler groups

Scheduler groups (a.k.a. Engine Groups Scheduling, or EGS) is a GuC
feature that allows the driver to define groups of engines that are
independently scheduled across VFs, which allows different VFs to be
active on the HW at the same time on different groups. The feature is
available for BMG and newer HW starting on GuC 70.53.0, but some
required fixes have been added to GuC 70.55.1.

This is intended for specific scenarios where the admin knows that the
VFs are not going to fully utilize the HW and therefore assigning all of
it to a single VF would lead to part of it being permanently idle.
We do not allow the admin to decide how to divide the engines across
groups, but we instead support specific configurations that are designed
for specific use-cases. During PF initialization we detect which
configurations are possible on a given GT and create the relevant
groups. Since the GuC expect a mask for each class for each group, that
is what we save when we init the configs.

Right now we only have one use-case on the media GT. If the VFs are
running a frame render + encoding at a not-too-high resolution (e.g.
1080@30fps) the render can produce frames faster than the video engine
can encode them, which means that the maximum number of parallel VFs is
limited by the VCS bandwidth. Since our products can have multiple VCS
engines, allowing multiple VFs to be active on the different VCS engines
at the same time allows us to run more parallel VFs on the same HW.
Given that engines in the same media slice share some resources (e.g.
SFC), we assign each media slice to a different scheduling group. We
refer to this configuration as "media_slices", given that each slice
gets its own group. Since upcoming products have a different number of
video engines per-slice, for now we limit the media_slices mode to BMG,
but we expect to add support for newer HW soon.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251218223846.1146344-17-daniele.ceraolospurio@intel.com