UAPI Changes:
- drm/i915/guc: Use context hints for GT frequency
Allow user to provide a low latency context hint. When set, KMD
sends a hint to GuC which results in special handling for this
context. SLPC will ramp the GT frequency aggressively every time
it switches to this context. The down freq threshold will also be
lower so GuC will ramp down the GT freq for this context more slowly.
We also disable waitboost for this context as that will interfere with
the strategy.
We need to enable the use of SLPC Compute strategy during init, but
it will apply only to contexts that set this bit during context
creation.
Userland can check whether this feature is supported using a new param-
I915_PARAM_HAS_CONTEXT_FREQ_HINT. This flag is true for all guc submission
enabled platforms as they use SLPC for frequency management.
The Mesa usage model for this flag is here -
https://gitlab.freedesktop.org/sushmave/mesa/-/commits/compute_hint
- drm/i915/gt: Enable only one CCS for compute workload
Enable only one CCS engine by default with all the compute sices
allocated to it.
While generating the list of UABI engines to be exposed to the
user, exclude any additional CCS engines beyond the first
instance
***
NOTE: This W/A will make all DG2 SKUs appear like single CCS SKUs by
default to mitigate a hardware bug. All the EUs will still remain
usable, and all the userspace drivers have been confirmed to be able
to dynamically detect the change in number of CCS engines and adjust.
For the smaller percent of applications that get perf benefit from
letting the userspace driver dispatch across all 4 CCS engines we will
be introducing a sysfs control as a later patch to choose 4 CCS each
with 25% EUs (or 50% if 2 CCS).
NOTE: A regression has been reported at
https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10895
However Andi has been triaging the issue and we're closing in a fix
to the gap in the W/A implementation:
https://lists.freedesktop.org/archives/intel-gfx/2024-April/348747.html
Driver Changes:
- Add new and fix to existing workarounds: Wa_14018575942 (MTL),
Wa_16019325821 (Gen12.70), Wa_14019159160 (MTL), Wa_16015675438,
Wa_14020495402 (Gen12.70) (Tejas, John, Lucas)
- Fix UAF on destroy against retire race and remove two earlier
partial fixes (Janusz)
- Limit the reserved VM space to only the platforms that need it (Andi)
- Reset queue_priority_hint on parking for execlist platforms (Chris)
- Fix gt reset with GuC submission is disabled (Nirmoy)
- Correct capture of EIR register on hang (John)
- Remove usage of the deprecated ida_simple_xx() API
- Refactor confusing __intel_gt_reset() (Nirmoy)
- Fix the fix for GuC reset lock confusion (John)
- Simplify/extend platform check for Wa_14018913170 (John)
- Replace dev_priv with i915 (Andi)
- Add and use gt_to_guc() wrapper (Andi)
- Remove bogus null check (Rodrigo, Dan)
. Selftest improvements (Janusz, Nirmoy, Daniele)