drm/xe/uapi: Use hint for guc to set GT frequency

Allow user to provide a low latency hint. When set, KMD sends a hint
to GuC which results in special handling for that process. SLPC will
ramp the G

drm/xe/uapi: Use hint for guc to set GT frequency

Allow user to provide a low latency hint. When set, KMD sends a hint
to GuC which results in special handling for that process. SLPC will
ramp the GT frequency aggressively every time it switches to this
process.

We need to enable the use of SLPC Compute strategy during init, but
it will apply only to processes that set this bit during process
creation.

Improvement with this approach as below:

Before,

:~$ NEOReadDebugKeys=1 EnableDirectSubmission=0 clpeak --kernel-latency
Platform: Intel(R) OpenCL Graphics
Device: Intel(R) Graphics [0xe20b]
Driver version : 24.52.0 (Linux x64)
Compute units : 160
Clock frequency : 2850 MHz
Kernel launch latency : 283.16 us

After,

:~$ NEOReadDebugKeys=1 EnableDirectSubmission=0 clpeak --kernel-latency
Platform: Intel(R) OpenCL Graphics
Device: Intel(R) Graphics [0xe20b]
Driver version : 24.52.0 (Linux x64)
Compute units : 160
Clock frequency : 2850 MHz

Kernel launch latency : 63.38 us

Compute PR: https://github.com/intel/compute-runtime/pull/794
Mesa PR: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33214
IGT PR: https://patchwork.freedesktop.org/patch/639989/

V10(Lucas):
- Remove doc from drm-uapi.rst
v9(Vinay):
- remove extra line, align commit message
v8(Vinay):
- Add separate example for using low latency hint
v7(Jose):
- Update UMD PR
- applicable to all gpus
V6:
- init flags, remove redundant flags check (MAuld)
V5:
- Move uapi doc to documentation and GuC ABI specific change (Rodrigo)
- Modify logic to restrict exec queue flags (MAuld)
V4:
- To make it clear, dont use exec queue word (Vinay)
- Correct typo in description of flag (Jose/Vinay)
- rename set_strategy api and replace ctx with exec queue(Vinay)
- Start with 0th bit to indentify user flags (Jose)
V3:
- Conver user flag to kernel internal flag and use (Oak)
- Support query config for use to check kernel support (Jose)
- Dont need to take runtime pm (Vinay)
V2:
- DRM_XE_EXEC_QUEUE_LOW_LATENCY_HINT 1 planned for other hint(Szymon)
- Add motivation to description (Lucas)

Acked-by: Lucas De Marchi <[email protected]>
Reviewed-by: Vinay Belgaumkar <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Tejas Upadhyay <[email protected]>

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