intel: execlists — GPU execution list submission (Phase 4)
Add execlists.rs implementing GPU context submission via execlist ports.
- ExeclistPort: manages 2-slot ELSP (Execlist Submission Port)
at RING_ELSP (base + 0x230), context control (base + 0x244),
context status pointer (base + 0x3A0), and execlist control
(base + 0x550)
- init(): enable execlist control, configure context restore
inhibit + RS context enable, clear CSB pointer
- submit(): queue ExeclistContext to next available ELSP slot,
flush to hardware via ELSP register writes
- check_completion(): read RING_EXECLIST_STATUS_LO for completed
context count, update active counter
- create_lrc_descriptor(): allocate 4KB LRC in GGTT with
ELSP_VALID + ELSP_PRIVILEGE_ACCESS flags
Linux reference: intel_execlists_submission.c, i915_reg.h (ELSP)
vasilito
a60917387f