xref: /openbmc/linux/Documentation/gpu/i915.rst (revision 908fc4c2)
1===========================
2 drm/i915 Intel GFX Driver
3===========================
4
5The drm/i915 driver supports all (with the exception of some very early
6models) integrated GFX chipsets with both Intel display and rendering
7blocks. This excludes a set of SoC platforms with an SGX rendering unit,
8those have basic support through the gma500 drm driver.
9
10Core Driver Infrastructure
11==========================
12
13This section covers core driver infrastructure used by both the display
14and the GEM parts of the driver.
15
16Runtime Power Management
17------------------------
18
19.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c
20   :doc: runtime pm
21
22.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c
23   :internal:
24
25.. kernel-doc:: drivers/gpu/drm/i915/intel_uncore.c
26   :internal:
27
28Interrupt Handling
29------------------
30
31.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
32   :doc: interrupt handling
33
34.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
35   :functions: intel_irq_init intel_irq_init_hw intel_hpd_init
36
37.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
38   :functions: intel_runtime_pm_disable_interrupts
39
40.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c
41   :functions: intel_runtime_pm_enable_interrupts
42
43Intel GVT-g Guest Support(vGPU)
44-------------------------------
45
46.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c
47   :doc: Intel GVT-g guest support
48
49.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c
50   :internal:
51
52Intel GVT-g Host Support(vGPU device model)
53-------------------------------------------
54
55.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c
56   :doc: Intel GVT-g host support
57
58.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c
59   :internal:
60
61Workarounds
62-----------
63
64.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_workarounds.c
65   :doc: Hardware workarounds
66
67Display Hardware Handling
68=========================
69
70This section covers everything related to the display hardware including
71the mode setting infrastructure, plane, sprite and cursor handling and
72display, output probing and related topics.
73
74Mode Setting Infrastructure
75---------------------------
76
77The i915 driver is thus far the only DRM driver which doesn't use the
78common DRM helper code to implement mode setting sequences. Thus it has
79its own tailor-made infrastructure for executing a display configuration
80change.
81
82Frontbuffer Tracking
83--------------------
84
85.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.c
86   :doc: frontbuffer tracking
87
88.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.h
89   :internal:
90
91.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.c
92   :internal:
93
94Display FIFO Underrun Reporting
95-------------------------------
96
97.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fifo_underrun.c
98   :doc: fifo underrun handling
99
100.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fifo_underrun.c
101   :internal:
102
103Plane Configuration
104-------------------
105
106This section covers plane configuration and composition with the primary
107plane, sprites, cursors and overlays. This includes the infrastructure
108to do atomic vsync'ed updates of all this state and also tightly coupled
109topics like watermark setup and computation, framebuffer compression and
110panel self refresh.
111
112Atomic Plane Helpers
113--------------------
114
115.. kernel-doc:: drivers/gpu/drm/i915/display/intel_atomic_plane.c
116   :doc: atomic plane helpers
117
118.. kernel-doc:: drivers/gpu/drm/i915/display/intel_atomic_plane.c
119   :internal:
120
121Asynchronous Page Flip
122----------------------
123
124.. kernel-doc:: drivers/gpu/drm/i915/display/intel_display.c
125   :doc: asynchronous flip implementation
126
127Output Probing
128--------------
129
130This section covers output probing and related infrastructure like the
131hotplug interrupt storm detection and mitigation code. Note that the
132i915 driver still uses most of the common DRM helper code for output
133probing, so those sections fully apply.
134
135Hotplug
136-------
137
138.. kernel-doc:: drivers/gpu/drm/i915/display/intel_hotplug.c
139   :doc: Hotplug
140
141.. kernel-doc:: drivers/gpu/drm/i915/display/intel_hotplug.c
142   :internal:
143
144High Definition Audio
145---------------------
146
147.. kernel-doc:: drivers/gpu/drm/i915/display/intel_audio.c
148   :doc: High Definition Audio over HDMI and Display Port
149
150.. kernel-doc:: drivers/gpu/drm/i915/display/intel_audio.c
151   :internal:
152
153.. kernel-doc:: include/drm/i915_component.h
154   :internal:
155
156Intel HDMI LPE Audio Support
157----------------------------
158
159.. kernel-doc:: drivers/gpu/drm/i915/display/intel_lpe_audio.c
160   :doc: LPE Audio integration for HDMI or DP playback
161
162.. kernel-doc:: drivers/gpu/drm/i915/display/intel_lpe_audio.c
163   :internal:
164
165Panel Self Refresh PSR (PSR/SRD)
166--------------------------------
167
168.. kernel-doc:: drivers/gpu/drm/i915/display/intel_psr.c
169   :doc: Panel Self Refresh (PSR/SRD)
170
171.. kernel-doc:: drivers/gpu/drm/i915/display/intel_psr.c
172   :internal:
173
174Frame Buffer Compression (FBC)
175------------------------------
176
177.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fbc.c
178   :doc: Frame Buffer Compression (FBC)
179
180.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fbc.c
181   :internal:
182
183Display Refresh Rate Switching (DRRS)
184-------------------------------------
185
186.. kernel-doc:: drivers/gpu/drm/i915/display/intel_drrs.c
187   :doc: Display Refresh Rate Switching (DRRS)
188
189.. kernel-doc:: drivers/gpu/drm/i915/display/intel_drrs.c
190   :internal:
191
192DPIO
193----
194
195.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpio_phy.c
196   :doc: DPIO
197
198DMC Firmware Support
199--------------------
200
201.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.c
202   :doc: DMC Firmware Support
203
204.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.c
205   :internal:
206
207Video BIOS Table (VBT)
208----------------------
209
210.. kernel-doc:: drivers/gpu/drm/i915/display/intel_bios.c
211   :doc: Video BIOS Table (VBT)
212
213.. kernel-doc:: drivers/gpu/drm/i915/display/intel_bios.c
214   :internal:
215
216.. kernel-doc:: drivers/gpu/drm/i915/display/intel_vbt_defs.h
217   :internal:
218
219Display clocks
220--------------
221
222.. kernel-doc:: drivers/gpu/drm/i915/display/intel_cdclk.c
223   :doc: CDCLK / RAWCLK
224
225.. kernel-doc:: drivers/gpu/drm/i915/display/intel_cdclk.c
226   :internal:
227
228Display PLLs
229------------
230
231.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.c
232   :doc: Display PLLs
233
234.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.c
235   :internal:
236
237.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.h
238   :internal:
239
240Display State Buffer
241--------------------
242
243.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c
244   :doc: DSB
245
246.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c
247   :internal:
248
249Memory Management and Command Submission
250========================================
251
252This sections covers all things related to the GEM implementation in the
253i915 driver.
254
255Intel GPU Basics
256----------------
257
258An Intel GPU has multiple engines. There are several engine types.
259
260- RCS engine is for rendering 3D and performing compute, this is named
261  `I915_EXEC_RENDER` in user space.
262- BCS is a blitting (copy) engine, this is named `I915_EXEC_BLT` in user
263  space.
264- VCS is a video encode and decode engine, this is named `I915_EXEC_BSD`
265  in user space
266- VECS is video enhancement engine, this is named `I915_EXEC_VEBOX` in user
267  space.
268- The enumeration `I915_EXEC_DEFAULT` does not refer to specific engine;
269  instead it is to be used by user space to specify a default rendering
270  engine (for 3D) that may or may not be the same as RCS.
271
272The Intel GPU family is a family of integrated GPU's using Unified
273Memory Access. For having the GPU "do work", user space will feed the
274GPU batch buffers via one of the ioctls `DRM_IOCTL_I915_GEM_EXECBUFFER2`
275or `DRM_IOCTL_I915_GEM_EXECBUFFER2_WR`. Most such batchbuffers will
276instruct the GPU to perform work (for example rendering) and that work
277needs memory from which to read and memory to which to write. All memory
278is encapsulated within GEM buffer objects (usually created with the ioctl
279`DRM_IOCTL_I915_GEM_CREATE`). An ioctl providing a batchbuffer for the GPU
280to create will also list all GEM buffer objects that the batchbuffer reads
281and/or writes. For implementation details of memory management see
282`GEM BO Management Implementation Details`_.
283
284The i915 driver allows user space to create a context via the ioctl
285`DRM_IOCTL_I915_GEM_CONTEXT_CREATE` which is identified by a 32-bit
286integer. Such a context should be viewed by user-space as -loosely-
287analogous to the idea of a CPU process of an operating system. The i915
288driver guarantees that commands issued to a fixed context are to be
289executed so that writes of a previously issued command are seen by
290reads of following commands. Actions issued between different contexts
291(even if from the same file descriptor) are NOT given that guarantee
292and the only way to synchronize across contexts (even from the same
293file descriptor) is through the use of fences. At least as far back as
294Gen4, also have that a context carries with it a GPU HW context;
295the HW context is essentially (most of atleast) the state of a GPU.
296In addition to the ordering guarantees, the kernel will restore GPU
297state via HW context when commands are issued to a context, this saves
298user space the need to restore (most of atleast) the GPU state at the
299start of each batchbuffer. The non-deprecated ioctls to submit batchbuffer
300work can pass that ID (in the lower bits of drm_i915_gem_execbuffer2::rsvd1)
301to identify what context to use with the command.
302
303The GPU has its own memory management and address space. The kernel
304driver maintains the memory translation table for the GPU. For older
305GPUs (i.e. those before Gen8), there is a single global such translation
306table, a global Graphics Translation Table (GTT). For newer generation
307GPUs each context has its own translation table, called Per-Process
308Graphics Translation Table (PPGTT). Of important note, is that although
309PPGTT is named per-process it is actually per context. When user space
310submits a batchbuffer, the kernel walks the list of GEM buffer objects
311used by the batchbuffer and guarantees that not only is the memory of
312each such GEM buffer object resident but it is also present in the
313(PP)GTT. If the GEM buffer object is not yet placed in the (PP)GTT,
314then it is given an address. Two consequences of this are: the kernel
315needs to edit the batchbuffer submitted to write the correct value of
316the GPU address when a GEM BO is assigned a GPU address and the kernel
317might evict a different GEM BO from the (PP)GTT to make address room
318for another GEM BO. Consequently, the ioctls submitting a batchbuffer
319for execution also include a list of all locations within buffers that
320refer to GPU-addresses so that the kernel can edit the buffer correctly.
321This process is dubbed relocation.
322
323Locking Guidelines
324------------------
325
326.. note::
327   This is a description of how the locking should be after
328   refactoring is done. Does not necessarily reflect what the locking
329   looks like while WIP.
330
331#. All locking rules and interface contracts with cross-driver interfaces
332   (dma-buf, dma_fence) need to be followed.
333
334#. No struct_mutex anywhere in the code
335
336#. dma_resv will be the outermost lock (when needed) and ww_acquire_ctx
337   is to be hoisted at highest level and passed down within i915_gem_ctx
338   in the call chain
339
340#. While holding lru/memory manager (buddy, drm_mm, whatever) locks
341   system memory allocations are not allowed
342
343	* Enforce this by priming lockdep (with fs_reclaim). If we
344	  allocate memory while holding these looks we get a rehash
345	  of the shrinker vs. struct_mutex saga, and that would be
346	  real bad.
347
348#. Do not nest different lru/memory manager locks within each other.
349   Take them in turn to update memory allocations, relying on the object’s
350   dma_resv ww_mutex to serialize against other operations.
351
352#. The suggestion for lru/memory managers locks is that they are small
353   enough to be spinlocks.
354
355#. All features need to come with exhaustive kernel selftests and/or
356   IGT tests when appropriate
357
358#. All LMEM uAPI paths need to be fully restartable (_interruptible()
359   for all locks/waits/sleeps)
360
361	* Error handling validation through signal injection.
362	  Still the best strategy we have for validating GEM uAPI
363          corner cases.
364	  Must be excessively used in the IGT, and we need to check
365	  that we really have full path coverage of all error cases.
366
367	* -EDEADLK handling with ww_mutex
368
369GEM BO Management Implementation Details
370----------------------------------------
371
372.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
373   :doc: Virtual Memory Address
374
375Buffer Object Eviction
376----------------------
377
378This section documents the interface functions for evicting buffer
379objects to make space available in the virtual gpu address spaces. Note
380that this is mostly orthogonal to shrinking buffer objects caches, which
381has the goal to make main memory (shared with the gpu through the
382unified memory architecture) available.
383
384.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_evict.c
385   :internal:
386
387Buffer Object Memory Shrinking
388------------------------------
389
390This section documents the interface function for shrinking memory usage
391of buffer object caches. Shrinking is used to make main memory
392available. Note that this is mostly orthogonal to evicting buffer
393objects, which has the goal to make space in gpu virtual address spaces.
394
395.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
396   :internal:
397
398Batchbuffer Parsing
399-------------------
400
401.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
402   :doc: batch buffer command parser
403
404.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
405   :internal:
406
407User Batchbuffer Execution
408--------------------------
409
410.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_context_types.h
411
412.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
413   :doc: User command execution
414
415Scheduling
416----------
417.. kernel-doc:: drivers/gpu/drm/i915/i915_scheduler_types.h
418   :functions: i915_sched_engine
419
420Logical Rings, Logical Ring Contexts and Execlists
421--------------------------------------------------
422
423.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_execlists_submission.c
424   :doc: Logical Rings, Logical Ring Contexts and Execlists
425
426Global GTT views
427----------------
428
429.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
430   :doc: Global GTT views
431
432.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c
433   :internal:
434
435GTT Fences and Swizzling
436------------------------
437
438.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
439   :internal:
440
441Global GTT Fence Handling
442~~~~~~~~~~~~~~~~~~~~~~~~~
443
444.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
445   :doc: fence register handling
446
447Hardware Tiling and Swizzling Details
448~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
449
450.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
451   :doc: tiling swizzling details
452
453Object Tiling IOCTLs
454--------------------
455
456.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c
457   :internal:
458
459.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c
460   :doc: buffer object tiling
461
462Protected Objects
463-----------------
464
465.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp.c
466   :doc: PXP
467
468.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp_types.h
469
470Microcontrollers
471================
472
473Starting from gen9, three microcontrollers are available on the HW: the
474graphics microcontroller (GuC), the HEVC/H.265 microcontroller (HuC) and the
475display microcontroller (DMC). The driver is responsible for loading the
476firmwares on the microcontrollers; the GuC and HuC firmwares are transferred
477to WOPCM using the DMA engine, while the DMC firmware is written through MMIO.
478
479WOPCM
480-----
481
482WOPCM Layout
483~~~~~~~~~~~~
484
485.. kernel-doc:: drivers/gpu/drm/i915/intel_wopcm.c
486   :doc: WOPCM Layout
487
488GuC
489---
490
491.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
492   :doc: GuC
493
494.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.h
495
496GuC Firmware Layout
497~~~~~~~~~~~~~~~~~~~
498
499.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h
500   :doc: Firmware Layout
501
502GuC Memory Management
503~~~~~~~~~~~~~~~~~~~~~
504
505.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
506   :doc: GuC Memory Management
507.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
508   :functions: intel_guc_allocate_vma
509
510
511GuC-specific firmware loader
512~~~~~~~~~~~~~~~~~~~~~~~~~~~~
513
514.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
515   :internal:
516
517GuC-based command submission
518~~~~~~~~~~~~~~~~~~~~~~~~~~~~
519
520.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
521   :doc: GuC-based command submission
522
523GuC ABI
524~~~~~~~~~~~~~~~~~~~~~~~~~~~~
525
526.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h
527.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h
528.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
529.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
530.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_klvs_abi.h
531
532HuC
533---
534.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
535   :doc: HuC
536.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
537   :functions: intel_huc_auth
538
539HuC Memory Management
540~~~~~~~~~~~~~~~~~~~~~
541
542.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
543   :doc: HuC Memory Management
544
545HuC Firmware Layout
546~~~~~~~~~~~~~~~~~~~
547The HuC FW layout is the same as the GuC one, see `GuC Firmware Layout`_
548
549DMC
550---
551See `DMC Firmware Support`_
552
553Tracing
554=======
555
556This sections covers all things related to the tracepoints implemented
557in the i915 driver.
558
559i915_ppgtt_create and i915_ppgtt_release
560----------------------------------------
561
562.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
563   :doc: i915_ppgtt_create and i915_ppgtt_release tracepoints
564
565i915_context_create and i915_context_free
566-----------------------------------------
567
568.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
569   :doc: i915_context_create and i915_context_free tracepoints
570
571Perf
572====
573
574Overview
575--------
576.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
577   :doc: i915 Perf Overview
578
579Comparison with Core Perf
580-------------------------
581.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
582   :doc: i915 Perf History and Comparison with Core Perf
583
584i915 Driver Entry Points
585------------------------
586
587This section covers the entrypoints exported outside of i915_perf.c to
588integrate with drm/i915 and to handle the `DRM_I915_PERF_OPEN` ioctl.
589
590.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
591   :functions: i915_perf_init
592.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
593   :functions: i915_perf_fini
594.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
595   :functions: i915_perf_register
596.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
597   :functions: i915_perf_unregister
598.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
599   :functions: i915_perf_open_ioctl
600.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
601   :functions: i915_perf_release
602.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
603   :functions: i915_perf_add_config_ioctl
604.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
605   :functions: i915_perf_remove_config_ioctl
606
607i915 Perf Stream
608----------------
609
610This section covers the stream-semantics-agnostic structures and functions
611for representing an i915 perf stream FD and associated file operations.
612
613.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
614   :functions: i915_perf_stream
615.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
616   :functions: i915_perf_stream_ops
617
618.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
619   :functions: read_properties_unlocked
620.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
621   :functions: i915_perf_open_ioctl_locked
622.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
623   :functions: i915_perf_destroy_locked
624.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
625   :functions: i915_perf_read
626.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
627   :functions: i915_perf_ioctl
628.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
629   :functions: i915_perf_enable_locked
630.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
631   :functions: i915_perf_disable_locked
632.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
633   :functions: i915_perf_poll
634.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
635   :functions: i915_perf_poll_locked
636
637i915 Perf Observation Architecture Stream
638-----------------------------------------
639
640.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
641   :functions: i915_oa_ops
642
643.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
644   :functions: i915_oa_stream_init
645.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
646   :functions: i915_oa_read
647.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
648   :functions: i915_oa_stream_enable
649.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
650   :functions: i915_oa_stream_disable
651.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
652   :functions: i915_oa_wait_unlocked
653.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
654   :functions: i915_oa_poll_wait
655
656Other i915 Perf Internals
657-------------------------
658
659This section simply includes all other currently documented i915 perf internals,
660in no particular order, but may include some more minor utilities or platform
661specific details than found in the more high-level sections.
662
663.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
664   :internal:
665   :no-identifiers:
666       i915_perf_init
667       i915_perf_fini
668       i915_perf_register
669       i915_perf_unregister
670       i915_perf_open_ioctl
671       i915_perf_release
672       i915_perf_add_config_ioctl
673       i915_perf_remove_config_ioctl
674       read_properties_unlocked
675       i915_perf_open_ioctl_locked
676       i915_perf_destroy_locked
677       i915_perf_read i915_perf_ioctl
678       i915_perf_enable_locked
679       i915_perf_disable_locked
680       i915_perf_poll i915_perf_poll_locked
681       i915_oa_stream_init i915_oa_read
682       i915_oa_stream_enable
683       i915_oa_stream_disable
684       i915_oa_wait_unlocked
685       i915_oa_poll_wait
686
687Style
688=====
689
690The drm/i915 driver codebase has some style rules in addition to (and, in some
691cases, deviating from) the kernel coding style.
692
693Register macro definition style
694-------------------------------
695
696The style guide for ``i915_reg.h``.
697
698.. kernel-doc:: drivers/gpu/drm/i915/i915_reg.h
699   :doc: The i915 register macro definition style guide
700
701.. _i915-usage-stats:
702
703i915 DRM client usage stats implementation
704==========================================
705
706The drm/i915 driver implements the DRM client usage stats specification as
707documented in :ref:`drm-client-usage-stats`.
708
709Example of the output showing the implemented key value pairs and entirety of
710the currently possible format options:
711
712::
713
714      pos:    0
715      flags:  0100002
716      mnt_id: 21
717      drm-driver: i915
718      drm-pdev:   0000:00:02.0
719      drm-client-id:      7
720      drm-engine-render:  9288864723 ns
721      drm-engine-copy:    2035071108 ns
722      drm-engine-video:   0 ns
723      drm-engine-capacity-video:   2
724      drm-engine-video-enhance:   0 ns
725
726Possible `drm-engine-` key names are: `render`, `copy`, `video` and
727`video-enhance`.
728