xref: /openbmc/linux/Documentation/gpu/i915.rst (revision e9b7b8b3)
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
249GT Programming
250==============
251
252Multicast/Replicated (MCR) Registers
253------------------------------------
254
255.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_mcr.c
256   :doc: GT Multicast/Replicated (MCR) Register Support
257
258.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_mcr.c
259   :internal:
260
261Memory Management and Command Submission
262========================================
263
264This sections covers all things related to the GEM implementation in the
265i915 driver.
266
267Intel GPU Basics
268----------------
269
270An Intel GPU has multiple engines. There are several engine types.
271
272- RCS engine is for rendering 3D and performing compute, this is named
273  `I915_EXEC_RENDER` in user space.
274- BCS is a blitting (copy) engine, this is named `I915_EXEC_BLT` in user
275  space.
276- VCS is a video encode and decode engine, this is named `I915_EXEC_BSD`
277  in user space
278- VECS is video enhancement engine, this is named `I915_EXEC_VEBOX` in user
279  space.
280- The enumeration `I915_EXEC_DEFAULT` does not refer to specific engine;
281  instead it is to be used by user space to specify a default rendering
282  engine (for 3D) that may or may not be the same as RCS.
283
284The Intel GPU family is a family of integrated GPU's using Unified
285Memory Access. For having the GPU "do work", user space will feed the
286GPU batch buffers via one of the ioctls `DRM_IOCTL_I915_GEM_EXECBUFFER2`
287or `DRM_IOCTL_I915_GEM_EXECBUFFER2_WR`. Most such batchbuffers will
288instruct the GPU to perform work (for example rendering) and that work
289needs memory from which to read and memory to which to write. All memory
290is encapsulated within GEM buffer objects (usually created with the ioctl
291`DRM_IOCTL_I915_GEM_CREATE`). An ioctl providing a batchbuffer for the GPU
292to create will also list all GEM buffer objects that the batchbuffer reads
293and/or writes. For implementation details of memory management see
294`GEM BO Management Implementation Details`_.
295
296The i915 driver allows user space to create a context via the ioctl
297`DRM_IOCTL_I915_GEM_CONTEXT_CREATE` which is identified by a 32-bit
298integer. Such a context should be viewed by user-space as -loosely-
299analogous to the idea of a CPU process of an operating system. The i915
300driver guarantees that commands issued to a fixed context are to be
301executed so that writes of a previously issued command are seen by
302reads of following commands. Actions issued between different contexts
303(even if from the same file descriptor) are NOT given that guarantee
304and the only way to synchronize across contexts (even from the same
305file descriptor) is through the use of fences. At least as far back as
306Gen4, also have that a context carries with it a GPU HW context;
307the HW context is essentially (most of at least) the state of a GPU.
308In addition to the ordering guarantees, the kernel will restore GPU
309state via HW context when commands are issued to a context, this saves
310user space the need to restore (most of at least) the GPU state at the
311start of each batchbuffer. The non-deprecated ioctls to submit batchbuffer
312work can pass that ID (in the lower bits of drm_i915_gem_execbuffer2::rsvd1)
313to identify what context to use with the command.
314
315The GPU has its own memory management and address space. The kernel
316driver maintains the memory translation table for the GPU. For older
317GPUs (i.e. those before Gen8), there is a single global such translation
318table, a global Graphics Translation Table (GTT). For newer generation
319GPUs each context has its own translation table, called Per-Process
320Graphics Translation Table (PPGTT). Of important note, is that although
321PPGTT is named per-process it is actually per context. When user space
322submits a batchbuffer, the kernel walks the list of GEM buffer objects
323used by the batchbuffer and guarantees that not only is the memory of
324each such GEM buffer object resident but it is also present in the
325(PP)GTT. If the GEM buffer object is not yet placed in the (PP)GTT,
326then it is given an address. Two consequences of this are: the kernel
327needs to edit the batchbuffer submitted to write the correct value of
328the GPU address when a GEM BO is assigned a GPU address and the kernel
329might evict a different GEM BO from the (PP)GTT to make address room
330for another GEM BO. Consequently, the ioctls submitting a batchbuffer
331for execution also include a list of all locations within buffers that
332refer to GPU-addresses so that the kernel can edit the buffer correctly.
333This process is dubbed relocation.
334
335Locking Guidelines
336------------------
337
338.. note::
339   This is a description of how the locking should be after
340   refactoring is done. Does not necessarily reflect what the locking
341   looks like while WIP.
342
343#. All locking rules and interface contracts with cross-driver interfaces
344   (dma-buf, dma_fence) need to be followed.
345
346#. No struct_mutex anywhere in the code
347
348#. dma_resv will be the outermost lock (when needed) and ww_acquire_ctx
349   is to be hoisted at highest level and passed down within i915_gem_ctx
350   in the call chain
351
352#. While holding lru/memory manager (buddy, drm_mm, whatever) locks
353   system memory allocations are not allowed
354
355	* Enforce this by priming lockdep (with fs_reclaim). If we
356	  allocate memory while holding these looks we get a rehash
357	  of the shrinker vs. struct_mutex saga, and that would be
358	  real bad.
359
360#. Do not nest different lru/memory manager locks within each other.
361   Take them in turn to update memory allocations, relying on the object’s
362   dma_resv ww_mutex to serialize against other operations.
363
364#. The suggestion for lru/memory managers locks is that they are small
365   enough to be spinlocks.
366
367#. All features need to come with exhaustive kernel selftests and/or
368   IGT tests when appropriate
369
370#. All LMEM uAPI paths need to be fully restartable (_interruptible()
371   for all locks/waits/sleeps)
372
373	* Error handling validation through signal injection.
374	  Still the best strategy we have for validating GEM uAPI
375          corner cases.
376	  Must be excessively used in the IGT, and we need to check
377	  that we really have full path coverage of all error cases.
378
379	* -EDEADLK handling with ww_mutex
380
381GEM BO Management Implementation Details
382----------------------------------------
383
384.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
385   :doc: Virtual Memory Address
386
387Buffer Object Eviction
388----------------------
389
390This section documents the interface functions for evicting buffer
391objects to make space available in the virtual gpu address spaces. Note
392that this is mostly orthogonal to shrinking buffer objects caches, which
393has the goal to make main memory (shared with the gpu through the
394unified memory architecture) available.
395
396.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_evict.c
397   :internal:
398
399Buffer Object Memory Shrinking
400------------------------------
401
402This section documents the interface function for shrinking memory usage
403of buffer object caches. Shrinking is used to make main memory
404available. Note that this is mostly orthogonal to evicting buffer
405objects, which has the goal to make space in gpu virtual address spaces.
406
407.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
408   :internal:
409
410Batchbuffer Parsing
411-------------------
412
413.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
414   :doc: batch buffer command parser
415
416.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c
417   :internal:
418
419User Batchbuffer Execution
420--------------------------
421
422.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_context_types.h
423
424.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
425   :doc: User command execution
426
427Scheduling
428----------
429.. kernel-doc:: drivers/gpu/drm/i915/i915_scheduler_types.h
430   :functions: i915_sched_engine
431
432Logical Rings, Logical Ring Contexts and Execlists
433--------------------------------------------------
434
435.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_execlists_submission.c
436   :doc: Logical Rings, Logical Ring Contexts and Execlists
437
438Global GTT views
439----------------
440
441.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h
442   :doc: Global GTT views
443
444.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c
445   :internal:
446
447GTT Fences and Swizzling
448------------------------
449
450.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
451   :internal:
452
453Global GTT Fence Handling
454~~~~~~~~~~~~~~~~~~~~~~~~~
455
456.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
457   :doc: fence register handling
458
459Hardware Tiling and Swizzling Details
460~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
461
462.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
463   :doc: tiling swizzling details
464
465Object Tiling IOCTLs
466--------------------
467
468.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c
469   :internal:
470
471.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c
472   :doc: buffer object tiling
473
474Protected Objects
475-----------------
476
477.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp.c
478   :doc: PXP
479
480.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp_types.h
481
482Microcontrollers
483================
484
485Starting from gen9, three microcontrollers are available on the HW: the
486graphics microcontroller (GuC), the HEVC/H.265 microcontroller (HuC) and the
487display microcontroller (DMC). The driver is responsible for loading the
488firmwares on the microcontrollers; the GuC and HuC firmwares are transferred
489to WOPCM using the DMA engine, while the DMC firmware is written through MMIO.
490
491WOPCM
492-----
493
494WOPCM Layout
495~~~~~~~~~~~~
496
497.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_wopcm.c
498   :doc: WOPCM Layout
499
500GuC
501---
502
503.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
504   :doc: GuC
505
506.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.h
507
508GuC Firmware Layout
509~~~~~~~~~~~~~~~~~~~
510
511.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h
512   :doc: Firmware Layout
513
514GuC Memory Management
515~~~~~~~~~~~~~~~~~~~~~
516
517.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
518   :doc: GuC Memory Management
519.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c
520   :functions: intel_guc_allocate_vma
521
522
523GuC-specific firmware loader
524~~~~~~~~~~~~~~~~~~~~~~~~~~~~
525
526.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c
527   :internal:
528
529GuC-based command submission
530~~~~~~~~~~~~~~~~~~~~~~~~~~~~
531
532.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
533   :doc: GuC-based command submission
534
535GuC ABI
536~~~~~~~~~~~~~~~~~~~~~~~~~~~~
537
538.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h
539.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h
540.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
541.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
542.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_klvs_abi.h
543
544HuC
545---
546.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
547   :doc: HuC
548.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
549   :functions: intel_huc_auth
550
551HuC Memory Management
552~~~~~~~~~~~~~~~~~~~~~
553
554.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c
555   :doc: HuC Memory Management
556
557HuC Firmware Layout
558~~~~~~~~~~~~~~~~~~~
559The HuC FW layout is the same as the GuC one, see `GuC Firmware Layout`_
560
561DMC
562---
563See `DMC Firmware Support`_
564
565Tracing
566=======
567
568This sections covers all things related to the tracepoints implemented
569in the i915 driver.
570
571i915_ppgtt_create and i915_ppgtt_release
572----------------------------------------
573
574.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
575   :doc: i915_ppgtt_create and i915_ppgtt_release tracepoints
576
577i915_context_create and i915_context_free
578-----------------------------------------
579
580.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
581   :doc: i915_context_create and i915_context_free tracepoints
582
583Perf
584====
585
586Overview
587--------
588.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
589   :doc: i915 Perf Overview
590
591Comparison with Core Perf
592-------------------------
593.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
594   :doc: i915 Perf History and Comparison with Core Perf
595
596i915 Driver Entry Points
597------------------------
598
599This section covers the entrypoints exported outside of i915_perf.c to
600integrate with drm/i915 and to handle the `DRM_I915_PERF_OPEN` ioctl.
601
602.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
603   :functions: i915_perf_init
604.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
605   :functions: i915_perf_fini
606.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
607   :functions: i915_perf_register
608.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
609   :functions: i915_perf_unregister
610.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
611   :functions: i915_perf_open_ioctl
612.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
613   :functions: i915_perf_release
614.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
615   :functions: i915_perf_add_config_ioctl
616.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
617   :functions: i915_perf_remove_config_ioctl
618
619i915 Perf Stream
620----------------
621
622This section covers the stream-semantics-agnostic structures and functions
623for representing an i915 perf stream FD and associated file operations.
624
625.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
626   :functions: i915_perf_stream
627.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
628   :functions: i915_perf_stream_ops
629
630.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
631   :functions: read_properties_unlocked
632.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
633   :functions: i915_perf_open_ioctl_locked
634.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
635   :functions: i915_perf_destroy_locked
636.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
637   :functions: i915_perf_read
638.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
639   :functions: i915_perf_ioctl
640.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
641   :functions: i915_perf_enable_locked
642.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
643   :functions: i915_perf_disable_locked
644.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
645   :functions: i915_perf_poll
646.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
647   :functions: i915_perf_poll_locked
648
649i915 Perf Observation Architecture Stream
650-----------------------------------------
651
652.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h
653   :functions: i915_oa_ops
654
655.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
656   :functions: i915_oa_stream_init
657.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
658   :functions: i915_oa_read
659.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
660   :functions: i915_oa_stream_enable
661.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
662   :functions: i915_oa_stream_disable
663.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
664   :functions: i915_oa_wait_unlocked
665.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
666   :functions: i915_oa_poll_wait
667
668Other i915 Perf Internals
669-------------------------
670
671This section simply includes all other currently documented i915 perf internals,
672in no particular order, but may include some more minor utilities or platform
673specific details than found in the more high-level sections.
674
675.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
676   :internal:
677   :no-identifiers:
678       i915_perf_init
679       i915_perf_fini
680       i915_perf_register
681       i915_perf_unregister
682       i915_perf_open_ioctl
683       i915_perf_release
684       i915_perf_add_config_ioctl
685       i915_perf_remove_config_ioctl
686       read_properties_unlocked
687       i915_perf_open_ioctl_locked
688       i915_perf_destroy_locked
689       i915_perf_read i915_perf_ioctl
690       i915_perf_enable_locked
691       i915_perf_disable_locked
692       i915_perf_poll i915_perf_poll_locked
693       i915_oa_stream_init i915_oa_read
694       i915_oa_stream_enable
695       i915_oa_stream_disable
696       i915_oa_wait_unlocked
697       i915_oa_poll_wait
698
699Style
700=====
701
702The drm/i915 driver codebase has some style rules in addition to (and, in some
703cases, deviating from) the kernel coding style.
704
705Register macro definition style
706-------------------------------
707
708The style guide for ``i915_reg.h``.
709
710.. kernel-doc:: drivers/gpu/drm/i915/i915_reg.h
711   :doc: The i915 register macro definition style guide
712
713.. _i915-usage-stats:
714
715i915 DRM client usage stats implementation
716==========================================
717
718The drm/i915 driver implements the DRM client usage stats specification as
719documented in :ref:`drm-client-usage-stats`.
720
721Example of the output showing the implemented key value pairs and entirety of
722the currently possible format options:
723
724::
725
726      pos:    0
727      flags:  0100002
728      mnt_id: 21
729      drm-driver: i915
730      drm-pdev:   0000:00:02.0
731      drm-client-id:      7
732      drm-engine-render:  9288864723 ns
733      drm-engine-copy:    2035071108 ns
734      drm-engine-video:   0 ns
735      drm-engine-capacity-video:   2
736      drm-engine-video-enhance:   0 ns
737
738Possible `drm-engine-` key names are: `render`, `copy`, `video` and
739`video-enhance`.
740