1 ========================= 1 =========================
2 Kernel Mode Setting (KMS) 2 Kernel Mode Setting (KMS)
3 ========================= 3 =========================
4 4
5 Drivers must initialize the mode setting core 5 Drivers must initialize the mode setting core by calling
6 drmm_mode_config_init() on the DRM device. The !! 6 :c:func:`drm_mode_config_init()` on the DRM device. The function
7 initializes the :c:type:`struct drm_device <dr 7 initializes the :c:type:`struct drm_device <drm_device>`
8 mode_config field and never fails. Once done, 8 mode_config field and never fails. Once done, mode configuration must
9 be setup by initializing the following fields. 9 be setup by initializing the following fields.
10 10
11 - int min_width, min_height; int max_width, m 11 - int min_width, min_height; int max_width, max_height;
12 Minimum and maximum width and height of the 12 Minimum and maximum width and height of the frame buffers in pixel
13 units. 13 units.
14 14
15 - struct drm_mode_config_funcs \*funcs; 15 - struct drm_mode_config_funcs \*funcs;
16 Mode setting functions. 16 Mode setting functions.
17 17
18 Overview 18 Overview
19 ======== 19 ========
20 20
21 .. kernel-render:: DOT 21 .. kernel-render:: DOT
22 :alt: KMS Display Pipeline 22 :alt: KMS Display Pipeline
23 :caption: KMS Display Pipeline Overview 23 :caption: KMS Display Pipeline Overview
24 24
25 digraph "KMS" { 25 digraph "KMS" {
26 node [shape=box] 26 node [shape=box]
27 27
28 subgraph cluster_static { 28 subgraph cluster_static {
29 style=dashed 29 style=dashed
30 label="Static Objects" 30 label="Static Objects"
31 31
32 node [bgcolor=grey style=filled] 32 node [bgcolor=grey style=filled]
33 "drm_plane A" -> "drm_crtc" 33 "drm_plane A" -> "drm_crtc"
34 "drm_plane B" -> "drm_crtc" 34 "drm_plane B" -> "drm_crtc"
35 "drm_crtc" -> "drm_encoder A" 35 "drm_crtc" -> "drm_encoder A"
36 "drm_crtc" -> "drm_encoder B" 36 "drm_crtc" -> "drm_encoder B"
37 } 37 }
38 38
39 subgraph cluster_user_created { 39 subgraph cluster_user_created {
40 style=dashed 40 style=dashed
41 label="Userspace-Created" 41 label="Userspace-Created"
42 42
43 node [shape=oval] 43 node [shape=oval]
44 "drm_framebuffer 1" -> "drm_plane A" 44 "drm_framebuffer 1" -> "drm_plane A"
45 "drm_framebuffer 2" -> "drm_plane B" 45 "drm_framebuffer 2" -> "drm_plane B"
46 } 46 }
47 47
48 subgraph cluster_connector { 48 subgraph cluster_connector {
49 style=dashed 49 style=dashed
50 label="Hotpluggable" 50 label="Hotpluggable"
51 51
52 "drm_encoder A" -> "drm_connector A" 52 "drm_encoder A" -> "drm_connector A"
53 "drm_encoder B" -> "drm_connector B" 53 "drm_encoder B" -> "drm_connector B"
54 } 54 }
55 } 55 }
56 56
57 The basic object structure KMS presents to use 57 The basic object structure KMS presents to userspace is fairly simple.
58 Framebuffers (represented by :c:type:`struct d 58 Framebuffers (represented by :c:type:`struct drm_framebuffer <drm_framebuffer>`,
59 see `Frame Buffer Abstraction`_) feed into pla !! 59 see `Frame Buffer Abstraction`_) feed into planes. One or more (or even no)
60 :c:type:`struct drm_plane <drm_plane>`, see `P !! 60 planes feed their pixel data into a CRTC (represented by :c:type:`struct
61 details. One or more (or even no) planes feed !! 61 drm_crtc <drm_crtc>`, see `CRTC Abstraction`_) for blending. The precise
62 (represented by :c:type:`struct drm_crtc <drm_ !! 62 blending step is explained in more detail in `Plane Composition Properties`_ and
63 for blending. The precise blending step is exp !! 63 related chapters.
64 Composition Properties`_ and related chapters. <<
65 64
66 For the output routing the first step is encod 65 For the output routing the first step is encoders (represented by
67 :c:type:`struct drm_encoder <drm_encoder>`, se 66 :c:type:`struct drm_encoder <drm_encoder>`, see `Encoder Abstraction`_). Those
68 are really just internal artifacts of the help 67 are really just internal artifacts of the helper libraries used to implement KMS
69 drivers. Besides that they make it unnecessari !! 68 drivers. Besides that they make it unecessarily more complicated for userspace
70 to figure out which connections between a CRTC 69 to figure out which connections between a CRTC and a connector are possible, and
71 what kind of cloning is supported, they serve 70 what kind of cloning is supported, they serve no purpose in the userspace API.
72 Unfortunately encoders have been exposed to us 71 Unfortunately encoders have been exposed to userspace, hence can't remove them
73 at this point. Furthermore the exposed restri !! 72 at this point. Futhermore the exposed restrictions are often wrongly set by
74 drivers, and in many cases not powerful enough 73 drivers, and in many cases not powerful enough to express the real restrictions.
75 A CRTC can be connected to multiple encoders, 74 A CRTC can be connected to multiple encoders, and for an active CRTC there must
76 be at least one encoder. 75 be at least one encoder.
77 76
78 The final, and real, endpoint in the display c 77 The final, and real, endpoint in the display chain is the connector (represented
79 by :c:type:`struct drm_connector <drm_connecto 78 by :c:type:`struct drm_connector <drm_connector>`, see `Connector
80 Abstraction`_). Connectors can have different 79 Abstraction`_). Connectors can have different possible encoders, but the kernel
81 driver selects which encoder to use for each c 80 driver selects which encoder to use for each connector. The use case is DVI,
82 which could switch between an analog and a dig 81 which could switch between an analog and a digital encoder. Encoders can also
83 drive multiple different connectors. There is 82 drive multiple different connectors. There is exactly one active connector for
84 every active encoder. 83 every active encoder.
85 84
86 Internally the output pipeline is a bit more c 85 Internally the output pipeline is a bit more complex and matches today's
87 hardware more closely: 86 hardware more closely:
88 87
89 .. kernel-render:: DOT 88 .. kernel-render:: DOT
90 :alt: KMS Output Pipeline 89 :alt: KMS Output Pipeline
91 :caption: KMS Output Pipeline 90 :caption: KMS Output Pipeline
92 91
93 digraph "Output Pipeline" { 92 digraph "Output Pipeline" {
94 node [shape=box] 93 node [shape=box]
95 94
96 subgraph { 95 subgraph {
97 "drm_crtc" [bgcolor=grey style=fille 96 "drm_crtc" [bgcolor=grey style=filled]
98 } 97 }
99 98
100 subgraph cluster_internal { 99 subgraph cluster_internal {
101 style=dashed 100 style=dashed
102 label="Internal Pipeline" 101 label="Internal Pipeline"
103 { 102 {
104 node [bgcolor=grey style=filled] 103 node [bgcolor=grey style=filled]
105 "drm_encoder A"; 104 "drm_encoder A";
106 "drm_encoder B"; 105 "drm_encoder B";
107 "drm_encoder C"; 106 "drm_encoder C";
108 } 107 }
109 108
110 { 109 {
111 node [bgcolor=grey style=filled] 110 node [bgcolor=grey style=filled]
112 "drm_encoder B" -> "drm_bridge B 111 "drm_encoder B" -> "drm_bridge B"
113 "drm_encoder C" -> "drm_bridge C 112 "drm_encoder C" -> "drm_bridge C1"
114 "drm_bridge C1" -> "drm_bridge C 113 "drm_bridge C1" -> "drm_bridge C2";
115 } 114 }
116 } 115 }
117 116
118 "drm_crtc" -> "drm_encoder A" 117 "drm_crtc" -> "drm_encoder A"
119 "drm_crtc" -> "drm_encoder B" 118 "drm_crtc" -> "drm_encoder B"
120 "drm_crtc" -> "drm_encoder C" 119 "drm_crtc" -> "drm_encoder C"
121 120
122 121
123 subgraph cluster_output { 122 subgraph cluster_output {
124 style=dashed 123 style=dashed
125 label="Outputs" 124 label="Outputs"
126 125
127 "drm_encoder A" -> "drm_connector A" 126 "drm_encoder A" -> "drm_connector A";
128 "drm_bridge B" -> "drm_connector B"; 127 "drm_bridge B" -> "drm_connector B";
129 "drm_bridge C2" -> "drm_connector C" 128 "drm_bridge C2" -> "drm_connector C";
130 129
131 "drm_panel" 130 "drm_panel"
132 } 131 }
133 } 132 }
134 133
135 Internally two additional helper objects come 134 Internally two additional helper objects come into play. First, to be able to
136 share code for encoders (sometimes on the same 135 share code for encoders (sometimes on the same SoC, sometimes off-chip) one or
137 more :ref:`drm_bridges` (represented by :c:typ 136 more :ref:`drm_bridges` (represented by :c:type:`struct drm_bridge
138 <drm_bridge>`) can be linked to an encoder. Th 137 <drm_bridge>`) can be linked to an encoder. This link is static and cannot be
139 changed, which means the cross-bar (if there i 138 changed, which means the cross-bar (if there is any) needs to be mapped between
140 the CRTC and any encoders. Often for drivers w 139 the CRTC and any encoders. Often for drivers with bridges there's no code left
141 at the encoder level. Atomic drivers can leave 140 at the encoder level. Atomic drivers can leave out all the encoder callbacks to
142 essentially only leave a dummy routing object 141 essentially only leave a dummy routing object behind, which is needed for
143 backwards compatibility since encoders are exp 142 backwards compatibility since encoders are exposed to userspace.
144 143
145 The second object is for panels, represented b 144 The second object is for panels, represented by :c:type:`struct drm_panel
146 <drm_panel>`, see :ref:`drm_panel_helper`. Pan 145 <drm_panel>`, see :ref:`drm_panel_helper`. Panels do not have a fixed binding
147 point, but are generally linked to the driver 146 point, but are generally linked to the driver private structure that embeds
148 :c:type:`struct drm_connector <drm_connector>` 147 :c:type:`struct drm_connector <drm_connector>`.
149 148
150 Note that currently the bridge chaining and in 149 Note that currently the bridge chaining and interactions with connectors and
151 panels are still in-flux and not really fully 150 panels are still in-flux and not really fully sorted out yet.
152 151
153 KMS Core Structures and Functions 152 KMS Core Structures and Functions
154 ================================= 153 =================================
155 154
156 .. kernel-doc:: include/drm/drm_mode_config.h 155 .. kernel-doc:: include/drm/drm_mode_config.h
157 :internal: 156 :internal:
158 157
159 .. kernel-doc:: drivers/gpu/drm/drm_mode_confi 158 .. kernel-doc:: drivers/gpu/drm/drm_mode_config.c
160 :export: 159 :export:
161 160
162 .. _kms_base_object_abstraction: <<
163 <<
164 Modeset Base Object Abstraction 161 Modeset Base Object Abstraction
165 =============================== 162 ===============================
166 163
167 .. kernel-render:: DOT 164 .. kernel-render:: DOT
168 :alt: Mode Objects and Properties 165 :alt: Mode Objects and Properties
169 :caption: Mode Objects and Properties 166 :caption: Mode Objects and Properties
170 167
171 digraph { 168 digraph {
172 node [shape=box] 169 node [shape=box]
173 170
174 "drm_property A" -> "drm_mode_object A" 171 "drm_property A" -> "drm_mode_object A"
175 "drm_property A" -> "drm_mode_object B" 172 "drm_property A" -> "drm_mode_object B"
176 "drm_property B" -> "drm_mode_object A" 173 "drm_property B" -> "drm_mode_object A"
177 } 174 }
178 175
179 The base structure for all KMS objects is :c:t 176 The base structure for all KMS objects is :c:type:`struct drm_mode_object
180 <drm_mode_object>`. One of the base services i 177 <drm_mode_object>`. One of the base services it provides is tracking properties,
181 which are especially important for the atomic 178 which are especially important for the atomic IOCTL (see `Atomic Mode
182 Setting`_). The somewhat surprising part here 179 Setting`_). The somewhat surprising part here is that properties are not
183 directly instantiated on each object, but free 180 directly instantiated on each object, but free-standing mode objects themselves,
184 represented by :c:type:`struct drm_property <d 181 represented by :c:type:`struct drm_property <drm_property>`, which only specify
185 the type and value range of a property. Any gi 182 the type and value range of a property. Any given property can be attached
186 multiple times to different objects using drm_ !! 183 multiple times to different objects using :c:func:`drm_object_attach_property()
>> 184 <drm_object_attach_property>`.
187 185
188 .. kernel-doc:: include/drm/drm_mode_object.h 186 .. kernel-doc:: include/drm/drm_mode_object.h
189 :internal: 187 :internal:
190 188
191 .. kernel-doc:: drivers/gpu/drm/drm_mode_objec 189 .. kernel-doc:: drivers/gpu/drm/drm_mode_object.c
192 :export: 190 :export:
193 191
194 Atomic Mode Setting 192 Atomic Mode Setting
195 =================== 193 ===================
196 194
197 195
198 .. kernel-render:: DOT 196 .. kernel-render:: DOT
199 :alt: Mode Objects and Properties 197 :alt: Mode Objects and Properties
200 :caption: Mode Objects and Properties 198 :caption: Mode Objects and Properties
201 199
202 digraph { 200 digraph {
203 node [shape=box] 201 node [shape=box]
204 202
205 subgraph cluster_state { 203 subgraph cluster_state {
206 style=dashed 204 style=dashed
207 label="Free-standing state" 205 label="Free-standing state"
208 206
209 "drm_atomic_state" -> "duplicated dr 207 "drm_atomic_state" -> "duplicated drm_plane_state A"
210 "drm_atomic_state" -> "duplicated dr 208 "drm_atomic_state" -> "duplicated drm_plane_state B"
211 "drm_atomic_state" -> "duplicated dr 209 "drm_atomic_state" -> "duplicated drm_crtc_state"
212 "drm_atomic_state" -> "duplicated dr 210 "drm_atomic_state" -> "duplicated drm_connector_state"
213 "drm_atomic_state" -> "duplicated dr 211 "drm_atomic_state" -> "duplicated driver private state"
214 } 212 }
215 213
216 subgraph cluster_current { 214 subgraph cluster_current {
217 style=dashed 215 style=dashed
218 label="Current state" 216 label="Current state"
219 217
220 "drm_device" -> "drm_plane A" 218 "drm_device" -> "drm_plane A"
221 "drm_device" -> "drm_plane B" 219 "drm_device" -> "drm_plane B"
222 "drm_device" -> "drm_crtc" 220 "drm_device" -> "drm_crtc"
223 "drm_device" -> "drm_connector" 221 "drm_device" -> "drm_connector"
224 "drm_device" -> "driver private obje 222 "drm_device" -> "driver private object"
225 223
226 "drm_plane A" -> "drm_plane_state A" 224 "drm_plane A" -> "drm_plane_state A"
227 "drm_plane B" -> "drm_plane_state B" 225 "drm_plane B" -> "drm_plane_state B"
228 "drm_crtc" -> "drm_crtc_state" 226 "drm_crtc" -> "drm_crtc_state"
229 "drm_connector" -> "drm_connector_st 227 "drm_connector" -> "drm_connector_state"
230 "driver private object" -> "driver p 228 "driver private object" -> "driver private state"
231 } 229 }
232 230
233 "drm_atomic_state" -> "drm_device" [labe 231 "drm_atomic_state" -> "drm_device" [label="atomic_commit"]
234 "duplicated drm_plane_state A" -> "drm_d 232 "duplicated drm_plane_state A" -> "drm_device"[style=invis]
235 } 233 }
236 234
237 Atomic provides transactional modeset (includi 235 Atomic provides transactional modeset (including planes) updates, but a
238 bit differently from the usual transactional a 236 bit differently from the usual transactional approach of try-commit and
239 rollback: 237 rollback:
240 238
241 - Firstly, no hardware changes are allowed whe 239 - Firstly, no hardware changes are allowed when the commit would fail. This
242 allows us to implement the DRM_MODE_ATOMIC_T 240 allows us to implement the DRM_MODE_ATOMIC_TEST_ONLY mode, which allows
243 userspace to explore whether certain configu 241 userspace to explore whether certain configurations would work or not.
244 242
245 - This would still allow setting and rollback 243 - This would still allow setting and rollback of just the software state,
246 simplifying conversion of existing drivers. 244 simplifying conversion of existing drivers. But auditing drivers for
247 correctness of the atomic_check code becomes 245 correctness of the atomic_check code becomes really hard with that: Rolling
248 back changes in data structures all over the 246 back changes in data structures all over the place is hard to get right.
249 247
250 - Lastly, for backwards compatibility and to s 248 - Lastly, for backwards compatibility and to support all use-cases, atomic
251 updates need to be incremental and be able t 249 updates need to be incremental and be able to execute in parallel. Hardware
252 doesn't always allow it, but where possible 250 doesn't always allow it, but where possible plane updates on different CRTCs
253 should not interfere, and not get stalled du 251 should not interfere, and not get stalled due to output routing changing on
254 different CRTCs. 252 different CRTCs.
255 253
256 Taken all together there's two consequences fo 254 Taken all together there's two consequences for the atomic design:
257 255
258 - The overall state is split up into per-objec 256 - The overall state is split up into per-object state structures:
259 :c:type:`struct drm_plane_state <drm_plane_s 257 :c:type:`struct drm_plane_state <drm_plane_state>` for planes, :c:type:`struct
260 drm_crtc_state <drm_crtc_state>` for CRTCs a 258 drm_crtc_state <drm_crtc_state>` for CRTCs and :c:type:`struct
261 drm_connector_state <drm_connector_state>` f 259 drm_connector_state <drm_connector_state>` for connectors. These are the only
262 objects with userspace-visible and settable 260 objects with userspace-visible and settable state. For internal state drivers
263 can subclass these structures through embedd !! 261 can subclass these structures through embeddeding, or add entirely new state
264 structures for their globally shared hardwar !! 262 structures for their globally shared hardware functions.
265 drm_private_state<drm_private_state>`. <<
266 263
267 - An atomic update is assembled and validated 264 - An atomic update is assembled and validated as an entirely free-standing pile
268 of structures within the :c:type:`drm_atomic 265 of structures within the :c:type:`drm_atomic_state <drm_atomic_state>`
269 container. Driver private state structures a 266 container. Driver private state structures are also tracked in the same
270 structure; see the next chapter. Only when 267 structure; see the next chapter. Only when a state is committed is it applied
271 to the driver and modeset objects. This way 268 to the driver and modeset objects. This way rolling back an update boils down
272 to releasing memory and unreferencing object 269 to releasing memory and unreferencing objects like framebuffers.
273 270
274 Locking of atomic state structures is internal <<
275 drm_modeset_lock <drm_modeset_lock>`. As a gen <<
276 exposed to drivers, instead the right locks sh <<
277 any function that duplicates or peeks into a s <<
278 drm_atomic_get_crtc_state(). Locking only pro <<
279 structure, ordering of committing state change <<
280 :c:type:`struct drm_crtc_commit <drm_crtc_comm <<
281 <<
282 Read on in this chapter, and also in :ref:`drm 271 Read on in this chapter, and also in :ref:`drm_atomic_helper` for more detailed
283 coverage of specific topics. 272 coverage of specific topics.
284 273
285 Handling Driver Private State 274 Handling Driver Private State
286 ----------------------------- 275 -----------------------------
287 276
288 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c 277 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c
289 :doc: handling driver private state 278 :doc: handling driver private state
290 279
291 Atomic Mode Setting Function Reference 280 Atomic Mode Setting Function Reference
292 -------------------------------------- 281 --------------------------------------
293 282
294 .. kernel-doc:: include/drm/drm_atomic.h 283 .. kernel-doc:: include/drm/drm_atomic.h
295 :internal: 284 :internal:
296 285
297 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c 286 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c
298 :export: 287 :export:
299 288
300 Atomic Mode Setting IOCTL and UAPI Functions !! 289 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c
301 -------------------------------------------- !! 290 :internal:
302 <<
303 .. kernel-doc:: drivers/gpu/drm/drm_atomic_uap <<
304 :doc: overview <<
305 <<
306 .. kernel-doc:: drivers/gpu/drm/drm_atomic_uap <<
307 :export: <<
308 291
309 CRTC Abstraction 292 CRTC Abstraction
310 ================ 293 ================
311 294
312 .. kernel-doc:: drivers/gpu/drm/drm_crtc.c 295 .. kernel-doc:: drivers/gpu/drm/drm_crtc.c
313 :doc: overview 296 :doc: overview
314 297
315 CRTC Functions Reference 298 CRTC Functions Reference
316 -------------------------------- 299 --------------------------------
317 300
318 .. kernel-doc:: include/drm/drm_crtc.h 301 .. kernel-doc:: include/drm/drm_crtc.h
319 :internal: 302 :internal:
320 303
321 .. kernel-doc:: drivers/gpu/drm/drm_crtc.c 304 .. kernel-doc:: drivers/gpu/drm/drm_crtc.c
322 :export: 305 :export:
323 306
324 Color Management Functions Reference <<
325 ------------------------------------ <<
326 <<
327 .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt <<
328 :export: <<
329 <<
330 .. kernel-doc:: include/drm/drm_color_mgmt.h <<
331 :internal: <<
332 <<
333 Frame Buffer Abstraction 307 Frame Buffer Abstraction
334 ======================== 308 ========================
335 309
336 .. kernel-doc:: drivers/gpu/drm/drm_framebuffe 310 .. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c
337 :doc: overview 311 :doc: overview
338 312
339 Frame Buffer Functions Reference 313 Frame Buffer Functions Reference
340 -------------------------------- 314 --------------------------------
341 315
342 .. kernel-doc:: include/drm/drm_framebuffer.h 316 .. kernel-doc:: include/drm/drm_framebuffer.h
343 :internal: 317 :internal:
344 318
345 .. kernel-doc:: drivers/gpu/drm/drm_framebuffe 319 .. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c
346 :export: 320 :export:
347 321
348 DRM Format Handling 322 DRM Format Handling
349 =================== 323 ===================
350 324
351 .. kernel-doc:: include/uapi/drm/drm_fourcc.h <<
352 :doc: overview <<
353 <<
354 Format Functions Reference <<
355 -------------------------- <<
356 <<
357 .. kernel-doc:: include/drm/drm_fourcc.h 325 .. kernel-doc:: include/drm/drm_fourcc.h
358 :internal: 326 :internal:
359 327
360 .. kernel-doc:: drivers/gpu/drm/drm_fourcc.c 328 .. kernel-doc:: drivers/gpu/drm/drm_fourcc.c
361 :export: 329 :export:
362 330
363 .. _kms_dumb_buffer_objects: <<
364 <<
365 Dumb Buffer Objects 331 Dumb Buffer Objects
366 =================== 332 ===================
367 333
368 .. kernel-doc:: drivers/gpu/drm/drm_dumb_buffe 334 .. kernel-doc:: drivers/gpu/drm/drm_dumb_buffers.c
369 :doc: overview 335 :doc: overview
370 336
371 Plane Abstraction 337 Plane Abstraction
372 ================= 338 =================
373 339
374 .. kernel-doc:: drivers/gpu/drm/drm_plane.c 340 .. kernel-doc:: drivers/gpu/drm/drm_plane.c
375 :doc: overview 341 :doc: overview
376 342
377 Plane Functions Reference 343 Plane Functions Reference
378 ------------------------- 344 -------------------------
379 345
380 .. kernel-doc:: include/drm/drm_plane.h 346 .. kernel-doc:: include/drm/drm_plane.h
381 :internal: 347 :internal:
382 348
383 .. kernel-doc:: drivers/gpu/drm/drm_plane.c 349 .. kernel-doc:: drivers/gpu/drm/drm_plane.c
384 :export: 350 :export:
385 351
386 Plane Composition Functions Reference <<
387 ------------------------------------- <<
388 <<
389 .. kernel-doc:: drivers/gpu/drm/drm_blend.c <<
390 :export: <<
391 <<
392 Plane Damage Tracking Functions Reference <<
393 ----------------------------------------- <<
394 <<
395 .. kernel-doc:: drivers/gpu/drm/drm_damage_hel <<
396 :export: <<
397 <<
398 .. kernel-doc:: include/drm/drm_damage_helper. <<
399 :internal: <<
400 <<
401 Plane Panic Feature <<
402 ------------------- <<
403 <<
404 .. kernel-doc:: drivers/gpu/drm/drm_panic.c <<
405 :doc: overview <<
406 <<
407 Plane Panic Functions Reference <<
408 ------------------------------- <<
409 <<
410 .. kernel-doc:: include/drm/drm_panic.h <<
411 :internal: <<
412 <<
413 .. kernel-doc:: drivers/gpu/drm/drm_panic.c <<
414 :export: <<
415 <<
416 Display Modes Function Reference 352 Display Modes Function Reference
417 ================================ 353 ================================
418 354
419 .. kernel-doc:: include/drm/drm_modes.h 355 .. kernel-doc:: include/drm/drm_modes.h
420 :internal: 356 :internal:
421 357
422 .. kernel-doc:: drivers/gpu/drm/drm_modes.c 358 .. kernel-doc:: drivers/gpu/drm/drm_modes.c
423 :export: 359 :export:
424 360
425 Connector Abstraction 361 Connector Abstraction
426 ===================== 362 =====================
427 363
428 .. kernel-doc:: drivers/gpu/drm/drm_connector. 364 .. kernel-doc:: drivers/gpu/drm/drm_connector.c
429 :doc: overview 365 :doc: overview
430 366
431 Connector Functions Reference 367 Connector Functions Reference
432 ----------------------------- 368 -----------------------------
433 369
434 .. kernel-doc:: include/drm/drm_connector.h 370 .. kernel-doc:: include/drm/drm_connector.h
435 :internal: 371 :internal:
436 372
437 .. kernel-doc:: drivers/gpu/drm/drm_connector. 373 .. kernel-doc:: drivers/gpu/drm/drm_connector.c
438 :export: 374 :export:
439 375
440 Writeback Connectors <<
441 -------------------- <<
442 <<
443 .. kernel-doc:: drivers/gpu/drm/drm_writeback. <<
444 :doc: overview <<
445 <<
446 .. kernel-doc:: include/drm/drm_writeback.h <<
447 :internal: <<
448 <<
449 .. kernel-doc:: drivers/gpu/drm/drm_writeback. <<
450 :export: <<
451 <<
452 Encoder Abstraction 376 Encoder Abstraction
453 =================== 377 ===================
454 378
455 .. kernel-doc:: drivers/gpu/drm/drm_encoder.c 379 .. kernel-doc:: drivers/gpu/drm/drm_encoder.c
456 :doc: overview 380 :doc: overview
457 381
458 Encoder Functions Reference 382 Encoder Functions Reference
459 --------------------------- 383 ---------------------------
460 384
461 .. kernel-doc:: include/drm/drm_encoder.h 385 .. kernel-doc:: include/drm/drm_encoder.h
462 :internal: 386 :internal:
463 387
464 .. kernel-doc:: drivers/gpu/drm/drm_encoder.c 388 .. kernel-doc:: drivers/gpu/drm/drm_encoder.c
465 :export: 389 :export:
466 390
>> 391 KMS Initialization and Cleanup
>> 392 ==============================
>> 393
>> 394 A KMS device is abstracted and exposed as a set of planes, CRTCs,
>> 395 encoders and connectors. KMS drivers must thus create and initialize all
>> 396 those objects at load time after initializing mode setting.
>> 397
>> 398 CRTCs (:c:type:`struct drm_crtc <drm_crtc>`)
>> 399 --------------------------------------------
>> 400
>> 401 A CRTC is an abstraction representing a part of the chip that contains a
>> 402 pointer to a scanout buffer. Therefore, the number of CRTCs available
>> 403 determines how many independent scanout buffers can be active at any
>> 404 given time. The CRTC structure contains several fields to support this:
>> 405 a pointer to some video memory (abstracted as a frame buffer object), a
>> 406 display mode, and an (x, y) offset into the video memory to support
>> 407 panning or configurations where one piece of video memory spans multiple
>> 408 CRTCs.
>> 409
>> 410 CRTC Initialization
>> 411 ~~~~~~~~~~~~~~~~~~~
>> 412
>> 413 A KMS device must create and register at least one struct
>> 414 :c:type:`struct drm_crtc <drm_crtc>` instance. The instance is
>> 415 allocated and zeroed by the driver, possibly as part of a larger
>> 416 structure, and registered with a call to :c:func:`drm_crtc_init()`
>> 417 with a pointer to CRTC functions.
>> 418
>> 419
>> 420 Cleanup
>> 421 -------
>> 422
>> 423 The DRM core manages its objects' lifetime. When an object is not needed
>> 424 anymore the core calls its destroy function, which must clean up and
>> 425 free every resource allocated for the object. Every
>> 426 :c:func:`drm_\*_init()` call must be matched with a corresponding
>> 427 :c:func:`drm_\*_cleanup()` call to cleanup CRTCs
>> 428 (:c:func:`drm_crtc_cleanup()`), planes
>> 429 (:c:func:`drm_plane_cleanup()`), encoders
>> 430 (:c:func:`drm_encoder_cleanup()`) and connectors
>> 431 (:c:func:`drm_connector_cleanup()`). Furthermore, connectors that
>> 432 have been added to sysfs must be removed by a call to
>> 433 :c:func:`drm_connector_unregister()` before calling
>> 434 :c:func:`drm_connector_cleanup()`.
>> 435
>> 436 Connectors state change detection must be cleanup up with a call to
>> 437 :c:func:`drm_kms_helper_poll_fini()`.
>> 438
>> 439 Output discovery and initialization example
>> 440 -------------------------------------------
>> 441
>> 442 .. code-block:: c
>> 443
>> 444 void intel_crt_init(struct drm_device *dev)
>> 445 {
>> 446 struct drm_connector *connector;
>> 447 struct intel_output *intel_output;
>> 448
>> 449 intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
>> 450 if (!intel_output)
>> 451 return;
>> 452
>> 453 connector = &intel_output->base;
>> 454 drm_connector_init(dev, &intel_output->base,
>> 455 &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);
>> 456
>> 457 drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs,
>> 458 DRM_MODE_ENCODER_DAC);
>> 459
>> 460 drm_mode_connector_attach_encoder(&intel_output->base,
>> 461 &intel_output->enc);
>> 462
>> 463 /* Set up the DDC bus. */
>> 464 intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A");
>> 465 if (!intel_output->ddc_bus) {
>> 466 dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
>> 467 "failed.\n");
>> 468 return;
>> 469 }
>> 470
>> 471 intel_output->type = INTEL_OUTPUT_ANALOG;
>> 472 connector->interlace_allowed = 0;
>> 473 connector->doublescan_allowed = 0;
>> 474
>> 475 drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs);
>> 476 drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);
>> 477
>> 478 drm_connector_register(connector);
>> 479 }
>> 480
>> 481 In the example above (taken from the i915 driver), a CRTC, connector and
>> 482 encoder combination is created. A device-specific i2c bus is also
>> 483 created for fetching EDID data and performing monitor detection. Once
>> 484 the process is complete, the new connector is registered with sysfs to
>> 485 make its properties available to applications.
>> 486
467 KMS Locking 487 KMS Locking
468 =========== 488 ===========
469 489
470 .. kernel-doc:: drivers/gpu/drm/drm_modeset_lo 490 .. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c
471 :doc: kms locking 491 :doc: kms locking
472 492
473 .. kernel-doc:: include/drm/drm_modeset_lock.h 493 .. kernel-doc:: include/drm/drm_modeset_lock.h
474 :internal: 494 :internal:
475 495
476 .. kernel-doc:: drivers/gpu/drm/drm_modeset_lo 496 .. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c
477 :export: 497 :export:
478 498
479 KMS Properties 499 KMS Properties
480 ============== 500 ==============
481 501
482 This section of the documentation is primarily <<
483 For the driver APIs, see the other sections. <<
484 <<
485 Requirements <<
486 ------------ <<
487 <<
488 KMS drivers might need to add extra properties <<
489 new property introduced in a driver needs to m <<
490 addition to the one mentioned above: <<
491 <<
492 * It must be standardized, documenting: <<
493 <<
494 * The full, exact, name string; <<
495 * If the property is an enum, all the valid <<
496 * What values are accepted, and what these v <<
497 * What the property does and how it can be u <<
498 * How the property might interact with other <<
499 <<
500 * It must provide a generic helper in the core <<
501 property on the object it attaches to. <<
502 <<
503 * Its content must be decoded by the core and <<
504 associated state structure. That includes an <<
505 to precompute, like struct drm_clip_rect for <<
506 <<
507 * Its initial state must match the behavior pr <<
508 introduction. This might be a fixed value ma <<
509 does, or it may be inherited from the state <<
510 system in during boot. <<
511 <<
512 * An IGT test must be submitted where reasonab <<
513 <<
514 For historical reasons, non-standard, driver-s <<
515 driver wants to add support for one of those p <<
516 new properties apply where possible. Additiona <<
517 match the de facto semantics of the existing p <<
518 Developers of the driver that first added the <<
519 tasks and must ACK the documented behavior if <<
520 <<
521 Property Types and Blob Property Support 502 Property Types and Blob Property Support
522 ---------------------------------------- 503 ----------------------------------------
523 504
524 .. kernel-doc:: drivers/gpu/drm/drm_property.c 505 .. kernel-doc:: drivers/gpu/drm/drm_property.c
525 :doc: overview 506 :doc: overview
526 507
527 .. kernel-doc:: include/drm/drm_property.h 508 .. kernel-doc:: include/drm/drm_property.h
528 :internal: 509 :internal:
529 510
530 .. kernel-doc:: drivers/gpu/drm/drm_property.c 511 .. kernel-doc:: drivers/gpu/drm/drm_property.c
531 :export: 512 :export:
532 513
533 .. _standard_connector_properties: <<
534 <<
535 Standard Connector Properties 514 Standard Connector Properties
536 ----------------------------- 515 -----------------------------
537 516
538 .. kernel-doc:: drivers/gpu/drm/drm_connector. 517 .. kernel-doc:: drivers/gpu/drm/drm_connector.c
539 :doc: standard connector properties 518 :doc: standard connector properties
540 519
541 HDMI Specific Connector Properties <<
542 ---------------------------------- <<
543 <<
544 .. kernel-doc:: drivers/gpu/drm/drm_connector. <<
545 :doc: HDMI connector properties <<
546 <<
547 Analog TV Specific Connector Properties <<
548 --------------------------------------- <<
549 <<
550 .. kernel-doc:: drivers/gpu/drm/drm_connector. <<
551 :doc: Analog TV Connector Properties <<
552 <<
553 Standard CRTC Properties <<
554 ------------------------ <<
555 <<
556 .. kernel-doc:: drivers/gpu/drm/drm_crtc.c <<
557 :doc: standard CRTC properties <<
558 <<
559 Standard Plane Properties <<
560 ------------------------- <<
561 <<
562 .. kernel-doc:: drivers/gpu/drm/drm_plane.c <<
563 :doc: standard plane properties <<
564 <<
565 .. _plane_composition_properties: <<
566 <<
567 Plane Composition Properties 520 Plane Composition Properties
568 ---------------------------- 521 ----------------------------
569 522
570 .. kernel-doc:: drivers/gpu/drm/drm_blend.c 523 .. kernel-doc:: drivers/gpu/drm/drm_blend.c
571 :doc: overview 524 :doc: overview
572 525
573 .. _damage_tracking_properties: !! 526 .. kernel-doc:: drivers/gpu/drm/drm_blend.c
574 !! 527 :export:
575 Damage Tracking Properties <<
576 -------------------------- <<
577 <<
578 .. kernel-doc:: drivers/gpu/drm/drm_plane.c <<
579 :doc: damage tracking <<
580 528
581 Color Management Properties 529 Color Management Properties
582 --------------------------- 530 ---------------------------
583 531
584 .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt 532 .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
585 :doc: overview 533 :doc: overview
586 534
>> 535 .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
>> 536 :export:
>> 537
587 Tile Group Property 538 Tile Group Property
588 ------------------- 539 -------------------
589 540
590 .. kernel-doc:: drivers/gpu/drm/drm_connector. 541 .. kernel-doc:: drivers/gpu/drm/drm_connector.c
591 :doc: Tile group 542 :doc: Tile group
592 543
593 Explicit Fencing Properties 544 Explicit Fencing Properties
594 --------------------------- 545 ---------------------------
595 546
596 .. kernel-doc:: drivers/gpu/drm/drm_atomic_uap !! 547 .. kernel-doc:: drivers/gpu/drm/drm_atomic.c
597 :doc: explicit fencing properties 548 :doc: explicit fencing properties
598 549
599 <<
600 Variable Refresh Properties <<
601 --------------------------- <<
602 <<
603 .. kernel-doc:: drivers/gpu/drm/drm_connector. <<
604 :doc: Variable refresh properties <<
605 <<
606 Cursor Hotspot Properties <<
607 --------------------------- <<
608 <<
609 .. kernel-doc:: drivers/gpu/drm/drm_plane.c <<
610 :doc: hotspot properties <<
611 <<
612 Existing KMS Properties 550 Existing KMS Properties
613 ----------------------- 551 -----------------------
614 552
615 The following table gives description of drm p 553 The following table gives description of drm properties exposed by various
616 modules/drivers. Because this table is very un 554 modules/drivers. Because this table is very unwieldy, do not add any new
617 properties here. Instead document them in a se 555 properties here. Instead document them in a section above.
618 556
619 .. csv-table:: 557 .. csv-table::
620 :header-rows: 1 558 :header-rows: 1
621 :file: kms-properties.csv 559 :file: kms-properties.csv
622 560
623 Vertical Blanking 561 Vertical Blanking
624 ================= 562 =================
625 563
626 .. kernel-doc:: drivers/gpu/drm/drm_vblank.c 564 .. kernel-doc:: drivers/gpu/drm/drm_vblank.c
627 :doc: vblank handling 565 :doc: vblank handling
628 566
629 Vertical Blanking and Interrupt Handling Funct 567 Vertical Blanking and Interrupt Handling Functions Reference
630 ---------------------------------------------- 568 ------------------------------------------------------------
631 569
632 .. kernel-doc:: include/drm/drm_vblank.h 570 .. kernel-doc:: include/drm/drm_vblank.h
633 :internal: 571 :internal:
634 572
635 .. kernel-doc:: drivers/gpu/drm/drm_vblank.c 573 .. kernel-doc:: drivers/gpu/drm/drm_vblank.c
636 :export: <<
637 <<
638 Vertical Blank Work <<
639 =================== <<
640 <<
641 .. kernel-doc:: drivers/gpu/drm/drm_vblank_wor <<
642 :doc: vblank works <<
643 <<
644 Vertical Blank Work Functions Reference <<
645 --------------------------------------- <<
646 <<
647 .. kernel-doc:: include/drm/drm_vblank_work.h <<
648 :internal: <<
649 <<
650 .. kernel-doc:: drivers/gpu/drm/drm_vblank_wor <<
651 :export: 574 :export:
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