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