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Diffstat (limited to 'Documentation/DocBook/drm.tmpl')
-rw-r--r--Documentation/DocBook/drm.tmpl308
1 files changed, 168 insertions, 140 deletions
diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index c27915893974..196b8b9dba11 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -32,7 +32,7 @@
32 The Linux DRM layer contains code intended to support the needs 32 The Linux DRM layer contains code intended to support the needs
33 of complex graphics devices, usually containing programmable 33 of complex graphics devices, usually containing programmable
34 pipelines well suited to 3D graphics acceleration. Graphics 34 pipelines well suited to 3D graphics acceleration. Graphics
35 drivers in the kernel can make use of DRM functions to make 35 drivers in the kernel may make use of DRM functions to make
36 tasks like memory management, interrupt handling and DMA easier, 36 tasks like memory management, interrupt handling and DMA easier,
37 and provide a uniform interface to applications. 37 and provide a uniform interface to applications.
38 </para> 38 </para>
@@ -57,10 +57,10 @@
57 existing drivers. 57 existing drivers.
58 </para> 58 </para>
59 <para> 59 <para>
60 First, we'll go over some typical driver initialization 60 First, we go over some typical driver initialization
61 requirements, like setting up command buffers, creating an 61 requirements, like setting up command buffers, creating an
62 initial output configuration, and initializing core services. 62 initial output configuration, and initializing core services.
63 Subsequent sections will cover core internals in more detail, 63 Subsequent sections cover core internals in more detail,
64 providing implementation notes and examples. 64 providing implementation notes and examples.
65 </para> 65 </para>
66 <para> 66 <para>
@@ -74,7 +74,7 @@
74 </para> 74 </para>
75 <para> 75 <para>
76 The core of every DRM driver is struct drm_driver. Drivers 76 The core of every DRM driver is struct drm_driver. Drivers
77 will typically statically initialize a drm_driver structure, 77 typically statically initialize a drm_driver structure,
78 then pass it to drm_init() at load time. 78 then pass it to drm_init() at load time.
79 </para> 79 </para>
80 80
@@ -88,8 +88,8 @@
88 </para> 88 </para>
89 <programlisting> 89 <programlisting>
90 static struct drm_driver driver = { 90 static struct drm_driver driver = {
91 /* don't use mtrr's here, the Xserver or user space app should 91 /* Don't use MTRRs here; the Xserver or userspace app should
92 * deal with them for intel hardware. 92 * deal with them for Intel hardware.
93 */ 93 */
94 .driver_features = 94 .driver_features =
95 DRIVER_USE_AGP | DRIVER_REQUIRE_AGP | 95 DRIVER_USE_AGP | DRIVER_REQUIRE_AGP |
@@ -154,8 +154,8 @@
154 </programlisting> 154 </programlisting>
155 <para> 155 <para>
156 In the example above, taken from the i915 DRM driver, the driver 156 In the example above, taken from the i915 DRM driver, the driver
157 sets several flags indicating what core features it supports. 157 sets several flags indicating what core features it supports;
158 We'll go over the individual callbacks in later sections. Since 158 we go over the individual callbacks in later sections. Since
159 flags indicate which features your driver supports to the DRM 159 flags indicate which features your driver supports to the DRM
160 core, you need to set most of them prior to calling drm_init(). Some, 160 core, you need to set most of them prior to calling drm_init(). Some,
161 like DRIVER_MODESET can be set later based on user supplied parameters, 161 like DRIVER_MODESET can be set later based on user supplied parameters,
@@ -203,8 +203,8 @@
203 <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term> 203 <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
204 <listitem> 204 <listitem>
205 <para> 205 <para>
206 DRIVER_HAVE_IRQ indicates whether the driver has a IRQ 206 DRIVER_HAVE_IRQ indicates whether the driver has an IRQ
207 handler, DRIVER_IRQ_SHARED indicates whether the device &amp; 207 handler. DRIVER_IRQ_SHARED indicates whether the device &amp;
208 handler support shared IRQs (note that this is required of 208 handler support shared IRQs (note that this is required of
209 PCI drivers). 209 PCI drivers).
210 </para> 210 </para>
@@ -214,8 +214,8 @@
214 <term>DRIVER_DMA_QUEUE</term> 214 <term>DRIVER_DMA_QUEUE</term>
215 <listitem> 215 <listitem>
216 <para> 216 <para>
217 If the driver queues DMA requests and completes them 217 Should be set if the driver queues DMA requests and completes them
218 asynchronously, this flag should be set. Deprecated. 218 asynchronously. Deprecated.
219 </para> 219 </para>
220 </listitem> 220 </listitem>
221 </varlistentry> 221 </varlistentry>
@@ -238,7 +238,7 @@
238 </variablelist> 238 </variablelist>
239 <para> 239 <para>
240 In this specific case, the driver requires AGP and supports 240 In this specific case, the driver requires AGP and supports
241 IRQs. DMA, as we'll see, is handled by device specific ioctls 241 IRQs. DMA, as discussed later, is handled by device-specific ioctls
242 in this case. It also supports the kernel mode setting APIs, though 242 in this case. It also supports the kernel mode setting APIs, though
243 unlike in the actual i915 driver source, this example unconditionally 243 unlike in the actual i915 driver source, this example unconditionally
244 exports KMS capability. 244 exports KMS capability.
@@ -269,36 +269,34 @@
269 initial output configuration. 269 initial output configuration.
270 </para> 270 </para>
271 <para> 271 <para>
272 Note that the tasks performed at driver load time must not 272 If compatibility is a concern (e.g. with drivers converted over
273 conflict with DRM client requirements. For instance, if user 273 to the new interfaces from the old ones), care must be taken to
274 prevent device initialization and control that is incompatible with
275 currently active userspace drivers. For instance, if user
274 level mode setting drivers are in use, it would be problematic 276 level mode setting drivers are in use, it would be problematic
275 to perform output discovery &amp; configuration at load time. 277 to perform output discovery &amp; configuration at load time.
276 Likewise, if pre-memory management aware user level drivers are 278 Likewise, if user-level drivers unaware of memory management are
277 in use, memory management and command buffer setup may need to 279 in use, memory management and command buffer setup may need to
278 be omitted. These requirements are driver specific, and care 280 be omitted. These requirements are driver-specific, and care
279 needs to be taken to keep both old and new applications and 281 needs to be taken to keep both old and new applications and
280 libraries working. The i915 driver supports the "modeset" 282 libraries working. The i915 driver supports the "modeset"
281 module parameter to control whether advanced features are 283 module parameter to control whether advanced features are
282 enabled at load time or in legacy fashion. If compatibility is 284 enabled at load time or in legacy fashion.
283 a concern (e.g. with drivers converted over to the new interfaces
284 from the old ones), care must be taken to prevent incompatible
285 device initialization and control with the currently active
286 userspace drivers.
287 </para> 285 </para>
288 286
289 <sect2> 287 <sect2>
290 <title>Driver private &amp; performance counters</title> 288 <title>Driver private &amp; performance counters</title>
291 <para> 289 <para>
292 The driver private hangs off the main drm_device structure and 290 The driver private hangs off the main drm_device structure and
293 can be used for tracking various device specific bits of 291 can be used for tracking various device-specific bits of
294 information, like register offsets, command buffer status, 292 information, like register offsets, command buffer status,
295 register state for suspend/resume, etc. At load time, a 293 register state for suspend/resume, etc. At load time, a
296 driver can simply allocate one and set drm_device.dev_priv 294 driver may simply allocate one and set drm_device.dev_priv
297 appropriately; at unload the driver can free it and set 295 appropriately; it should be freed and drm_device.dev_priv set
298 drm_device.dev_priv to NULL. 296 to NULL when the driver is unloaded.
299 </para> 297 </para>
300 <para> 298 <para>
301 The DRM supports several counters which can be used for rough 299 The DRM supports several counters which may be used for rough
302 performance characterization. Note that the DRM stat counter 300 performance characterization. Note that the DRM stat counter
303 system is not often used by applications, and supporting 301 system is not often used by applications, and supporting
304 additional counters is completely optional. 302 additional counters is completely optional.
@@ -307,15 +305,15 @@
307 These interfaces are deprecated and should not be used. If performance 305 These interfaces are deprecated and should not be used. If performance
308 monitoring is desired, the developer should investigate and 306 monitoring is desired, the developer should investigate and
309 potentially enhance the kernel perf and tracing infrastructure to export 307 potentially enhance the kernel perf and tracing infrastructure to export
310 GPU related performance information to performance monitoring 308 GPU related performance information for consumption by performance
311 tools and applications. 309 monitoring tools and applications.
312 </para> 310 </para>
313 </sect2> 311 </sect2>
314 312
315 <sect2> 313 <sect2>
316 <title>Configuring the device</title> 314 <title>Configuring the device</title>
317 <para> 315 <para>
318 Obviously, device configuration will be device specific. 316 Obviously, device configuration is device-specific.
319 However, there are several common operations: finding a 317 However, there are several common operations: finding a
320 device's PCI resources, mapping them, and potentially setting 318 device's PCI resources, mapping them, and potentially setting
321 up an IRQ handler. 319 up an IRQ handler.
@@ -323,10 +321,10 @@
323 <para> 321 <para>
324 Finding &amp; mapping resources is fairly straightforward. The 322 Finding &amp; mapping resources is fairly straightforward. The
325 DRM wrapper functions, drm_get_resource_start() and 323 DRM wrapper functions, drm_get_resource_start() and
326 drm_get_resource_len() can be used to find BARs on the given 324 drm_get_resource_len(), may be used to find BARs on the given
327 drm_device struct. Once those values have been retrieved, the 325 drm_device struct. Once those values have been retrieved, the
328 driver load function can call drm_addmap() to create a new 326 driver load function can call drm_addmap() to create a new
329 mapping for the BAR in question. Note you'll probably want a 327 mapping for the BAR in question. Note that you probably want a
330 drm_local_map_t in your driver private structure to track any 328 drm_local_map_t in your driver private structure to track any
331 mappings you create. 329 mappings you create.
332<!-- !Fdrivers/gpu/drm/drm_bufs.c drm_get_resource_* --> 330<!-- !Fdrivers/gpu/drm/drm_bufs.c drm_get_resource_* -->
@@ -335,20 +333,20 @@
335 <para> 333 <para>
336 if compatibility with other operating systems isn't a concern 334 if compatibility with other operating systems isn't a concern
337 (DRM drivers can run under various BSD variants and OpenSolaris), 335 (DRM drivers can run under various BSD variants and OpenSolaris),
338 native Linux calls can be used for the above, e.g. pci_resource_* 336 native Linux calls may be used for the above, e.g. pci_resource_*
339 and iomap*/iounmap. See the Linux device driver book for more 337 and iomap*/iounmap. See the Linux device driver book for more
340 info. 338 info.
341 </para> 339 </para>
342 <para> 340 <para>
343 Once you have a register map, you can use the DRM_READn() and 341 Once you have a register map, you may use the DRM_READn() and
344 DRM_WRITEn() macros to access the registers on your device, or 342 DRM_WRITEn() macros to access the registers on your device, or
345 use driver specific versions to offset into your MMIO space 343 use driver-specific versions to offset into your MMIO space
346 relative to a driver specific base pointer (see I915_READ for 344 relative to a driver-specific base pointer (see I915_READ for
347 example). 345 an example).
348 </para> 346 </para>
349 <para> 347 <para>
350 If your device supports interrupt generation, you may want to 348 If your device supports interrupt generation, you may want to
351 setup an interrupt handler at driver load time as well. This 349 set up an interrupt handler when the driver is loaded. This
352 is done using the drm_irq_install() function. If your device 350 is done using the drm_irq_install() function. If your device
353 supports vertical blank interrupts, it should call 351 supports vertical blank interrupts, it should call
354 drm_vblank_init() to initialize the core vblank handling code before 352 drm_vblank_init() to initialize the core vblank handling code before
@@ -357,7 +355,7 @@
357 </para> 355 </para>
358<!--!Fdrivers/char/drm/drm_irq.c drm_irq_install--> 356<!--!Fdrivers/char/drm/drm_irq.c drm_irq_install-->
359 <para> 357 <para>
360 Once your interrupt handler is registered (it'll use your 358 Once your interrupt handler is registered (it uses your
361 drm_driver.irq_handler as the actual interrupt handling 359 drm_driver.irq_handler as the actual interrupt handling
362 function), you can safely enable interrupts on your device, 360 function), you can safely enable interrupts on your device,
363 assuming any other state your interrupt handler uses is also 361 assuming any other state your interrupt handler uses is also
@@ -371,10 +369,10 @@
371 using the pci_map_rom() call, a convenience function that 369 using the pci_map_rom() call, a convenience function that
372 takes care of mapping the actual ROM, whether it has been 370 takes care of mapping the actual ROM, whether it has been
373 shadowed into memory (typically at address 0xc0000) or exists 371 shadowed into memory (typically at address 0xc0000) or exists
374 on the PCI device in the ROM BAR. Note that once you've 372 on the PCI device in the ROM BAR. Note that after the ROM
375 mapped the ROM and extracted any necessary information, be 373 has been mapped and any necessary information has been extracted,
376 sure to unmap it; on many devices the ROM address decoder is 374 it should be unmapped; on many devices, the ROM address decoder is
377 shared with other BARs, so leaving it mapped can cause 375 shared with other BARs, so leaving it mapped could cause
378 undesired behavior like hangs or memory corruption. 376 undesired behavior like hangs or memory corruption.
379<!--!Fdrivers/pci/rom.c pci_map_rom--> 377<!--!Fdrivers/pci/rom.c pci_map_rom-->
380 </para> 378 </para>
@@ -389,9 +387,9 @@
389 should support a memory manager. 387 should support a memory manager.
390 </para> 388 </para>
391 <para> 389 <para>
392 If your driver supports memory management (it should!), you'll 390 If your driver supports memory management (it should!), you
393 need to set that up at load time as well. How you initialize 391 need to set that up at load time as well. How you initialize
394 it depends on which memory manager you're using, TTM or GEM. 392 it depends on which memory manager you're using: TTM or GEM.
395 </para> 393 </para>
396 <sect3> 394 <sect3>
397 <title>TTM initialization</title> 395 <title>TTM initialization</title>
@@ -401,7 +399,7 @@
401 and devices with dedicated video RAM (VRAM), i.e. most discrete 399 and devices with dedicated video RAM (VRAM), i.e. most discrete
402 graphics devices. If your device has dedicated RAM, supporting 400 graphics devices. If your device has dedicated RAM, supporting
403 TTM is desirable. TTM also integrates tightly with your 401 TTM is desirable. TTM also integrates tightly with your
404 driver specific buffer execution function. See the radeon 402 driver-specific buffer execution function. See the radeon
405 driver for examples. 403 driver for examples.
406 </para> 404 </para>
407 <para> 405 <para>
@@ -429,21 +427,21 @@
429 created by the memory manager at runtime. Your global TTM should 427 created by the memory manager at runtime. Your global TTM should
430 have a type of TTM_GLOBAL_TTM_MEM. The size field for the global 428 have a type of TTM_GLOBAL_TTM_MEM. The size field for the global
431 object should be sizeof(struct ttm_mem_global), and the init and 429 object should be sizeof(struct ttm_mem_global), and the init and
432 release hooks should point at your driver specific init and 430 release hooks should point at your driver-specific init and
433 release routines, which will probably eventually call 431 release routines, which probably eventually call
434 ttm_mem_global_init and ttm_mem_global_release respectively. 432 ttm_mem_global_init and ttm_mem_global_release, respectively.
435 </para> 433 </para>
436 <para> 434 <para>
437 Once your global TTM accounting structure is set up and initialized 435 Once your global TTM accounting structure is set up and initialized
438 (done by calling ttm_global_item_ref on the global object you 436 by calling ttm_global_item_ref() on it,
439 just created), you'll need to create a buffer object TTM to 437 you need to create a buffer object TTM to
440 provide a pool for buffer object allocation by clients and the 438 provide a pool for buffer object allocation by clients and the
441 kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO, 439 kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO,
442 and its size should be sizeof(struct ttm_bo_global). Again, 440 and its size should be sizeof(struct ttm_bo_global). Again,
443 driver specific init and release functions can be provided, 441 driver-specific init and release functions may be provided,
444 likely eventually calling ttm_bo_global_init and 442 likely eventually calling ttm_bo_global_init() and
445 ttm_bo_global_release, respectively. Also like the previous 443 ttm_bo_global_release(), respectively. Also, like the previous
446 object, ttm_global_item_ref is used to create an initial reference 444 object, ttm_global_item_ref() is used to create an initial reference
447 count for the TTM, which will call your initialization function. 445 count for the TTM, which will call your initialization function.
448 </para> 446 </para>
449 </sect3> 447 </sect3>
@@ -453,27 +451,26 @@
453 GEM is an alternative to TTM, designed specifically for UMA 451 GEM is an alternative to TTM, designed specifically for UMA
454 devices. It has simpler initialization and execution requirements 452 devices. It has simpler initialization and execution requirements
455 than TTM, but has no VRAM management capability. Core GEM 453 than TTM, but has no VRAM management capability. Core GEM
456 initialization is comprised of a basic drm_mm_init call to create 454 is initialized by calling drm_mm_init() to create
457 a GTT DRM MM object, which provides an address space pool for 455 a GTT DRM MM object, which provides an address space pool for
458 object allocation. In a KMS configuration, the driver will 456 object allocation. In a KMS configuration, the driver
459 need to allocate and initialize a command ring buffer following 457 needs to allocate and initialize a command ring buffer following
460 basic GEM initialization. Most UMA devices have a so-called 458 core GEM initialization. A UMA device usually has what is called a
461 "stolen" memory region, which provides space for the initial 459 "stolen" memory region, which provides space for the initial
462 framebuffer and large, contiguous memory regions required by the 460 framebuffer and large, contiguous memory regions required by the
463 device. This space is not typically managed by GEM, and must 461 device. This space is not typically managed by GEM, and it must
464 be initialized separately into its own DRM MM object. 462 be initialized separately into its own DRM MM object.
465 </para> 463 </para>
466 <para> 464 <para>
467 Initialization will be driver specific, and will depend on 465 Initialization is driver-specific. In the case of Intel
468 the architecture of the device. In the case of Intel
469 integrated graphics chips like 965GM, GEM initialization can 466 integrated graphics chips like 965GM, GEM initialization can
470 be done by calling the internal GEM init function, 467 be done by calling the internal GEM init function,
471 i915_gem_do_init(). Since the 965GM is a UMA device 468 i915_gem_do_init(). Since the 965GM is a UMA device
472 (i.e. it doesn't have dedicated VRAM), GEM will manage 469 (i.e. it doesn't have dedicated VRAM), GEM manages
473 making regular RAM available for GPU operations. Memory set 470 making regular RAM available for GPU operations. Memory set
474 aside by the BIOS (called "stolen" memory by the i915 471 aside by the BIOS (called "stolen" memory by the i915
475 driver) will be managed by the DRM memrange allocator; the 472 driver) is managed by the DRM memrange allocator; the
476 rest of the aperture will be managed by GEM. 473 rest of the aperture is managed by GEM.
477 <programlisting> 474 <programlisting>
478 /* Basic memrange allocator for stolen space (aka vram) */ 475 /* Basic memrange allocator for stolen space (aka vram) */
479 drm_memrange_init(&amp;dev_priv->vram, 0, prealloc_size); 476 drm_memrange_init(&amp;dev_priv->vram, 0, prealloc_size);
@@ -483,7 +480,7 @@
483<!--!Edrivers/char/drm/drm_memrange.c--> 480<!--!Edrivers/char/drm/drm_memrange.c-->
484 </para> 481 </para>
485 <para> 482 <para>
486 Once the memory manager has been set up, we can allocate the 483 Once the memory manager has been set up, we may allocate the
487 command buffer. In the i915 case, this is also done with a 484 command buffer. In the i915 case, this is also done with a
488 GEM function, i915_gem_init_ringbuffer(). 485 GEM function, i915_gem_init_ringbuffer().
489 </para> 486 </para>
@@ -493,16 +490,25 @@
493 <sect2> 490 <sect2>
494 <title>Output configuration</title> 491 <title>Output configuration</title>
495 <para> 492 <para>
496 The final initialization task is output configuration. This involves 493 The final initialization task is output configuration. This involves:
497 finding and initializing the CRTCs, encoders and connectors 494 <itemizedlist>
498 for your device, creating an initial configuration and 495 <listitem>
499 registering a framebuffer console driver. 496 Finding and initializing the CRTCs, encoders, and connectors
497 for the device.
498 </listitem>
499 <listitem>
500 Creating an initial configuration.
501 </listitem>
502 <listitem>
503 Registering a framebuffer console driver.
504 </listitem>
505 </itemizedlist>
500 </para> 506 </para>
501 <sect3> 507 <sect3>
502 <title>Output discovery and initialization</title> 508 <title>Output discovery and initialization</title>
503 <para> 509 <para>
504 Several core functions exist to create CRTCs, encoders and 510 Several core functions exist to create CRTCs, encoders, and
505 connectors, namely drm_crtc_init(), drm_connector_init() and 511 connectors, namely: drm_crtc_init(), drm_connector_init(), and
506 drm_encoder_init(), along with several "helper" functions to 512 drm_encoder_init(), along with several "helper" functions to
507 perform common tasks. 513 perform common tasks.
508 </para> 514 </para>
@@ -555,10 +561,10 @@ void intel_crt_init(struct drm_device *dev)
555 </programlisting> 561 </programlisting>
556 <para> 562 <para>
557 In the example above (again, taken from the i915 driver), a 563 In the example above (again, taken from the i915 driver), a
558 CRT connector and encoder combination is created. A device 564 CRT connector and encoder combination is created. A device-specific
559 specific i2c bus is also created, for fetching EDID data and 565 i2c bus is also created for fetching EDID data and
560 performing monitor detection. Once the process is complete, 566 performing monitor detection. Once the process is complete,
561 the new connector is registered with sysfs, to make its 567 the new connector is registered with sysfs to make its
562 properties available to applications. 568 properties available to applications.
563 </para> 569 </para>
564 <sect4> 570 <sect4>
@@ -567,12 +573,12 @@ void intel_crt_init(struct drm_device *dev)
567 Since many PC-class graphics devices have similar display output 573 Since many PC-class graphics devices have similar display output
568 designs, the DRM provides a set of helper functions to make 574 designs, the DRM provides a set of helper functions to make
569 output management easier. The core helper routines handle 575 output management easier. The core helper routines handle
570 encoder re-routing and disabling of unused functions following 576 encoder re-routing and the disabling of unused functions following
571 mode set. Using the helpers is optional, but recommended for 577 mode setting. Using the helpers is optional, but recommended for
572 devices with PC-style architectures (i.e. a set of display planes 578 devices with PC-style architectures (i.e. a set of display planes
573 for feeding pixels to encoders which are in turn routed to 579 for feeding pixels to encoders which are in turn routed to
574 connectors). Devices with more complex requirements needing 580 connectors). Devices with more complex requirements needing
575 finer grained management can opt to use the core callbacks 581 finer grained management may opt to use the core callbacks
576 directly. 582 directly.
577 </para> 583 </para>
578 <para> 584 <para>
@@ -580,17 +586,25 @@ void intel_crt_init(struct drm_device *dev)
580 </para> 586 </para>
581 </sect4> 587 </sect4>
582 <para> 588 <para>
583 For each encoder, CRTC and connector, several functions must 589 Each encoder object needs to provide:
584 be provided, depending on the object type. Encoder objects 590 <itemizedlist>
585 need to provide a DPMS (basically on/off) function, mode fixup 591 <listitem>
586 (for converting requested modes into native hardware timings), 592 A DPMS (basically on/off) function.
587 and prepare, set and commit functions for use by the core DRM 593 </listitem>
588 helper functions. Connector helpers need to provide mode fetch and 594 <listitem>
589 validity functions as well as an encoder matching function for 595 A mode-fixup function (for converting requested modes into
590 returning an ideal encoder for a given connector. The core 596 native hardware timings).
591 connector functions include a DPMS callback, (deprecated) 597 </listitem>
592 save/restore routines, detection, mode probing, property handling, 598 <listitem>
593 and cleanup functions. 599 Functions (prepare, set, and commit) for use by the core DRM
600 helper functions.
601 </listitem>
602 </itemizedlist>
603 Connector helpers need to provide functions (mode-fetch, validity,
604 and encoder-matching) for returning an ideal encoder for a given
605 connector. The core connector functions include a DPMS callback,
606 save/restore routines (deprecated), detection, mode probing,
607 property handling, and cleanup functions.
594 </para> 608 </para>
595<!--!Edrivers/char/drm/drm_crtc.h--> 609<!--!Edrivers/char/drm/drm_crtc.h-->
596<!--!Edrivers/char/drm/drm_crtc.c--> 610<!--!Edrivers/char/drm/drm_crtc.c-->
@@ -605,23 +619,34 @@ void intel_crt_init(struct drm_device *dev)
605 <title>VBlank event handling</title> 619 <title>VBlank event handling</title>
606 <para> 620 <para>
607 The DRM core exposes two vertical blank related ioctls: 621 The DRM core exposes two vertical blank related ioctls:
608 DRM_IOCTL_WAIT_VBLANK and DRM_IOCTL_MODESET_CTL. 622 <variablelist>
623 <varlistentry>
624 <term>DRM_IOCTL_WAIT_VBLANK</term>
625 <listitem>
626 <para>
627 This takes a struct drm_wait_vblank structure as its argument,
628 and it is used to block or request a signal when a specified
629 vblank event occurs.
630 </para>
631 </listitem>
632 </varlistentry>
633 <varlistentry>
634 <term>DRM_IOCTL_MODESET_CTL</term>
635 <listitem>
636 <para>
637 This should be called by application level drivers before and
638 after mode setting, since on many devices the vertical blank
639 counter is reset at that time. Internally, the DRM snapshots
640 the last vblank count when the ioctl is called with the
641 _DRM_PRE_MODESET command, so that the counter won't go backwards
642 (which is dealt with when _DRM_POST_MODESET is used).
643 </para>
644 </listitem>
645 </varlistentry>
646 </variablelist>
609<!--!Edrivers/char/drm/drm_irq.c--> 647<!--!Edrivers/char/drm/drm_irq.c-->
610 </para> 648 </para>
611 <para> 649 <para>
612 DRM_IOCTL_WAIT_VBLANK takes a struct drm_wait_vblank structure
613 as its argument, and is used to block or request a signal when a
614 specified vblank event occurs.
615 </para>
616 <para>
617 DRM_IOCTL_MODESET_CTL should be called by application level
618 drivers before and after mode setting, since on many devices the
619 vertical blank counter will be reset at that time. Internally,
620 the DRM snapshots the last vblank count when the ioctl is called
621 with the _DRM_PRE_MODESET command so that the counter won't go
622 backwards (which is dealt with when _DRM_POST_MODESET is used).
623 </para>
624 <para>
625 To support the functions above, the DRM core provides several 650 To support the functions above, the DRM core provides several
626 helper functions for tracking vertical blank counters, and 651 helper functions for tracking vertical blank counters, and
627 requires drivers to provide several callbacks: 652 requires drivers to provide several callbacks:
@@ -632,24 +657,24 @@ void intel_crt_init(struct drm_device *dev)
632 register. The enable and disable vblank callbacks should enable 657 register. The enable and disable vblank callbacks should enable
633 and disable vertical blank interrupts, respectively. In the 658 and disable vertical blank interrupts, respectively. In the
634 absence of DRM clients waiting on vblank events, the core DRM 659 absence of DRM clients waiting on vblank events, the core DRM
635 code will use the disable_vblank() function to disable 660 code uses the disable_vblank() function to disable
636 interrupts, which saves power. They'll be re-enabled again when 661 interrupts, which saves power. They are re-enabled again when
637 a client calls the vblank wait ioctl above. 662 a client calls the vblank wait ioctl above.
638 </para> 663 </para>
639 <para> 664 <para>
640 Devices that don't provide a count register can simply use an 665 A device that doesn't provide a count register may simply use an
641 internal atomic counter incremented on every vertical blank 666 internal atomic counter incremented on every vertical blank
642 interrupt, and can make their enable and disable vblank 667 interrupt (and then treat the enable_vblank() and disable_vblank()
643 functions into no-ops. 668 callbacks as no-ops).
644 </para> 669 </para>
645 </sect1> 670 </sect1>
646 671
647 <sect1> 672 <sect1>
648 <title>Memory management</title> 673 <title>Memory management</title>
649 <para> 674 <para>
650 The memory manager lies at the heart of many DRM operations, and 675 The memory manager lies at the heart of many DRM operations; it
651 is also required to support advanced client features like OpenGL 676 is required to support advanced client features like OpenGL
652 pbuffers. The DRM currently contains two memory managers, TTM 677 pbuffers. The DRM currently contains two memory managers: TTM
653 and GEM. 678 and GEM.
654 </para> 679 </para>
655 680
@@ -679,41 +704,46 @@ void intel_crt_init(struct drm_device *dev)
679 <para> 704 <para>
680 GEM-enabled drivers must provide gem_init_object() and 705 GEM-enabled drivers must provide gem_init_object() and
681 gem_free_object() callbacks to support the core memory 706 gem_free_object() callbacks to support the core memory
682 allocation routines. They should also provide several driver 707 allocation routines. They should also provide several driver-specific
683 specific ioctls to support command execution, pinning, buffer 708 ioctls to support command execution, pinning, buffer
684 read &amp; write, mapping, and domain ownership transfers. 709 read &amp; write, mapping, and domain ownership transfers.
685 </para> 710 </para>
686 <para> 711 <para>
687 On a fundamental level, GEM involves several operations: memory 712 On a fundamental level, GEM involves several operations:
688 allocation and freeing, command execution, and aperture management 713 <itemizedlist>
689 at command execution time. Buffer object allocation is relatively 714 <listitem>Memory allocation and freeing</listitem>
715 <listitem>Command execution</listitem>
716 <listitem>Aperture management at command execution time</listitem>
717 </itemizedlist>
718 Buffer object allocation is relatively
690 straightforward and largely provided by Linux's shmem layer, which 719 straightforward and largely provided by Linux's shmem layer, which
691 provides memory to back each object. When mapped into the GTT 720 provides memory to back each object. When mapped into the GTT
692 or used in a command buffer, the backing pages for an object are 721 or used in a command buffer, the backing pages for an object are
693 flushed to memory and marked write combined so as to be coherent 722 flushed to memory and marked write combined so as to be coherent
694 with the GPU. Likewise, when the GPU finishes rendering to an object, 723 with the GPU. Likewise, if the CPU accesses an object after the GPU
695 if the CPU accesses it, it must be made coherent with the CPU's view 724 has finished rendering to the object, then the object must be made
725 coherent with the CPU's view
696 of memory, usually involving GPU cache flushing of various kinds. 726 of memory, usually involving GPU cache flushing of various kinds.
697 This core CPU&lt;-&gt;GPU coherency management is provided by the GEM 727 This core CPU&lt;-&gt;GPU coherency management is provided by a
698 set domain function, which evaluates an object's current domain and 728 device-specific ioctl, which evaluates an object's current domain and
699 performs any necessary flushing or synchronization to put the object 729 performs any necessary flushing or synchronization to put the object
700 into the desired coherency domain (note that the object may be busy, 730 into the desired coherency domain (note that the object may be busy,
701 i.e. an active render target; in that case the set domain function 731 i.e. an active render target; in that case, setting the domain
702 will block the client and wait for rendering to complete before 732 blocks the client and waits for rendering to complete before
703 performing any necessary flushing operations). 733 performing any necessary flushing operations).
704 </para> 734 </para>
705 <para> 735 <para>
706 Perhaps the most important GEM function is providing a command 736 Perhaps the most important GEM function is providing a command
707 execution interface to clients. Client programs construct command 737 execution interface to clients. Client programs construct command
708 buffers containing references to previously allocated memory objects 738 buffers containing references to previously allocated memory objects,
709 and submit them to GEM. At that point, GEM will take care to bind 739 and then submit them to GEM. At that point, GEM takes care to bind
710 all the objects into the GTT, execute the buffer, and provide 740 all the objects into the GTT, execute the buffer, and provide
711 necessary synchronization between clients accessing the same buffers. 741 necessary synchronization between clients accessing the same buffers.
712 This often involves evicting some objects from the GTT and re-binding 742 This often involves evicting some objects from the GTT and re-binding
713 others (a fairly expensive operation), and providing relocation 743 others (a fairly expensive operation), and providing relocation
714 support which hides fixed GTT offsets from clients. Clients must 744 support which hides fixed GTT offsets from clients. Clients must
715 take care not to submit command buffers that reference more objects 745 take care not to submit command buffers that reference more objects
716 than can fit in the GTT or GEM will reject them and no rendering 746 than can fit in the GTT; otherwise, GEM will reject them and no rendering
717 will occur. Similarly, if several objects in the buffer require 747 will occur. Similarly, if several objects in the buffer require
718 fence registers to be allocated for correct rendering (e.g. 2D blits 748 fence registers to be allocated for correct rendering (e.g. 2D blits
719 on pre-965 chips), care must be taken not to require more fence 749 on pre-965 chips), care must be taken not to require more fence
@@ -729,7 +759,7 @@ void intel_crt_init(struct drm_device *dev)
729 <title>Output management</title> 759 <title>Output management</title>
730 <para> 760 <para>
731 At the core of the DRM output management code is a set of 761 At the core of the DRM output management code is a set of
732 structures representing CRTCs, encoders and connectors. 762 structures representing CRTCs, encoders, and connectors.
733 </para> 763 </para>
734 <para> 764 <para>
735 A CRTC is an abstraction representing a part of the chip that 765 A CRTC is an abstraction representing a part of the chip that
@@ -765,21 +795,19 @@ void intel_crt_init(struct drm_device *dev)
765 <sect1> 795 <sect1>
766 <title>Framebuffer management</title> 796 <title>Framebuffer management</title>
767 <para> 797 <para>
768 In order to set a mode on a given CRTC, encoder and connector 798 Clients need to provide a framebuffer object which provides a source
769 configuration, clients need to provide a framebuffer object which 799 of pixels for a CRTC to deliver to the encoder(s) and ultimately the
770 will provide a source of pixels for the CRTC to deliver to the encoder(s) 800 connector(s). A framebuffer is fundamentally a driver-specific memory
771 and ultimately the connector(s) in the configuration. A framebuffer 801 object, made into an opaque handle by the DRM's addfb() function.
772 is fundamentally a driver specific memory object, made into an opaque 802 Once a framebuffer has been created this way, it may be passed to the
773 handle by the DRM addfb function. Once an fb has been created this 803 KMS mode setting routines for use in a completed configuration.
774 way it can be passed to the KMS mode setting routines for use in
775 a configuration.
776 </para> 804 </para>
777 </sect1> 805 </sect1>
778 806
779 <sect1> 807 <sect1>
780 <title>Command submission &amp; fencing</title> 808 <title>Command submission &amp; fencing</title>
781 <para> 809 <para>
782 This should cover a few device specific command submission 810 This should cover a few device-specific command submission
783 implementations. 811 implementations.
784 </para> 812 </para>
785 </sect1> 813 </sect1>
@@ -789,7 +817,7 @@ void intel_crt_init(struct drm_device *dev)
789 <para> 817 <para>
790 The DRM core provides some suspend/resume code, but drivers 818 The DRM core provides some suspend/resume code, but drivers
791 wanting full suspend/resume support should provide save() and 819 wanting full suspend/resume support should provide save() and
792 restore() functions. These will be called at suspend, 820 restore() functions. These are called at suspend,
793 hibernate, or resume time, and should perform any state save or 821 hibernate, or resume time, and should perform any state save or
794 restore required by your device across suspend or hibernate 822 restore required by your device across suspend or hibernate
795 states. 823 states.
@@ -812,8 +840,8 @@ void intel_crt_init(struct drm_device *dev)
812 <para> 840 <para>
813 The DRM core exports several interfaces to applications, 841 The DRM core exports several interfaces to applications,
814 generally intended to be used through corresponding libdrm 842 generally intended to be used through corresponding libdrm
815 wrapper functions. In addition, drivers export device specific 843 wrapper functions. In addition, drivers export device-specific
816 interfaces for use by userspace drivers &amp; device aware 844 interfaces for use by userspace drivers &amp; device-aware
817 applications through ioctls and sysfs files. 845 applications through ioctls and sysfs files.
818 </para> 846 </para>
819 <para> 847 <para>
@@ -822,8 +850,8 @@ void intel_crt_init(struct drm_device *dev)
822 management, memory management, and output management. 850 management, memory management, and output management.
823 </para> 851 </para>
824 <para> 852 <para>
825 Cover generic ioctls and sysfs layout here. Only need high 853 Cover generic ioctls and sysfs layout here. We only need high-level
826 level info, since man pages will cover the rest. 854 info, since man pages should cover the rest.
827 </para> 855 </para>
828 </chapter> 856 </chapter>
829 857