1.. _todo: 2 3========= 4TODO list 5========= 6 7This section contains a list of smaller janitorial tasks in the kernel DRM 8graphics subsystem useful as newbie projects. Or for slow rainy days. 9 10Difficulty 11---------- 12 13To make it easier task are categorized into different levels: 14 15Starter: Good tasks to get started with the DRM subsystem. 16 17Intermediate: Tasks which need some experience with working in the DRM 18subsystem, or some specific GPU/display graphics knowledge. For debugging issue 19it's good to have the relevant hardware (or a virtual driver set up) available 20for testing. 21 22Advanced: Tricky tasks that need fairly good understanding of the DRM subsystem 23and graphics topics. Generally need the relevant hardware for development and 24testing. 25 26Expert: Only attempt these if you've successfully completed some tricky 27refactorings already and are an expert in the specific area 28 29Subsystem-wide refactorings 30=========================== 31 32Remove custom dumb_map_offset implementations 33--------------------------------------------- 34 35All GEM based drivers should be using drm_gem_create_mmap_offset() instead. 36Audit each individual driver, make sure it'll work with the generic 37implementation (there's lots of outdated locking leftovers in various 38implementations), and then remove it. 39 40Contact: Daniel Vetter, respective driver maintainers 41 42Level: Intermediate 43 44Convert existing KMS drivers to atomic modesetting 45-------------------------------------------------- 46 473.19 has the atomic modeset interfaces and helpers, so drivers can now be 48converted over. Modern compositors like Wayland or Surfaceflinger on Android 49really want an atomic modeset interface, so this is all about the bright 50future. 51 52There is a conversion guide for atomic and all you need is a GPU for a 53non-converted driver (again virtual HW drivers for KVM are still all 54suitable). 55 56As part of this drivers also need to convert to universal plane (which means 57exposing primary & cursor as proper plane objects). But that's much easier to 58do by directly using the new atomic helper driver callbacks. 59 60Contact: Daniel Vetter, respective driver maintainers 61 62Level: Advanced 63 64Clean up the clipped coordination confusion around planes 65--------------------------------------------------------- 66 67We have a helper to get this right with drm_plane_helper_check_update(), but 68it's not consistently used. This should be fixed, preferrably in the atomic 69helpers (and drivers then moved over to clipped coordinates). Probably the 70helper should also be moved from drm_plane_helper.c to the atomic helpers, to 71avoid confusion - the other helpers in that file are all deprecated legacy 72helpers. 73 74Contact: Ville Syrjälä, Daniel Vetter, driver maintainers 75 76Level: Advanced 77 78Improve plane atomic_check helpers 79---------------------------------- 80 81Aside from the clipped coordinates right above there's a few suboptimal things 82with the current helpers: 83 84- drm_plane_helper_funcs->atomic_check gets called for enabled or disabled 85 planes. At best this seems to confuse drivers, worst it means they blow up 86 when the plane is disabled without the CRTC. The only special handling is 87 resetting values in the plane state structures, which instead should be moved 88 into the drm_plane_funcs->atomic_duplicate_state functions. 89 90- Once that's done, helpers could stop calling ->atomic_check for disabled 91 planes. 92 93- Then we could go through all the drivers and remove the more-or-less confused 94 checks for plane_state->fb and plane_state->crtc. 95 96Contact: Daniel Vetter 97 98Level: Advanced 99 100Convert early atomic drivers to async commit helpers 101---------------------------------------------------- 102 103For the first year the atomic modeset helpers didn't support asynchronous / 104nonblocking commits, and every driver had to hand-roll them. This is fixed 105now, but there's still a pile of existing drivers that easily could be 106converted over to the new infrastructure. 107 108One issue with the helpers is that they require that drivers handle completion 109events for atomic commits correctly. But fixing these bugs is good anyway. 110 111Somewhat related is the legacy_cursor_update hack, which should be replaced with 112the new atomic_async_check/commit functionality in the helpers in drivers that 113still look at that flag. 114 115Contact: Daniel Vetter, respective driver maintainers 116 117Level: Advanced 118 119Fallout from atomic KMS 120----------------------- 121 122``drm_atomic_helper.c`` provides a batch of functions which implement legacy 123IOCTLs on top of the new atomic driver interface. Which is really nice for 124gradual conversion of drivers, but unfortunately the semantic mismatches are 125a bit too severe. So there's some follow-up work to adjust the function 126interfaces to fix these issues: 127 128* atomic needs the lock acquire context. At the moment that's passed around 129 implicitly with some horrible hacks, and it's also allocate with 130 ``GFP_NOFAIL`` behind the scenes. All legacy paths need to start allocating 131 the acquire context explicitly on stack and then also pass it down into 132 drivers explicitly so that the legacy-on-atomic functions can use them. 133 134 Except for some driver code this is done. This task should be finished by 135 adding WARN_ON(!drm_drv_uses_atomic_modeset) in drm_modeset_lock_all(). 136 137* A bunch of the vtable hooks are now in the wrong place: DRM has a split 138 between core vfunc tables (named ``drm_foo_funcs``), which are used to 139 implement the userspace ABI. And then there's the optional hooks for the 140 helper libraries (name ``drm_foo_helper_funcs``), which are purely for 141 internal use. Some of these hooks should be move from ``_funcs`` to 142 ``_helper_funcs`` since they are not part of the core ABI. There's a 143 ``FIXME`` comment in the kerneldoc for each such case in ``drm_crtc.h``. 144 145Contact: Daniel Vetter 146 147Level: Intermediate 148 149Get rid of dev->struct_mutex from GEM drivers 150--------------------------------------------- 151 152``dev->struct_mutex`` is the Big DRM Lock from legacy days and infested 153everything. Nowadays in modern drivers the only bit where it's mandatory is 154serializing GEM buffer object destruction. Which unfortunately means drivers 155have to keep track of that lock and either call ``unreference`` or 156``unreference_locked`` depending upon context. 157 158Core GEM doesn't have a need for ``struct_mutex`` any more since kernel 4.8, 159and there's a GEM object ``free`` callback for any drivers which are 160entirely ``struct_mutex`` free. 161 162For drivers that need ``struct_mutex`` it should be replaced with a driver- 163private lock. The tricky part is the BO free functions, since those can't 164reliably take that lock any more. Instead state needs to be protected with 165suitable subordinate locks or some cleanup work pushed to a worker thread. For 166performance-critical drivers it might also be better to go with a more 167fine-grained per-buffer object and per-context lockings scheme. Currently only 168the ``msm`` and `i915` drivers use ``struct_mutex``. 169 170Contact: Daniel Vetter, respective driver maintainers 171 172Level: Advanced 173 174Move Buffer Object Locking to dma_resv_lock() 175--------------------------------------------- 176 177Many drivers have their own per-object locking scheme, usually using 178mutex_lock(). This causes all kinds of trouble for buffer sharing, since 179depending which driver is the exporter and importer, the locking hierarchy is 180reversed. 181 182To solve this we need one standard per-object locking mechanism, which is 183dma_resv_lock(). This lock needs to be called as the outermost lock, with all 184other driver specific per-object locks removed. The problem is tha rolling out 185the actual change to the locking contract is a flag day, due to struct dma_buf 186buffer sharing. 187 188Level: Expert 189 190Convert logging to drm_* functions with drm_device paramater 191------------------------------------------------------------ 192 193For drivers which could have multiple instances, it is necessary to 194differentiate between which is which in the logs. Since DRM_INFO/WARN/ERROR 195don't do this, drivers used dev_info/warn/err to make this differentiation. We 196now have drm_* variants of the drm print functions, so we can start to convert 197those drivers back to using drm-formatted specific log messages. 198 199Before you start this conversion please contact the relevant maintainers to make 200sure your work will be merged - not everyone agrees that the DRM dmesg macros 201are better. 202 203Contact: Sean Paul, Maintainer of the driver you plan to convert 204 205Level: Starter 206 207Convert drivers to use simple modeset suspend/resume 208---------------------------------------------------- 209 210Most drivers (except i915 and nouveau) that use 211drm_atomic_helper_suspend/resume() can probably be converted to use 212drm_mode_config_helper_suspend/resume(). Also there's still open-coded version 213of the atomic suspend/resume code in older atomic modeset drivers. 214 215Contact: Maintainer of the driver you plan to convert 216 217Level: Intermediate 218 219Convert drivers to use drm_fbdev_generic_setup() 220------------------------------------------------ 221 222Most drivers can use drm_fbdev_generic_setup(). Driver have to implement 223atomic modesetting and GEM vmap support. Historically, generic fbdev emulation 224expected the framebuffer in system memory or system-like memory. By employing 225struct dma_buf_map, drivers with frambuffers in I/O memory can be supported 226as well. 227 228Contact: Maintainer of the driver you plan to convert 229 230Level: Intermediate 231 232Reimplement functions in drm_fbdev_fb_ops without fbdev 233------------------------------------------------------- 234 235A number of callback functions in drm_fbdev_fb_ops could benefit from 236being rewritten without dependencies on the fbdev module. Some of the 237helpers could further benefit from using struct dma_buf_map instead of 238raw pointers. 239 240Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter 241 242Level: Advanced 243 244 245drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup 246----------------------------------------------------------------- 247 248A lot more drivers could be switched over to the drm_gem_framebuffer helpers. 249Various hold-ups: 250 251- Need to switch over to the generic dirty tracking code using 252 drm_atomic_helper_dirtyfb first (e.g. qxl). 253 254- Need to switch to drm_fbdev_generic_setup(), otherwise a lot of the custom fb 255 setup code can't be deleted. 256 257- Many drivers wrap drm_gem_fb_create() only to check for valid formats. For 258 atomic drivers we could check for valid formats by calling 259 drm_plane_check_pixel_format() against all planes, and pass if any plane 260 supports the format. For non-atomic that's not possible since like the format 261 list for the primary plane is fake and we'd therefor reject valid formats. 262 263- Many drivers subclass drm_framebuffer, we'd need a embedding compatible 264 version of the varios drm_gem_fb_create functions. Maybe called 265 drm_gem_fb_create/_with_dirty/_with_funcs as needed. 266 267Contact: Daniel Vetter 268 269Level: Intermediate 270 271Clean up mmap forwarding 272------------------------ 273 274A lot of drivers forward gem mmap calls to dma-buf mmap for imported buffers. 275And also a lot of them forward dma-buf mmap to the gem mmap implementations. 276There's drm_gem_prime_mmap() for this now, but still needs to be rolled out. 277 278Contact: Daniel Vetter 279 280Level: Intermediate 281 282Generic fbdev defio support 283--------------------------- 284 285The defio support code in the fbdev core has some very specific requirements, 286which means drivers need to have a special framebuffer for fbdev. The main 287issue is that it uses some fields in struct page itself, which breaks shmem 288gem objects (and other things). To support defio, affected drivers require 289the use of a shadow buffer, which may add CPU and memory overhead. 290 291Possible solution would be to write our own defio mmap code in the drm fbdev 292emulation. It would need to fully wrap the existing mmap ops, forwarding 293everything after it has done the write-protect/mkwrite trickery: 294 295- In the drm_fbdev_fb_mmap helper, if we need defio, change the 296 default page prots to write-protected with something like this:: 297 298 vma->vm_page_prot = pgprot_wrprotect(vma->vm_page_prot); 299 300- Set the mkwrite and fsync callbacks with similar implementions to the core 301 fbdev defio stuff. These should all work on plain ptes, they don't actually 302 require a struct page. uff. These should all work on plain ptes, they don't 303 actually require a struct page. 304 305- Track the dirty pages in a separate structure (bitfield with one bit per page 306 should work) to avoid clobbering struct page. 307 308Might be good to also have some igt testcases for this. 309 310Contact: Daniel Vetter, Noralf Tronnes 311 312Level: Advanced 313 314Garbage collect fbdev scrolling acceleration 315-------------------------------------------- 316 317Scroll acceleration is disabled in fbcon by hard-wiring p->scrollmode = 318SCROLL_REDRAW. There's a ton of code this will allow us to remove: 319 320- lots of code in fbcon.c 321 322- a bunch of the hooks in fbcon_ops, maybe the remaining hooks could be called 323 directly instead of the function table (with a switch on p->rotate) 324 325- fb_copyarea is unused after this, and can be deleted from all drivers 326 327Note that not all acceleration code can be deleted, since clearing and cursor 328support is still accelerated, which might be good candidates for further 329deletion projects. 330 331Contact: Daniel Vetter 332 333Level: Intermediate 334 335idr_init_base() 336--------------- 337 338DRM core&drivers uses a lot of idr (integer lookup directories) for mapping 339userspace IDs to internal objects, and in most places ID=0 means NULL and hence 340is never used. Switching to idr_init_base() for these would make the idr more 341efficient. 342 343Contact: Daniel Vetter 344 345Level: Starter 346 347struct drm_gem_object_funcs 348--------------------------- 349 350GEM objects can now have a function table instead of having the callbacks on the 351DRM driver struct. This is now the preferred way. Callbacks in drivers have been 352converted, except for struct drm_driver.gem_prime_mmap. 353 354Level: Intermediate 355 356Use DRM_MODESET_LOCK_ALL_* helpers instead of boilerplate 357--------------------------------------------------------- 358 359For cases where drivers are attempting to grab the modeset locks with a local 360acquire context. Replace the boilerplate code surrounding 361drm_modeset_lock_all_ctx() with DRM_MODESET_LOCK_ALL_BEGIN() and 362DRM_MODESET_LOCK_ALL_END() instead. 363 364This should also be done for all places where drm_modeset_lock_all() is still 365used. 366 367As a reference, take a look at the conversions already completed in drm core. 368 369Contact: Sean Paul, respective driver maintainers 370 371Level: Starter 372 373Rename CMA helpers to DMA helpers 374--------------------------------- 375 376CMA (standing for contiguous memory allocator) is really a bit an accident of 377what these were used for first, a much better name would be DMA helpers. In the 378text these should even be called coherent DMA memory helpers (so maybe CDM, but 379no one knows what that means) since underneath they just use dma_alloc_coherent. 380 381Contact: Laurent Pinchart, Daniel Vetter 382 383Level: Intermediate (mostly because it is a huge tasks without good partial 384milestones, not technically itself that challenging) 385 386connector register/unregister fixes 387----------------------------------- 388 389- For most connectors it's a no-op to call drm_connector_register/unregister 390 directly from driver code, drm_dev_register/unregister take care of this 391 already. We can remove all of them. 392 393- For dp drivers it's a bit more a mess, since we need the connector to be 394 registered when calling drm_dp_aux_register. Fix this by instead calling 395 drm_dp_aux_init, and moving the actual registering into a late_register 396 callback as recommended in the kerneldoc. 397 398Level: Intermediate 399 400Remove load/unload callbacks from all non-DRIVER_LEGACY drivers 401--------------------------------------------------------------- 402 403The load/unload callbacks in struct &drm_driver are very much midlayers, plus 404for historical reasons they get the ordering wrong (and we can't fix that) 405between setting up the &drm_driver structure and calling drm_dev_register(). 406 407- Rework drivers to no longer use the load/unload callbacks, directly coding the 408 load/unload sequence into the driver's probe function. 409 410- Once all non-DRIVER_LEGACY drivers are converted, disallow the load/unload 411 callbacks for all modern drivers. 412 413Contact: Daniel Vetter 414 415Level: Intermediate 416 417Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi 418--------------------------------------------------------------- 419 420Once EDID is parsed, the monitor HDMI support information is available through 421drm_display_info.is_hdmi. Many drivers still call drm_detect_hdmi_monitor() to 422retrieve the same information, which is less efficient. 423 424Audit each individual driver calling drm_detect_hdmi_monitor() and switch to 425drm_display_info.is_hdmi if applicable. 426 427Contact: Laurent Pinchart, respective driver maintainers 428 429Level: Intermediate 430 431Consolidate custom driver modeset properties 432-------------------------------------------- 433 434Before atomic modeset took place, many drivers where creating their own 435properties. Among other things, atomic brought the requirement that custom, 436driver specific properties should not be used. 437 438For this task, we aim to introduce core helpers or reuse the existing ones 439if available: 440 441A quick, unconfirmed, examples list. 442 443Introduce core helpers: 444- audio (amdgpu, intel, gma500, radeon) 445- brightness, contrast, etc (armada, nouveau) - overlay only (?) 446- broadcast rgb (gma500, intel) 447- colorkey (armada, nouveau, rcar) - overlay only (?) 448- dither (amdgpu, nouveau, radeon) - varies across drivers 449- underscan family (amdgpu, radeon, nouveau) 450 451Already in core: 452- colorspace (sti) 453- tv format names, enhancements (gma500, intel) 454- tv overscan, margins, etc. (gma500, intel) 455- zorder (omapdrm) - same as zpos (?) 456 457 458Contact: Emil Velikov, respective driver maintainers 459 460Level: Intermediate 461 462Plumb drm_atomic_state all over 463------------------------------- 464 465Currently various atomic functions take just a single or a handful of 466object states (eg. plane state). While that single object state can 467suffice for some simple cases, we often have to dig out additional 468object states for dealing with various dependencies between the individual 469objects or the hardware they represent. The process of digging out the 470additional states is rather non-intuitive and error prone. 471 472To fix that most functions should rather take the overall 473drm_atomic_state as one of their parameters. The other parameters 474would generally be the object(s) we mainly want to interact with. 475 476For example, instead of 477 478.. code-block:: c 479 480 int (*atomic_check)(struct drm_plane *plane, struct drm_plane_state *state); 481 482we would have something like 483 484.. code-block:: c 485 486 int (*atomic_check)(struct drm_plane *plane, struct drm_atomic_state *state); 487 488The implementation can then trivially gain access to any required object 489state(s) via drm_atomic_get_plane_state(), drm_atomic_get_new_plane_state(), 490drm_atomic_get_old_plane_state(), and their equivalents for 491other object types. 492 493Additionally many drivers currently access the object->state pointer 494directly in their commit functions. That is not going to work if we 495eg. want to allow deeper commit pipelines as those pointers could 496then point to the states corresponding to a future commit instead of 497the current commit we're trying to process. Also non-blocking commits 498execute locklessly so there are serious concerns with dereferencing 499the object->state pointers without holding the locks that protect them. 500Use of drm_atomic_get_new_plane_state(), drm_atomic_get_old_plane_state(), 501etc. avoids these problems as well since they relate to a specific 502commit via the passed in drm_atomic_state. 503 504Contact: Ville Syrjälä, Daniel Vetter 505 506Level: Intermediate 507 508Use struct dma_buf_map throughout codebase 509------------------------------------------ 510 511Pointers to shared device memory are stored in struct dma_buf_map. Each 512instance knows whether it refers to system or I/O memory. Most of the DRM-wide 513interface have been converted to use struct dma_buf_map, but implementations 514often still use raw pointers. 515 516The task is to use struct dma_buf_map where it makes sense. 517 518* Memory managers should use struct dma_buf_map for dma-buf-imported buffers. 519* TTM might benefit from using struct dma_buf_map internally. 520* Framebuffer copying and blitting helpers should operate on struct dma_buf_map. 521 522Contact: Thomas Zimmermann <tzimmermann@suse.de>, Christian König, Daniel Vetter 523 524Level: Intermediate 525 526 527Core refactorings 528================= 529 530Make panic handling work 531------------------------ 532 533This is a really varied tasks with lots of little bits and pieces: 534 535* The panic path can't be tested currently, leading to constant breaking. The 536 main issue here is that panics can be triggered from hardirq contexts and 537 hence all panic related callback can run in hardirq context. It would be 538 awesome if we could test at least the fbdev helper code and driver code by 539 e.g. trigger calls through drm debugfs files. hardirq context could be 540 achieved by using an IPI to the local processor. 541 542* There's a massive confusion of different panic handlers. DRM fbdev emulation 543 helpers have one, but on top of that the fbcon code itself also has one. We 544 need to make sure that they stop fighting over each another. 545 546* ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and 547 isn't a full solution for panic paths. We need to make sure that it only 548 returns true if there's a panic going on for real, and fix up all the 549 fallout. 550 551* The panic handler must never sleep, which also means it can't ever 552 ``mutex_lock()``. Also it can't grab any other lock unconditionally, not 553 even spinlocks (because NMI and hardirq can panic too). We need to either 554 make sure to not call such paths, or trylock everything. Really tricky. 555 556* For the above locking troubles reasons it's pretty much impossible to 557 attempt a synchronous modeset from panic handlers. The only thing we could 558 try to achive is an atomic ``set_base`` of the primary plane, and hope that 559 it shows up. Everything else probably needs to be delayed to some worker or 560 something else which happens later on. Otherwise it just kills the box 561 harder, prevent the panic from going out on e.g. netconsole. 562 563* There's also proposal for a simplied DRM console instead of the full-blown 564 fbcon and DRM fbdev emulation. Any kind of panic handling tricks should 565 obviously work for both console, in case we ever get kmslog merged. 566 567Contact: Daniel Vetter 568 569Level: Advanced 570 571Clean up the debugfs support 572---------------------------- 573 574There's a bunch of issues with it: 575 576- The drm_info_list ->show() function doesn't even bother to cast to the drm 577 structure for you. This is lazy. 578 579- We probably want to have some support for debugfs files on crtc/connectors and 580 maybe other kms objects directly in core. There's even drm_print support in 581 the funcs for these objects to dump kms state, so it's all there. And then the 582 ->show() functions should obviously give you a pointer to the right object. 583 584- The drm_info_list stuff is centered on drm_minor instead of drm_device. For 585 anything we want to print drm_device (or maybe drm_file) is the right thing. 586 587- The drm_driver->debugfs_init hooks we have is just an artifact of the old 588 midlayered load sequence. DRM debugfs should work more like sysfs, where you 589 can create properties/files for an object anytime you want, and the core 590 takes care of publishing/unpuplishing all the files at register/unregister 591 time. Drivers shouldn't need to worry about these technicalities, and fixing 592 this (together with the drm_minor->drm_device move) would allow us to remove 593 debugfs_init. 594 595Contact: Daniel Vetter 596 597Level: Intermediate 598 599KMS cleanups 600------------ 601 602Some of these date from the very introduction of KMS in 2008 ... 603 604- Make ->funcs and ->helper_private vtables optional. There's a bunch of empty 605 function tables in drivers, but before we can remove them we need to make sure 606 that all the users in helpers and drivers do correctly check for a NULL 607 vtable. 608 609- Cleanup up the various ->destroy callbacks. A lot of them just wrapt the 610 drm_*_cleanup implementations and can be removed. Some tack a kfree() at the 611 end, for which we could add drm_*_cleanup_kfree(). And then there's the (for 612 historical reasons) misnamed drm_primary_helper_destroy() function. 613 614Level: Intermediate 615 616Better Testing 617============== 618 619Enable trinity for DRM 620---------------------- 621 622And fix up the fallout. Should be really interesting ... 623 624Level: Advanced 625 626Make KMS tests in i-g-t generic 627------------------------------- 628 629The i915 driver team maintains an extensive testsuite for the i915 DRM driver, 630including tons of testcases for corner-cases in the modesetting API. It would 631be awesome if those tests (at least the ones not relying on Intel-specific GEM 632features) could be made to run on any KMS driver. 633 634Basic work to run i-g-t tests on non-i915 is done, what's now missing is mass- 635converting things over. For modeset tests we also first need a bit of 636infrastructure to use dumb buffers for untiled buffers, to be able to run all 637the non-i915 specific modeset tests. 638 639Level: Advanced 640 641Extend virtual test driver (VKMS) 642--------------------------------- 643 644See the documentation of :ref:`VKMS <vkms>` for more details. This is an ideal 645internship task, since it only requires a virtual machine and can be sized to 646fit the available time. 647 648Contact: Daniel Vetter 649 650Level: See details 651 652Backlight Refactoring 653--------------------- 654 655Backlight drivers have a triple enable/disable state, which is a bit overkill. 656Plan to fix this: 657 6581. Roll out backlight_enable() and backlight_disable() helpers everywhere. This 659 has started already. 6602. In all, only look at one of the three status bits set by the above helpers. 6613. Remove the other two status bits. 662 663Contact: Daniel Vetter 664 665Level: Intermediate 666 667Driver Specific 668=============== 669 670AMD DC Display Driver 671--------------------- 672 673AMD DC is the display driver for AMD devices starting with Vega. There has been 674a bunch of progress cleaning it up but there's still plenty of work to be done. 675 676See drivers/gpu/drm/amd/display/TODO for tasks. 677 678Contact: Harry Wentland, Alex Deucher 679 680Bootsplash 681========== 682 683There is support in place now for writing internal DRM clients making it 684possible to pick up the bootsplash work that was rejected because it was written 685for fbdev. 686 687- [v6,8/8] drm/client: Hack: Add bootsplash example 688 https://patchwork.freedesktop.org/patch/306579/ 689 690- [RFC PATCH v2 00/13] Kernel based bootsplash 691 https://lore.kernel.org/r/20171213194755.3409-1-mstaudt@suse.de 692 693Contact: Sam Ravnborg 694 695Level: Advanced 696 697Outside DRM 698=========== 699 700Convert fbdev drivers to DRM 701---------------------------- 702 703There are plenty of fbdev drivers for older hardware. Some hwardware has 704become obsolete, but some still provides good(-enough) framebuffers. The 705drivers that are still useful should be converted to DRM and afterwards 706removed from fbdev. 707 708Very simple fbdev drivers can best be converted by starting with a new 709DRM driver. Simple KMS helpers and SHMEM should be able to handle any 710existing hardware. The new driver's call-back functions are filled from 711existing fbdev code. 712 713More complex fbdev drivers can be refactored step-by-step into a DRM 714driver with the help of the DRM fbconv helpers. [1] These helpers provide 715the transition layer between the DRM core infrastructure and the fbdev 716driver interface. Create a new DRM driver on top of the fbconv helpers, 717copy over the fbdev driver, and hook it up to the DRM code. Examples for 718several fbdev drivers are available at [1] and a tutorial of this process 719available at [2]. The result is a primitive DRM driver that can run X11 720and Weston. 721 722 - [1] https://gitlab.freedesktop.org/tzimmermann/linux/tree/fbconv 723 - [2] https://gitlab.freedesktop.org/tzimmermann/linux/blob/fbconv/drivers/gpu/drm/drm_fbconv_helper.c 724 725Contact: Thomas Zimmermann <tzimmermann@suse.de> 726 727Level: Advanced 728