Contact: Daniel Vetter, respective driver maintainers
-Better manual-upload support for atomic
----------------------------------------
-
-This would be especially useful for tinydrm:
-
-- Add a struct drm_rect dirty_clip to drm_crtc_state. When duplicating the
- crtc state, clear that to the max values, x/y = 0 and w/h = MAX_INT, in
- __drm_atomic_helper_crtc_duplicate_state().
-
-- Move tinydrm_merge_clips into drm_framebuffer.c, dropping the tinydrm\_
- prefix ofc and using drm_fb\_. drm_framebuffer.c makes sense since this
- is a function useful to implement the fb->dirty function.
-
-- Create a new drm_fb_dirty function which does essentially what e.g.
- mipi_dbi_fb_dirty does. You can use e.g. drm_atomic_helper_update_plane as the
- template. But instead of doing a simple full-screen plane update, this new
- helper also sets crtc_state->dirty_clip to the right coordinates. And of
- course it needs to check whether the fb is actually active (and maybe where),
- so there's some book-keeping involved. There's also some good fun involved in
- scaling things appropriately. For that case we might simply give up and
- declare the entire area covered by the plane as dirty.
-
-Contact: Noralf Trønnes, Daniel Vetter
-
Fallout from atomic KMS
-----------------------
Contact: Daniel Vetter
+Generic fbdev defio support
+---------------------------
+
+The defio support code in the fbdev core has some very specific requirements,
+which means drivers need to have a special framebuffer for fbdev. Which prevents
+us from using the generic fbdev emulation code everywhere. The main issue is
+that it uses some fields in struct page itself, which breaks shmem gem objects
+(and other things).
+
+Possible solution would be to write our own defio mmap code in the drm fbdev
+emulation. It would need to fully wrap the existing mmap ops, forwarding
+everything after it has done the write-protect/mkwrite trickery:
+
+- In the drm_fbdev_fb_mmap helper, if we need defio, change the
+ default page prots to write-protected with something like this::
+
+ vma->vm_page_prot = pgprot_wrprotect(vma->vm_page_prot);
+
+- Set the mkwrite and fsync callbacks with similar implementions to the core
+ fbdev defio stuff. These should all work on plain ptes, they don't actually
+ require a struct page. uff. These should all work on plain ptes, they don't
+ actually require a struct page.
+
+- Track the dirty pages in a separate structure (bitfield with one bit per page
+ should work) to avoid clobbering struct page.
+
+Might be good to also have some igt testcases for this.
+
+Contact: Daniel Vetter, Noralf Tronnes
+
Put a reservation_object into drm_gem_object
--------------------------------------------
Contact: Sean Paul, respective driver maintainers
+Rename CMA helpers to DMA helpers
+---------------------------------
+
+CMA (standing for contiguous memory allocator) is really a bit an accident of
+what these were used for first, a much better name would be DMA helpers. In the
+text these should even be called coherent DMA memory helpers (so maybe CDM, but
+no one knows what that means) since underneath they just use dma_alloc_coherent.
+
+Contact: Laurent Pinchart, Daniel Vetter
+
+Convert direct mode.vrefresh accesses to use drm_mode_vrefresh()
+----------------------------------------------------------------
+
+drm_display_mode.vrefresh isn't guaranteed to be populated. As such, using it
+is risky and has been known to cause div-by-zero bugs. Fortunately, drm core
+has helper which will use mode.vrefresh if it's !0 and will calculate it from
+the timings when it's 0.
+
+Use simple search/replace, or (more fun) cocci to replace instances of direct
+vrefresh access with a call to the helper. Check out
+https://lists.freedesktop.org/archives/dri-devel/2019-January/205186.html for
+inspiration.
+
+Once all instances of vrefresh have been converted, remove vrefresh from
+drm_display_mode to avoid future use.
+
+Contact: Sean Paul
+
+Remove drm_display_mode.hsync
+-----------------------------
+
+We have drm_mode_hsync() to calculate this from hsync_start/end, since drivers
+shouldn't/don't use this, remove this member to avoid any temptations to use it
+in the future. If there is any debug code using drm_display_mode.hsync, convert
+it to use drm_mode_hsync() instead.
+
+Contact: Sean Paul
+
Core refactorings
=================
Some of these date from the very introduction of KMS in 2008 ...
-- drm_mode_config.crtc_idr is misnamed, since it contains all KMS object. Should
- be renamed to drm_mode_config.object_idr.
-
- drm_display_mode doesn't need to be derived from drm_mode_object. That's
leftovers from older (never merged into upstream) KMS designs where modes
where set using their ID, including support to add/remove modes.
one of the ideas for having a shared dsi/dbi helper, abstracting away the
transport details more.
-- tinydrm_gem_cma_prime_import_sg_table should probably go into the cma
- helpers, as a _vmapped variant (since not every driver needs the vmap).
- And tinydrm_gem_cma_free_object could the be merged into
- drm_gem_cma_free_object().
-
-- tinydrm_fb_create we could move into drm_simple_pipe, only need to add
- the fb_create hook to drm_simple_pipe_funcs, which would again simplify a
- bunch of things (since it gives you a one-stop vfunc for simple drivers).
-
- Quick aside: The unregister devm stuff is kinda getting the lifetimes of
a drm_device wrong. Doesn't matter, since everyone else gets it wrong
too :-)
-- also rework the drm_framebuffer_funcs->dirty hook wire-up, see above.
-
Contact: Noralf Trønnes, Daniel Vetter
AMD DC Display Driver
projects / linux-2.6-block.git / blobdiff