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authorDave Airlie <airlied@redhat.com>2021-03-16 16:45:12 +1000
committerDave Airlie <airlied@redhat.com>2021-03-16 17:08:46 +1000
commit51c3b916a4d7e24b4918925965867fdd9bd8dd59 (patch)
tree3257e3e0fda7fbb0fe1425177b0c661db1bfee63 /Documentation/gpu/todo.rst
parent1e28eed17697bcf343c6743f0028cc3b5dd88bf0 (diff)
parent762949bb1da78941b25e63f7e952af037eee15a9 (diff)
downloadlinux-51c3b916a4d7e24b4918925965867fdd9bd8dd59.tar.gz
Merge tag 'drm-misc-next-2021-03-03' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
drm-misc-next for 5.13: UAPI Changes: Cross-subsystem Changes: Core Changes: - %p4cc printk format modifier - atomic: introduce drm_crtc_commit_wait, rework atomic plane state helpers to take the drm_commit_state structure - dma-buf: heaps rework to return a struct dma_buf - simple-kms: Add plate state helpers - ttm: debugfs support, removal of sysfs Driver Changes: - Convert drivers to shadow plane helpers - arc: Move to drm/tiny - ast: cursor plane reworks - gma500: Remove TTM and medfield support - mxsfb: imx8mm support - panfrost: MMU IRQ handling rework - qxl: rework to better handle resources deallocation, locking - sun4i: Add alpha properties for UI and VI layers - vc4: RPi4 CEC support - vmwgfx: doc cleanup Signed-off-by: Dave Airlie <airlied@redhat.com> From: Maxime Ripard <maxime@cerno.tech> Link: https://patchwork.freedesktop.org/patch/msgid/20210303100600.dgnkadonzuvfnu22@gilmour
Diffstat (limited to 'Documentation/gpu/todo.rst')
-rw-r--r--Documentation/gpu/todo.rst74
1 files changed, 15 insertions, 59 deletions
diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 22ce801e3a8d..1b4b64b71c7e 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -459,52 +459,6 @@ Contact: Emil Velikov, respective driver maintainers
Level: Intermediate
-Plumb drm_atomic_state all over
--------------------------------
-
-Currently various atomic functions take just a single or a handful of
-object states (eg. plane state). While that single object state can
-suffice for some simple cases, we often have to dig out additional
-object states for dealing with various dependencies between the individual
-objects or the hardware they represent. The process of digging out the
-additional states is rather non-intuitive and error prone.
-
-To fix that most functions should rather take the overall
-drm_atomic_state as one of their parameters. The other parameters
-would generally be the object(s) we mainly want to interact with.
-
-For example, instead of
-
-.. code-block:: c
-
- int (*atomic_check)(struct drm_plane *plane, struct drm_plane_state *state);
-
-we would have something like
-
-.. code-block:: c
-
- int (*atomic_check)(struct drm_plane *plane, struct drm_atomic_state *state);
-
-The implementation can then trivially gain access to any required object
-state(s) via drm_atomic_get_plane_state(), drm_atomic_get_new_plane_state(),
-drm_atomic_get_old_plane_state(), and their equivalents for
-other object types.
-
-Additionally many drivers currently access the object->state pointer
-directly in their commit functions. That is not going to work if we
-eg. want to allow deeper commit pipelines as those pointers could
-then point to the states corresponding to a future commit instead of
-the current commit we're trying to process. Also non-blocking commits
-execute locklessly so there are serious concerns with dereferencing
-the object->state pointers without holding the locks that protect them.
-Use of drm_atomic_get_new_plane_state(), drm_atomic_get_old_plane_state(),
-etc. avoids these problems as well since they relate to a specific
-commit via the passed in drm_atomic_state.
-
-Contact: Ville Syrjälä, Daniel Vetter
-
-Level: Intermediate
-
Use struct dma_buf_map throughout codebase
------------------------------------------
@@ -596,20 +550,24 @@ Contact: Daniel Vetter
Level: Intermediate
-KMS cleanups
-------------
+Object lifetime fixes
+---------------------
+
+There's two related issues here
+
+- Cleanup up the various ->destroy callbacks, which often are all the same
+ simple code.
-Some of these date from the very introduction of KMS in 2008 ...
+- Lots of drivers erroneously allocate DRM modeset objects using devm_kzalloc,
+ which results in use-after free issues on driver unload. This can be serious
+ trouble even for drivers for hardware integrated on the SoC due to
+ EPROBE_DEFERRED backoff.
-- Make ->funcs and ->helper_private vtables optional. There's a bunch of empty
- function tables in drivers, but before we can remove them we need to make sure
- that all the users in helpers and drivers do correctly check for a NULL
- vtable.
+Both these problems can be solved by switching over to drmm_kzalloc(), and the
+various convenience wrappers provided, e.g. drmm_crtc_alloc_with_planes(),
+drmm_universal_plane_alloc(), ... and so on.
-- Cleanup up the various ->destroy callbacks. A lot of them just wrapt the
- drm_*_cleanup implementations and can be removed. Some tack a kfree() at the
- end, for which we could add drm_*_cleanup_kfree(). And then there's the (for
- historical reasons) misnamed drm_primary_helper_destroy() function.
+Contact: Daniel Vetter
Level: Intermediate
@@ -666,8 +624,6 @@ See the documentation of :ref:`VKMS <vkms>` for more details. This is an ideal
internship task, since it only requires a virtual machine and can be sized to
fit the available time.
-Contact: Daniel Vetter
-
Level: See details
Backlight Refactoring