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drm/todo: Remove the drm_atomic_state todo item 

Only planes' prepare_fb and cleanup_fb, and encoders' atomic_check and
atomic_mode_set hooks remain with an object state and not the global
drm_atomic_state.

prepare_fb and cleanup_fb operate by design on a given state and
depending on the calling site can operate on either the old or new
state, so it doesn't really make much sense to convert them.

The encoders' atomic_check and atomic_mode_set operate on the CRTC and
connector state connected to them since encoders don't have a state of
their own. Without those state pointers, we would need to get the CRTC
through the drm_connector_state crtc pointer.

However, in order to get the drm_connector_state pointer, we would need
to get the connector itself and while usually we have a single connector
connected to the encoder, we can't really get it from the encoder at
the moment since it could be behind any number of bridges.

While this could be addressed by (for example) listing all the
connectors and finding the one that has the encoder as its source, it
feels like an unnecessary rework for something that is slowly getting
replaced by bridges.

Since all the users that matter have been converted, let's remove the
TODO item.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210219120032.260676-11-maxime@cerno.tech
This commit is contained in:
Maxime Ripard 2021-02-19 13:00:31 +01:00
parent 37418bf14c
commit c129b49825
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Documentation/gpu/todo.rst
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@ -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
------------------------------------------