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drm/atomic: Convert __drm_atomic_get_current_plane_state() to modern accessor

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The __drm_atomic_get_current_plane_state() function tries to get and
return the existing plane state, and if it doesn't exist returns the one
stored in the drm_plane->state field.

Using the current nomenclature, it tries to get the existing plane state
with an ad-hoc implementation of drm_atomic_get_existing_plane_state(),
and falls back to either the old or new plane state, depending on
whether it is called before or after drm_atomic_helper_swap_state().

The existing plane state itself is deprecated, because it also changes
when swapping states from the new state to the old state.

Fortunately for us, we can simplify things. Indeed,
__drm_atomic_get_current_plane_state() is only used in two macros:
intel_atomic_crtc_state_for_each_plane_state and
drm_atomic_crtc_state_for_each_plane_state().

The intel variant is only used through the intel_wm_compute() function
that is only ever called in intel_crtc_atomic_check().

The generic variant is more widely used, and can be found in the malidp,
msm, tegra and vc4 drivers. All of these call sites though are during
atomic_check(), so we end up in the same situation than Intel's.

Thus, we only ever use the existing state as the new state, and
plane->state is always going to be the old state. Any plane isn't
guaranteed to be part of the state though, so we can't rely on
drm_atomic_get_old_plane_state() and we still need to use plane->state.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/20250930-drm-no-more-existing-state-v5-4-eeb9e1287907@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>
This commit is contained in:
Maxime Ripard
2025-09-30 12:59:19 +02:00
parent 9525f537ce
commit 6b592431c5
1 changed files with 13 additions and 7 deletions
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20
include/drm/drm_atomic.h
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@@ -793,11 +793,11 @@ drm_atomic_get_new_connector_state(const struct drm_atomic_state *state,
* @state: global atomic state object
* @plane: plane to grab
*
* This function returns the plane state for the given plane, either from
* @state, or if the plane isn't part of the atomic state update, from @plane.
* This is useful in atomic check callbacks, when drivers need to peek at, but
* not change, state of other planes, since it avoids threading an error code
* back up the call chain.
* This function returns the plane state for the given plane, either the
* new plane state from @state, or if the plane isn't part of the atomic
* state update, from @plane. This is useful in atomic check callbacks,
* when drivers need to peek at, but not change, state of other planes,
* since it avoids threading an error code back up the call chain.
*
* WARNING:
*
@@ -818,9 +818,15 @@ static inline const struct drm_plane_state *
__drm_atomic_get_current_plane_state(const struct drm_atomic_state *state,
struct drm_plane *plane)
{
if (state->planes[drm_plane_index(plane)].state)
return state->planes[drm_plane_index(plane)].state;
struct drm_plane_state *plane_state;
plane_state = drm_atomic_get_new_plane_state(state, plane);
if (plane_state)
return plane_state;
/*
* If the plane isn't part of the state, fallback to the currently active one.
*/
return plane->state;
}