drm/simple-kms: Add create_plane_state hook

The simple-kms helper provides a reset_plane hook to let drivers
override the default plane reset. However, the reset hook is
overloaded: it is used to create the initial software state at probe
time, but also to reset both the hardware and software state during
suspend/resume. These two roles have different expectations, and
reset is not fallible which makes error handling difficult.

The atomic_create_state pattern was introduced to untangle this by
providing a hook that only allocates and initializes a pristine state
without any side effect.

Add a create_plane_state hook to struct
drm_simple_display_pipe_funcs. When provided,
drm_simple_kms_plane_reset() will use it to allocate a fresh state,
falling back to reset_plane and then to the default
drm_atomic_helper_plane_reset().

This will allow simple-kms drivers to be converted to the
atomic_create_state pattern.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260814-drm-no-more-plane-reset-v2-1-82d2963dd134@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
index cb672ce0e856..b58f6d532820 100644
--- a/include/drm/drm_simple_kms_helper.h
+++ b/include/drm/drm_simple_kms_helper.h
@@ -44,6 +44,7 @@ struct drm_simple_display_pipe_funcs {
 	void (*destroy_crtc_state)(struct drm_simple_display_pipe *pipe,
 				   struct drm_crtc_state *crtc_state);
 	void (*reset_plane)(struct drm_simple_display_pipe *pipe);
+	struct drm_plane_state * (*create_plane_state)(struct drm_simple_display_pipe *pipe);
 	struct drm_plane_state * (*duplicate_plane_state)(struct drm_simple_display_pipe *pipe);
 	void (*destroy_plane_state)(struct drm_simple_display_pipe *pipe,
 				    struct drm_plane_state *plane_state);