From 1a185ddecaf9609e76ed289037afd6cb289e7bee Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 26 May 2026 18:46:22 +0200 Subject: [PATCH] drm/plane: Add new atomic_create_state callback Commit 47b5ac7daa46 ("drm/atomic: Add new atomic_create_state callback to drm_private_obj") introduced a new pattern for allocating drm object states. Instead of relying on the reset() callback, it created a new atomic_create_state hook. This is helpful because reset is a bit overloaded: it's used to create the initial software state, reset it, but also reset the hardware. It can also be used either at probe time, to create the initial state and possibly reset the hardware to an expected default, but also during suspend/resume. Both these cases come with different expectations too: during the initialization, we want to initialize all states, but during suspend/resume, drm_private_states for example are expected to be kept around. reset() also isn't fallible, which makes it harder to handle initialization errors properly. This is only really relevant for some drivers though, since all the helpers for reset only create a new state, and don't touch the hardware at all. It was thus decided to create a new hook that would allocate and initialize a pristine state without any side effect: atomic_create_state to untangle a bit some of it, and to separate the initialization with the actual reset one might need during a suspend/resume. Continue the transition to the new pattern with planes. Reviewed-by: Laurent Pinchart Reviewed-by: Thomas Zimmermann Link: https://patch.msgid.link/20260526-drm-mode-config-init-v6-10-852346394200@kernel.org Signed-off-by: Maxime Ripard --- drivers/gpu/drm/drm_atomic_state_helper.c | 25 ++++++++++++++++++ drivers/gpu/drm/drm_mode_config.c | 31 ++++++++++++++++++++++- include/drm/drm_atomic_state_helper.h | 2 ++ include/drm/drm_plane.h | 16 ++++++++++++ 4 files changed, 73 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c index ee01700d4ca7..ab171bfe6e86 100644 --- a/drivers/gpu/drm/drm_atomic_state_helper.c +++ b/drivers/gpu/drm/drm_atomic_state_helper.c @@ -340,6 +340,31 @@ void drm_atomic_helper_plane_reset(struct drm_plane *plane) } EXPORT_SYMBOL(drm_atomic_helper_plane_reset); +/** + * drm_atomic_helper_plane_create_state - default &drm_plane_funcs.atomic_create_state hook for planes + * @plane: plane object + * + * Allocates and initializes pristine @drm_plane_state. + * + * This is useful for drivers that don't subclass @drm_plane_state. + * + * RETURNS: + * Pointer to new plane state, or ERR_PTR on failure. + */ +struct drm_plane_state *drm_atomic_helper_plane_create_state(struct drm_plane *plane) +{ + struct drm_plane_state *state; + + state = kzalloc_obj(*state); + if (!state) + return ERR_PTR(-ENOMEM); + + __drm_atomic_helper_plane_state_init(state, plane); + + return state; +} +EXPORT_SYMBOL(drm_atomic_helper_plane_create_state); + /** * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state * @plane: plane object diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index c33382a38191..fa609357858f 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -182,6 +182,32 @@ int drm_mode_getresources(struct drm_device *dev, void *data, return ret; } +static int drm_mode_config_plane_create_state(struct drm_plane *plane) +{ + struct drm_plane_state *plane_state; + + if (!plane->funcs->atomic_create_state) + return 0; + + plane_state = plane->funcs->atomic_create_state(plane); + if (IS_ERR(plane_state)) + return PTR_ERR(plane_state); + + plane->state = plane_state; + + return 0; +} + +static int drm_mode_config_plane_reset_with_create_state(struct drm_plane *plane) +{ + if (plane->state) { + plane->funcs->atomic_destroy_state(plane, plane->state); + plane->state = NULL; + } + + return drm_mode_config_plane_create_state(plane); +} + /** * drm_mode_config_reset - call ->reset callbacks * @dev: drm device @@ -206,9 +232,12 @@ void drm_mode_config_reset(struct drm_device *dev) drm_for_each_colorop(colorop, dev) drm_colorop_reset(colorop); - drm_for_each_plane(plane, dev) + drm_for_each_plane(plane, dev) { if (plane->funcs->reset) plane->funcs->reset(plane); + else if (plane->funcs->atomic_create_state) + drm_mode_config_plane_reset_with_create_state(plane); + } drm_for_each_crtc(crtc, dev) if (crtc->funcs->reset) diff --git a/include/drm/drm_atomic_state_helper.h b/include/drm/drm_atomic_state_helper.h index 691c1ccfa4e0..8d1ef268fdef 100644 --- a/include/drm/drm_atomic_state_helper.h +++ b/include/drm/drm_atomic_state_helper.h @@ -55,6 +55,8 @@ void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc, void __drm_atomic_helper_plane_state_init(struct drm_plane_state *state, struct drm_plane *plane); +struct drm_plane_state * +drm_atomic_helper_plane_create_state(struct drm_plane *plane); void __drm_atomic_helper_plane_reset(struct drm_plane *plane, struct drm_plane_state *state); void drm_atomic_helper_plane_reset(struct drm_plane *plane); diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h index 419c88c873a6..2c5a5a70a71b 100644 --- a/include/drm/drm_plane.h +++ b/include/drm/drm_plane.h @@ -388,6 +388,22 @@ struct drm_plane_funcs { int (*set_property)(struct drm_plane *plane, struct drm_property *property, uint64_t val); + /** + * @atomic_create_state: + * + * Allocate a pristine, initialized, state for the plane object + * and return it. This callback must have no side effects: in + * particular, the returned state must not be assigned to the + * object's state pointer and it must not affect the hardware + * state. + * + * RETURNS: + * + * A new, pristine, plane state instance or an error pointer + * on failure. + */ + struct drm_plane_state *(*atomic_create_state)(struct drm_plane *plane); + /** * @atomic_duplicate_state: *