From 58d426b5ed0d3ec6d7f3df32e32aab2c5b1daab5 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 26 May 2026 18:46:24 +0200 Subject: [PATCH] drm/crtc: 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 CRTCs. Reviewed-by: Dmitry Baryshkov Reviewed-by: Thomas Zimmermann Link: https://patch.msgid.link/20260526-drm-mode-config-init-v6-12-852346394200@kernel.org Signed-off-by: Maxime Ripard --- drivers/gpu/drm/drm_atomic_state_helper.c | 25 +++++++++++++++++ drivers/gpu/drm/drm_mode_config.c | 34 ++++++++++++++++++++++- include/drm/drm_atomic_state_helper.h | 2 ++ include/drm/drm_crtc.h | 16 +++++++++++ 4 files changed, 76 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c index b277f92f4532..8762171c9432 100644 --- a/drivers/gpu/drm/drm_atomic_state_helper.c +++ b/drivers/gpu/drm/drm_atomic_state_helper.c @@ -124,6 +124,31 @@ void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc) } EXPORT_SYMBOL(drm_atomic_helper_crtc_reset); +/** + * drm_atomic_helper_crtc_create_state - default &drm_crtc_funcs.atomic_create_state hook for crtcs + * @crtc: crtc object + * + * Allocates and initializes pristine @drm_crtc_state. + * + * This is useful for drivers that don't subclass @drm_crtc_state. + * + * RETURNS: + * Pointer to new crtc state, or ERR_PTR on failure. + */ +struct drm_crtc_state *drm_atomic_helper_crtc_create_state(struct drm_crtc *crtc) +{ + struct drm_crtc_state *state; + + state = kzalloc_obj(*state); + if (!state) + return ERR_PTR(-ENOMEM); + + __drm_atomic_helper_crtc_state_init(state, crtc); + + return state; +} +EXPORT_SYMBOL(drm_atomic_helper_crtc_create_state); + /** * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state * @crtc: CRTC object diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index fa609357858f..2e2cd18a14b4 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -208,6 +208,35 @@ static int drm_mode_config_plane_reset_with_create_state(struct drm_plane *plane return drm_mode_config_plane_create_state(plane); } +static int drm_mode_config_crtc_create_state(struct drm_crtc *crtc) +{ + struct drm_crtc_state *crtc_state; + + if (!crtc->funcs->atomic_create_state) + return 0; + + crtc_state = crtc->funcs->atomic_create_state(crtc); + if (IS_ERR(crtc_state)) + return PTR_ERR(crtc_state); + + if (drm_dev_has_vblank(crtc->dev)) + drm_crtc_vblank_reset(crtc); + + crtc->state = crtc_state; + + return 0; +} + +static int drm_mode_config_crtc_reset_with_create_state(struct drm_crtc *crtc) +{ + if (crtc->state) { + crtc->funcs->atomic_destroy_state(crtc, crtc->state); + crtc->state = NULL; + } + + return drm_mode_config_crtc_create_state(crtc); +} + /** * drm_mode_config_reset - call ->reset callbacks * @dev: drm device @@ -239,9 +268,12 @@ void drm_mode_config_reset(struct drm_device *dev) drm_mode_config_plane_reset_with_create_state(plane); } - drm_for_each_crtc(crtc, dev) + drm_for_each_crtc(crtc, dev) { if (crtc->funcs->reset) crtc->funcs->reset(crtc); + else if (crtc->funcs->atomic_create_state) + drm_mode_config_crtc_reset_with_create_state(crtc); + } drm_for_each_encoder(encoder, dev) if (encoder->funcs && encoder->funcs->reset) diff --git a/include/drm/drm_atomic_state_helper.h b/include/drm/drm_atomic_state_helper.h index 0bb72453464a..213f7e298008 100644 --- a/include/drm/drm_atomic_state_helper.h +++ b/include/drm/drm_atomic_state_helper.h @@ -45,6 +45,8 @@ void __drm_atomic_helper_crtc_state_init(struct drm_crtc_state *state, void __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc, struct drm_crtc_state *state); void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc); +struct drm_crtc_state * +drm_atomic_helper_crtc_create_state(struct drm_crtc *crtc); void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc, struct drm_crtc_state *state); struct drm_crtc_state * diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index c6dbe8b7db9e..152349f973e3 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -638,6 +638,22 @@ struct drm_crtc_funcs { int (*set_property)(struct drm_crtc *crtc, struct drm_property *property, uint64_t val); + /** + * @atomic_create_state: + * + * Allocate a pristine, initialized, state for the CRTC 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, CRTC state instance or an error pointer + * on failure. + */ + struct drm_crtc_state *(*atomic_create_state)(struct drm_crtc *crtc); + /** * @atomic_duplicate_state: *