drm_atomic_state_helper.c

/*
 * Copyright (C) 2018 Intel Corp.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 * Rob Clark <[email protected]>
 * Daniel Vetter <[email protected]>
 */

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_state_helper.h>
#include <drm/drm_blend.h>
#include <drm/drm_bridge.h>
#include <drm/drm_connector.h>
#include <drm/drm_crtc.h>
#include <drm/drm_device.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_plane.h>
#include <drm/drm_print.h>
#include <drm/drm_vblank.h>
#include <drm/drm_writeback.h>

#include <linux/export.h>
#include <linux/slab.h>
#include <linux/dma-fence.h>

/**
 * DOC: atomic state reset and initialization
 *
 * Both the drm core and the atomic helpers assume that there is always the full
 * and correct atomic software state for all connectors, CRTCs and planes
 * available. Which is a bit a problem on driver load and also after system
 * suspend. One way to solve this is to have a hardware state read-out
 * infrastructure which reconstructs the full software state (e.g. the i915
 * driver).
 *
 * The simpler solution is to just reset the software state to everything off,
 * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
 * the atomic helpers provide default reset implementations for all hooks.
 *
 * On the upside the precise state tracking of atomic simplifies system suspend
 * and resume a lot. For drivers using drm_mode_config_reset() a complete recipe
 * is implemented in drm_atomic_helper_suspend() and drm_atomic_helper_resume().
 * For other drivers the building blocks are split out, see the documentation
 * for these functions.
 */

/**
 * __drm_atomic_helper_crtc_state_reset - reset the CRTC state
 * @crtc_state: atomic CRTC state, must not be NULL
 * @crtc: CRTC object, must not be NULL
 *
 * Initializes the newly allocated @crtc_state with default
 * values. This is useful for drivers that subclass the CRTC state.
 */
void
__drm_atomic_helper_crtc_state_reset(struct drm_crtc_state *crtc_state,
				     struct drm_crtc *crtc)
{
	crtc_state->crtc = crtc;
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_state_reset);

/**
 * __drm_atomic_helper_crtc_reset - reset state on CRTC
 * @crtc: drm CRTC
 * @crtc_state: CRTC state to assign
 *
 * Initializes the newly allocated @crtc_state and assigns it to
 * the &drm_crtc->state pointer of @crtc, usually required when
 * initializing the drivers or when called from the &drm_crtc_funcs.reset
 * hook.
 *
 * This is useful for drivers that subclass the CRTC state.
 */
void
__drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
			       struct drm_crtc_state *crtc_state)
{
	if (crtc_state)
		__drm_atomic_helper_crtc_state_reset(crtc_state, crtc);

	if (drm_dev_has_vblank(crtc->dev))
		drm_crtc_vblank_reset(crtc);

	crtc->state = crtc_state;
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset);

/**
 * drm_atomic_helper_crtc_reset - default &drm_crtc_funcs.reset hook for CRTCs
 * @crtc: drm CRTC
 *
 * Resets the atomic state for @crtc by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
{
	struct drm_crtc_state *crtc_state =
		kzalloc(sizeof(*crtc->state), GFP_KERNEL);

	if (crtc->state)
		crtc->funcs->atomic_destroy_state(crtc, crtc->state);

	__drm_atomic_helper_crtc_reset(crtc, crtc_state);
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);

/**
 * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
 * @crtc: CRTC object
 * @state: atomic CRTC state
 *
 * Copies atomic state from a CRTC's current state and resets inferred values.
 * This is useful for drivers that subclass the CRTC state.
 */
void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
					      struct drm_crtc_state *state)
{
	memcpy(state, crtc->state, sizeof(*state));

	if (state->mode_blob)
		drm_property_blob_get(state->mode_blob);
	if (state->degamma_lut)
		drm_property_blob_get(state->degamma_lut);
	if (state->ctm)
		drm_property_blob_get(state->ctm);
	if (state->gamma_lut)
		drm_property_blob_get(state->gamma_lut);
	state->mode_changed = false;
	state->active_changed = false;
	state->planes_changed = false;
	state->connectors_changed = false;
	state->color_mgmt_changed = false;
	state->zpos_changed = false;
	state->commit = NULL;
	state->event = NULL;
	state->async_flip = false;

	/* Self refresh should be canceled when a new update is available */
	state->active = drm_atomic_crtc_effectively_active(state);
	state->self_refresh_active = false;
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);

/**
 * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
 * @crtc: drm CRTC
 *
 * Default CRTC state duplicate hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
struct drm_crtc_state *
drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
{
	struct drm_crtc_state *state;

	if (WARN_ON(!crtc->state))
		return NULL;

	state = kmalloc(sizeof(*state), GFP_KERNEL);
	if (state)
		__drm_atomic_helper_crtc_duplicate_state(crtc, state);

	return state;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);

/**
 * __drm_atomic_helper_crtc_destroy_state - release CRTC state
 * @state: CRTC state object to release
 *
 * Releases all resources stored in the CRTC state without actually freeing
 * the memory of the CRTC state. This is useful for drivers that subclass the
 * CRTC state.
 */
void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
{
	if (state->commit) {
		/*
		 * In the event that a non-blocking commit returns
		 * -ERESTARTSYS before the commit_tail work is queued, we will
		 * have an extra reference to the commit object. Release it, if
		 * the event has not been consumed by the worker.
		 *
		 * state->event may be freed, so we can't directly look at
		 * state->event->base.completion.
		 */
		if (state->event && state->commit->abort_completion)
			drm_crtc_commit_put(state->commit);

		kfree(state->commit->event);
		state->commit->event = NULL;

		drm_crtc_commit_put(state->commit);
	}

	drm_property_blob_put(state->mode_blob);
	drm_property_blob_put(state->degamma_lut);
	drm_property_blob_put(state->ctm);
	drm_property_blob_put(state->gamma_lut);
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);

/**
 * drm_atomic_helper_crtc_destroy_state - default state destroy hook
 * @crtc: drm CRTC
 * @state: CRTC state object to release
 *
 * Default CRTC state destroy hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
					  struct drm_crtc_state *state)
{
	__drm_atomic_helper_crtc_destroy_state(state);
	kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);

/**
 * __drm_atomic_helper_plane_state_reset - resets plane state to default values
 * @plane_state: atomic plane state, must not be NULL
 * @plane: plane object, must not be NULL
 *
 * Initializes the newly allocated @plane_state with default
 * values. This is useful for drivers that subclass the CRTC state.
 */
void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
					   struct drm_plane *plane)
{
	u64 val;

	plane_state->plane = plane;
	plane_state->rotation = DRM_MODE_ROTATE_0;

	plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
	plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;

	if (plane->color_encoding_property) {
		if (!drm_object_property_get_default_value(&plane->base,
							   plane->color_encoding_property,
							   &val))
			plane_state->color_encoding = val;
	}

	if (plane->color_range_property) {
		if (!drm_object_property_get_default_value(&plane->base,
							   plane->color_range_property,
							   &val))
			plane_state->color_range = val;
	}

	if (plane->color_pipeline_property) {
		/* default is always NULL, i.e., bypass */
		plane_state->color_pipeline = NULL;
	}

	if (plane->zpos_property) {
		if (!drm_object_property_get_default_value(&plane->base,
							   plane->zpos_property,
							   &val)) {
			plane_state->zpos = val;
			plane_state->normalized_zpos = val;
		}
	}

	if (plane->hotspot_x_property) {
		if (!drm_object_property_get_default_value(&plane->base,
							   plane->hotspot_x_property,
							   &val))
			plane_state->hotspot_x = val;
	}

	if (plane->hotspot_y_property) {
		if (!drm_object_property_get_default_value(&plane->base,
							   plane->hotspot_y_property,
							   &val))
			plane_state->hotspot_y = val;
	}
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_state_reset);

/**
 * __drm_atomic_helper_plane_reset - reset state on plane
 * @plane: drm plane
 * @plane_state: plane state to assign
 *
 * Initializes the newly allocated @plane_state and assigns it to
 * the &drm_crtc->state pointer of @plane, usually required when
 * initializing the drivers or when called from the &drm_plane_funcs.reset
 * hook.
 *
 * This is useful for drivers that subclass the plane state.
 */
void __drm_atomic_helper_plane_reset(struct drm_plane *plane,
				     struct drm_plane_state *plane_state)
{
	if (plane_state)
		__drm_atomic_helper_plane_state_reset(plane_state, plane);

	plane->state = plane_state;
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_reset);

/**
 * drm_atomic_helper_plane_reset - default &drm_plane_funcs.reset hook for planes
 * @plane: drm plane
 *
 * Resets the atomic state for @plane by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_plane_reset(struct drm_plane *plane)
{
	if (plane->state)
		__drm_atomic_helper_plane_destroy_state(plane->state);

	kfree(plane->state);
	plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
	if (plane->state)
		__drm_atomic_helper_plane_reset(plane, plane->state);
}
EXPORT_SYMBOL(drm_atomic_helper_plane_reset);

/**
 * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
 * @plane: plane object
 * @state: atomic plane state
 *
 * Copies atomic state from a plane's current state. This is useful for
 * drivers that subclass the plane state.
 */
void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
					       struct drm_plane_state *state)
{
	memcpy(state, plane->state, sizeof(*state));

	if (state->fb)
		drm_framebuffer_get(state->fb);

	state->fence = NULL;
	state->commit = NULL;
	state->fb_damage_clips = NULL;
	state->color_mgmt_changed = false;
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);

/**
 * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
 * @plane: drm plane
 *
 * Default plane state duplicate hook for drivers which don't have their own
 * subclassed plane state structure.
 */
struct drm_plane_state *
drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
{
	struct drm_plane_state *state;

	if (WARN_ON(!plane->state))
		return NULL;

	state = kmalloc(sizeof(*state), GFP_KERNEL);
	if (state)
		__drm_atomic_helper_plane_duplicate_state(plane, state);

	return state;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);

/**
 * __drm_atomic_helper_plane_destroy_state - release plane state
 * @state: plane state object to release
 *
 * Releases all resources stored in the plane state without actually freeing
 * the memory of the plane state. This is useful for drivers that subclass the
 * plane state.
 */
void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
{
	if (state->fb)
		drm_framebuffer_put(state->fb);

	if (state->fence)
		dma_fence_put(state->fence);

	if (state->commit)
		drm_crtc_commit_put(state->commit);

	drm_property_blob_put(state->fb_damage_clips);
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);

/**
 * drm_atomic_helper_plane_destroy_state - default state destroy hook
 * @plane: drm plane
 * @state: plane state object to release
 *
 * Default plane state destroy hook for drivers which don't have their own
 * subclassed plane state structure.
 */
void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
					   struct drm_plane_state *state)
{
	__drm_atomic_helper_plane_destroy_state(state);
	kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);

/**
 * __drm_atomic_helper_connector_state_reset - reset the connector state
 * @conn_state: atomic connector state, must not be NULL
 * @connector: connectotr object, must not be NULL
 *
 * Initializes the newly allocated @conn_state with default
 * values. This is useful for drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_state_reset(struct drm_connector_state *conn_state,
					  struct drm_connector *connector)
{
	conn_state->connector = connector;
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_state_reset);

/**
 * __drm_atomic_helper_connector_reset - reset state on connector
 * @connector: drm connector
 * @conn_state: connector state to assign
 *
 * Initializes the newly allocated @conn_state and assigns it to
 * the &drm_connector->state pointer of @connector, usually required when
 * initializing the drivers or when called from the &drm_connector_funcs.reset
 * hook.
 *
 * This is useful for drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_reset(struct drm_connector *connector,
				    struct drm_connector_state *conn_state)
{
	if (conn_state)
		__drm_atomic_helper_connector_state_reset(conn_state, connector);

	connector->state = conn_state;
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_reset);

/**
 * drm_atomic_helper_connector_reset - default &drm_connector_funcs.reset hook for connectors
 * @connector: drm connector
 *
 * Resets the atomic state for @connector by freeing the state pointer (which
 * might be NULL, e.g. at driver load time) and allocating a new empty state
 * object.
 */
void drm_atomic_helper_connector_reset(struct drm_connector *connector)
{
	struct drm_connector_state *conn_state =
		kzalloc(sizeof(*conn_state), GFP_KERNEL);

	if (connector->state)
		__drm_atomic_helper_connector_destroy_state(connector->state);

	kfree(connector->state);
	__drm_atomic_helper_connector_reset(connector, conn_state);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_reset);

/**
 * drm_atomic_helper_connector_tv_margins_reset - Resets TV connector properties
 * @connector: DRM connector
 *
 * Resets the TV-related properties attached to a connector.
 */
void drm_atomic_helper_connector_tv_margins_reset(struct drm_connector *connector)
{
	struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
	struct drm_connector_state *state = connector->state;

	state->tv.margins.left = cmdline->tv_margins.left;
	state->tv.margins.right = cmdline->tv_margins.right;
	state->tv.margins.top = cmdline->tv_margins.top;
	state->tv.margins.bottom = cmdline->tv_margins.bottom;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_tv_margins_reset);

/**
 * drm_atomic_helper_connector_tv_reset - Resets Analog TV connector properties
 * @connector: DRM connector
 *
 * Resets the analog TV properties attached to a connector
 */
void drm_atomic_helper_connector_tv_reset(struct drm_connector *connector)
{
	struct drm_device *dev = connector->dev;
	struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
	struct drm_connector_state *state = connector->state;
	struct drm_property *prop;
	uint64_t val;

	prop = dev->mode_config.tv_mode_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.mode = val;

	if (cmdline->tv_mode_specified)
		state->tv.mode = cmdline->tv_mode;

	prop = dev->mode_config.tv_select_subconnector_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.select_subconnector = val;

	prop = dev->mode_config.tv_subconnector_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.subconnector = val;

	prop = dev->mode_config.tv_brightness_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.brightness = val;

	prop = dev->mode_config.tv_contrast_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.contrast = val;

	prop = dev->mode_config.tv_flicker_reduction_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.flicker_reduction = val;

	prop = dev->mode_config.tv_overscan_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.overscan = val;

	prop = dev->mode_config.tv_saturation_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.saturation = val;

	prop = dev->mode_config.tv_hue_property;
	if (prop)
		if (!drm_object_property_get_default_value(&connector->base,
							   prop, &val))
			state->tv.hue = val;

	drm_atomic_helper_connector_tv_margins_reset(connector);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_tv_reset);

/**
 * drm_atomic_helper_connector_tv_check - Validate an analog TV connector state
 * @connector: DRM Connector
 * @state: the DRM State object
 *
 * Checks the state object to see if the requested state is valid for an
 * analog TV connector.
 *
 * Return:
 * %0 for success, a negative error code on error.
 */
int drm_atomic_helper_connector_tv_check(struct drm_connector *connector,
					 struct drm_atomic_state *state)
{
	struct drm_connector_state *old_conn_state =
		drm_atomic_get_old_connector_state(state, connector);
	struct drm_connector_state *new_conn_state =
		drm_atomic_get_new_connector_state(state, connector);
	struct drm_crtc_state *crtc_state;
	struct drm_crtc *crtc;

	crtc = new_conn_state->crtc;
	if (!crtc)
		return 0;

	crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
	if (!crtc_state)
		return -EINVAL;

	if (old_conn_state->tv.mode != new_conn_state->tv.mode)
		crtc_state->mode_changed = true;

	if (old_conn_state->tv.margins.left != new_conn_state->tv.margins.left ||
	    old_conn_state->tv.margins.right != new_conn_state->tv.margins.right ||
	    old_conn_state->tv.margins.top != new_conn_state->tv.margins.top ||
	    old_conn_state->tv.margins.bottom != new_conn_state->tv.margins.bottom ||
	    old_conn_state->tv.mode != new_conn_state->tv.mode ||
	    old_conn_state->tv.brightness != new_conn_state->tv.brightness ||
	    old_conn_state->tv.contrast != new_conn_state->tv.contrast ||
	    old_conn_state->tv.flicker_reduction != new_conn_state->tv.flicker_reduction ||
	    old_conn_state->tv.overscan != new_conn_state->tv.overscan ||
	    old_conn_state->tv.saturation != new_conn_state->tv.saturation ||
	    old_conn_state->tv.hue != new_conn_state->tv.hue)
		crtc_state->connectors_changed = true;

	return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_tv_check);

/**
 * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
 * @connector: connector object
 * @state: atomic connector state
 *
 * Copies atomic state from a connector's current state. This is useful for
 * drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
					    struct drm_connector_state *state)
{
	memcpy(state, connector->state, sizeof(*state));
	if (state->crtc)
		drm_connector_get(connector);
	state->commit = NULL;

	if (state->hdr_output_metadata)
		drm_property_blob_get(state->hdr_output_metadata);

	/* Don't copy over a writeback job, they are used only once */
	state->writeback_job = NULL;
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);

/**
 * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
 * @connector: drm connector
 *
 * Default connector state duplicate hook for drivers which don't have their own
 * subclassed connector state structure.
 */
struct drm_connector_state *
drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
{
	struct drm_connector_state *state;

	if (WARN_ON(!connector->state))
		return NULL;

	state = kmalloc(sizeof(*state), GFP_KERNEL);
	if (state)
		__drm_atomic_helper_connector_duplicate_state(connector, state);

	return state;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);

/**
 * __drm_atomic_helper_connector_destroy_state - release connector state
 * @state: connector state object to release
 *
 * Releases all resources stored in the connector state without actually
 * freeing the memory of the connector state. This is useful for drivers that
 * subclass the connector state.
 */
void
__drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
{
	if (state->crtc)
		drm_connector_put(state->connector);

	if (state->commit)
		drm_crtc_commit_put(state->commit);

	if (state->writeback_job)
		drm_writeback_cleanup_job(state->writeback_job);

	drm_property_blob_put(state->hdr_output_metadata);
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);

/**
 * drm_atomic_helper_connector_destroy_state - default state destroy hook
 * @connector: drm connector
 * @state: connector state object to release
 *
 * Default connector state destroy hook for drivers which don't have their own
 * subclassed connector state structure.
 */
void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
					  struct drm_connector_state *state)
{
	__drm_atomic_helper_connector_destroy_state(state);
	kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);

/**
 * __drm_atomic_helper_private_obj_duplicate_state - copy atomic private state
 * @obj: CRTC object
 * @state: new private object state
 *
 * Copies atomic state from a private objects's current state and resets inferred values.
 * This is useful for drivers that subclass the private state.
 */
void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj,
						     struct drm_private_state *state)
{
	memcpy(state, obj->state, sizeof(*state));
}
EXPORT_SYMBOL(__drm_atomic_helper_private_obj_duplicate_state);

/**
 * __drm_atomic_helper_bridge_duplicate_state() - Copy atomic bridge state
 * @bridge: bridge object
 * @state: atomic bridge state
 *
 * Copies atomic state from a bridge's current state and resets inferred values.
 * This is useful for drivers that subclass the bridge state.
 */
void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,
						struct drm_bridge_state *state)
{
	__drm_atomic_helper_private_obj_duplicate_state(&bridge->base,
							&state->base);
	state->bridge = bridge;
}
EXPORT_SYMBOL(__drm_atomic_helper_bridge_duplicate_state);

/**
 * drm_atomic_helper_bridge_duplicate_state() - Duplicate a bridge state object
 * @bridge: bridge object
 *
 * Allocates a new bridge state and initializes it with the current bridge
 * state values. This helper is meant to be used as a bridge
 * &drm_bridge_funcs.atomic_duplicate_state hook for bridges that don't
 * subclass the bridge state.
 */
struct drm_bridge_state *
drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge)
{
	struct drm_bridge_state *new;

	if (WARN_ON(!bridge->base.state))
		return NULL;

	new = kzalloc(sizeof(*new), GFP_KERNEL);
	if (new)
		__drm_atomic_helper_bridge_duplicate_state(bridge, new);

	return new;
}
EXPORT_SYMBOL(drm_atomic_helper_bridge_duplicate_state);

/**
 * drm_atomic_helper_bridge_destroy_state() - Destroy a bridge state object
 * @bridge: the bridge this state refers to
 * @state: bridge state to destroy
 *
 * Destroys a bridge state previously created by
 * &drm_atomic_helper_bridge_reset() or
 * &drm_atomic_helper_bridge_duplicate_state(). This helper is meant to be
 * used as a bridge &drm_bridge_funcs.atomic_destroy_state hook for bridges
 * that don't subclass the bridge state.
 */
void drm_atomic_helper_bridge_destroy_state(struct drm_bridge *bridge,
					    struct drm_bridge_state *state)
{
	kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_bridge_destroy_state);

/**
 * __drm_atomic_helper_bridge_reset() - Initialize a bridge state to its
 *					default
 * @bridge: the bridge this state refers to
 * @state: bridge state to initialize
 *
 * Initializes the bridge state to default values. This is meant to be called
 * by the bridge &drm_bridge_funcs.atomic_reset hook for bridges that subclass
 * the bridge state.
 */
void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,
				      struct drm_bridge_state *state)
{
	memset(state, 0, sizeof(*state));
	state->bridge = bridge;
}
EXPORT_SYMBOL(__drm_atomic_helper_bridge_reset);

/**
 * drm_atomic_helper_bridge_reset() - Allocate and initialize a bridge state
 *				      to its default
 * @bridge: the bridge this state refers to
 *
 * Allocates the bridge state and initializes it to default values. This helper
 * is meant to be used as a bridge &drm_bridge_funcs.atomic_reset hook for
 * bridges that don't subclass the bridge state.
 */
struct drm_bridge_state *
drm_atomic_helper_bridge_reset(struct drm_bridge *bridge)
{
	struct drm_bridge_state *bridge_state;

	bridge_state = kzalloc(sizeof(*bridge_state), GFP_KERNEL);
	if (!bridge_state)
		return ERR_PTR(-ENOMEM);

	__drm_atomic_helper_bridge_reset(bridge, bridge_state);
	return bridge_state;
}
EXPORT_SYMBOL(drm_atomic_helper_bridge_reset);