Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1252 insertions, 0 deletions

diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
new file mode 100644
index 000000000..0eb3372d0
--- /dev/null
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -0,0 +1,1252 @@
+/*
+ * Copyright © 2006 Keith Packard
+ * Copyright © 2007-2008 Dave Airlie
+ * Copyright © 2007-2008 Intel Corporation
+ *   Jesse Barnes <jesse.barnes@intel.com>
+ * Copyright © 2011-2013 Intel Corporation
+ * Copyright © 2015 Intel Corporation
+ *   Daniel Vetter <daniel.vetter@ffwll.ch>
+ *
+ * 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.
+ */
+
+#ifndef __DRM_MODESET_HELPER_VTABLES_H__
+#define __DRM_MODESET_HELPER_VTABLES_H__
+
+#include <drm/drm_crtc.h>
+#include <drm/drm_encoder.h>
+
+/**
+ * DOC: overview
+ *
+ * The DRM mode setting helper functions are common code for drivers to use if
+ * they wish.  Drivers are not forced to use this code in their
+ * implementations but it would be useful if the code they do use at least
+ * provides a consistent interface and operation to userspace. Therefore it is
+ * highly recommended to use the provided helpers as much as possible.
+ *
+ * Because there is only one pointer per modeset object to hold a vfunc table
+ * for helper libraries they are by necessity shared among the different
+ * helpers.
+ *
+ * To make this clear all the helper vtables are pulled together in this location here.
+ */
+
+enum mode_set_atomic;
+
+/**
+ * struct drm_crtc_helper_funcs - helper operations for CRTCs
+ *
+ * These hooks are used by the legacy CRTC helpers, the transitional plane
+ * helpers and the new atomic modesetting helpers.
+ */
+struct drm_crtc_helper_funcs {
+	/**
+	 * @dpms:
+	 *
+	 * Callback to control power levels on the CRTC.  If the mode passed in
+	 * is unsupported, the provider must use the next lowest power level.
+	 * This is used by the legacy CRTC helpers to implement DPMS
+	 * functionality in drm_helper_connector_dpms().
+	 *
+	 * This callback is also used to disable a CRTC by calling it with
+	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for enabling and disabling a CRTC to
+	 * facilitate transitions to atomic, but it is deprecated. Instead
+	 * @atomic_enable and @atomic_disable should be used.
+	 */
+	void (*dpms)(struct drm_crtc *crtc, int mode);
+
+	/**
+	 * @prepare:
+	 *
+	 * This callback should prepare the CRTC for a subsequent modeset, which
+	 * in practice means the driver should disable the CRTC if it is
+	 * running. Most drivers ended up implementing this by calling their
+	 * @dpms hook with DRM_MODE_DPMS_OFF.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for disabling a CRTC to facilitate
+	 * transitions to atomic, but it is deprecated. Instead @atomic_disable
+	 * should be used.
+	 */
+	void (*prepare)(struct drm_crtc *crtc);
+
+	/**
+	 * @commit:
+	 *
+	 * This callback should commit the new mode on the CRTC after a modeset,
+	 * which in practice means the driver should enable the CRTC.  Most
+	 * drivers ended up implementing this by calling their @dpms hook with
+	 * DRM_MODE_DPMS_ON.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for enabling a CRTC to facilitate
+	 * transitions to atomic, but it is deprecated. Instead @atomic_enable
+	 * should be used.
+	 */
+	void (*commit)(struct drm_crtc *crtc);
+
+	/**
+	 * @mode_valid:
+	 *
+	 * This callback is used to check if a specific mode is valid in this
+	 * crtc. This should be implemented if the crtc has some sort of
+	 * restriction in the modes it can display. For example, a given crtc
+	 * may be responsible to set a clock value. If the clock can not
+	 * produce all the values for the available modes then this callback
+	 * can be used to restrict the number of modes to only the ones that
+	 * can be displayed.
+	 *
+	 * This hook is used by the probe helpers to filter the mode list in
+	 * drm_helper_probe_single_connector_modes(), and it is used by the
+	 * atomic helpers to validate modes supplied by userspace in
+	 * drm_atomic_helper_check_modeset().
+	 *
+	 * This function is optional.
+	 *
+	 * NOTE:
+	 *
+	 * Since this function is both called from the check phase of an atomic
+	 * commit, and the mode validation in the probe paths it is not allowed
+	 * to look at anything else but the passed-in mode, and validate it
+	 * against configuration-invariant hardward constraints. Any further
+	 * limits which depend upon the configuration can only be checked in
+	 * @mode_fixup or @atomic_check.
+	 *
+	 * RETURNS:
+	 *
+	 * drm_mode_status Enum
+	 */
+	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
+					   const struct drm_display_mode *mode);
+
+	/**
+	 * @mode_fixup:
+	 *
+	 * This callback is used to validate a mode. The parameter mode is the
+	 * display mode that userspace requested, adjusted_mode is the mode the
+	 * encoders need to be fed with. Note that this is the inverse semantics
+	 * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup
+	 * vfunc. If the CRTC cannot support the requested conversion from mode
+	 * to adjusted_mode it should reject the modeset. See also
+	 * &drm_crtc_state.adjusted_mode for more details.
+	 *
+	 * This function is used by both legacy CRTC helpers and atomic helpers.
+	 * With atomic helpers it is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of atomic modesets, which
+	 * can be aborted for any reason (including on userspace's request to
+	 * just check whether a configuration would be possible). Atomic drivers
+	 * MUST NOT touch any persistent state (hardware or software) or data
+	 * structures except the passed in adjusted_mode parameter.
+	 *
+	 * This is in contrast to the legacy CRTC helpers where this was
+	 * allowed.
+	 *
+	 * Atomic drivers which need to inspect and adjust more state should
+	 * instead use the @atomic_check callback, but note that they're not
+	 * perfectly equivalent: @mode_valid is called from
+	 * drm_atomic_helper_check_modeset(), but @atomic_check is called from
+	 * drm_atomic_helper_check_planes(), because originally it was meant for
+	 * plane update checks only.
+	 *
+	 * Also beware that userspace can request its own custom modes, neither
+	 * core nor helpers filter modes to the list of probe modes reported by
+	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
+	 * that modes are filtered consistently put any CRTC constraints and
+	 * limits checks into @mode_valid.
+	 *
+	 * RETURNS:
+	 *
+	 * True if an acceptable configuration is possible, false if the modeset
+	 * operation should be rejected.
+	 */
+	bool (*mode_fixup)(struct drm_crtc *crtc,
+			   const struct drm_display_mode *mode,
+			   struct drm_display_mode *adjusted_mode);
+
+	/**
+	 * @mode_set:
+	 *
+	 * This callback is used by the legacy CRTC helpers to set a new mode,
+	 * position and framebuffer. Since it ties the primary plane to every
+	 * mode change it is incompatible with universal plane support. And
+	 * since it can't update other planes it's incompatible with atomic
+	 * modeset support.
+	 *
+	 * This callback is only used by CRTC helpers and deprecated.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or a negative error code on failure.
+	 */
+	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
+			struct drm_display_mode *adjusted_mode, int x, int y,
+			struct drm_framebuffer *old_fb);
+
+	/**
+	 * @mode_set_nofb:
+	 *
+	 * This callback is used to update the display mode of a CRTC without
+	 * changing anything of the primary plane configuration. This fits the
+	 * requirement of atomic and hence is used by the atomic helpers. It is
+	 * also used by the transitional plane helpers to implement a
+	 * @mode_set hook in drm_helper_crtc_mode_set().
+	 *
+	 * Note that the display pipe is completely off when this function is
+	 * called. Atomic drivers which need hardware to be running before they
+	 * program the new display mode (e.g. because they implement runtime PM)
+	 * should not use this hook. This is because the helper library calls
+	 * this hook only once per mode change and not every time the display
+	 * pipeline is suspended using either DPMS or the new "ACTIVE" property.
+	 * Which means register values set in this callback might get reset when
+	 * the CRTC is suspended, but not restored.  Such drivers should instead
+	 * move all their CRTC setup into the @atomic_enable callback.
+	 *
+	 * This callback is optional.
+	 */
+	void (*mode_set_nofb)(struct drm_crtc *crtc);
+
+	/**
+	 * @mode_set_base:
+	 *
+	 * This callback is used by the legacy CRTC helpers to set a new
+	 * framebuffer and scanout position. It is optional and used as an
+	 * optimized fast-path instead of a full mode set operation with all the
+	 * resulting flickering. If it is not present
+	 * drm_crtc_helper_set_config() will fall back to a full modeset, using
+	 * the @mode_set callback. Since it can't update other planes it's
+	 * incompatible with atomic modeset support.
+	 *
+	 * This callback is only used by the CRTC helpers and deprecated.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or a negative error code on failure.
+	 */
+	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
+			     struct drm_framebuffer *old_fb);
+
+	/**
+	 * @mode_set_base_atomic:
+	 *
+	 * This callback is used by the fbdev helpers to set a new framebuffer
+	 * and scanout without sleeping, i.e. from an atomic calling context. It
+	 * is only used to implement kgdb support.
+	 *
+	 * This callback is optional and only needed for kgdb support in the fbdev
+	 * helpers.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or a negative error code on failure.
+	 */
+	int (*mode_set_base_atomic)(struct drm_crtc *crtc,
+				    struct drm_framebuffer *fb, int x, int y,
+				    enum mode_set_atomic);
+
+	/**
+	 * @disable:
+	 *
+	 * This callback should be used to disable the CRTC. With the atomic
+	 * drivers it is called after all encoders connected to this CRTC have
+	 * been shut off already using their own
+	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
+	 * simple drivers can just add their own hooks and call it from this
+	 * CRTC callback here by looping over all encoders connected to it using
+	 * for_each_encoder_on_crtc().
+	 *
+	 * This hook is used both by legacy CRTC helpers and atomic helpers.
+	 * Atomic drivers don't need to implement it if there's no need to
+	 * disable anything at the CRTC level. To ensure that runtime PM
+	 * handling (using either DPMS or the new "ACTIVE" property) works
+	 * @disable must be the inverse of @atomic_enable for atomic drivers.
+	 * Atomic drivers should consider to use @atomic_disable instead of
+	 * this one.
+	 *
+	 * NOTE:
+	 *
+	 * With legacy CRTC helpers there's a big semantic difference between
+	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
+	 * CRTC: @disable is only called when also logically disabling the
+	 * display pipeline and needs to release any resources acquired in
+	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
+	 *
+	 * Therefore @disable must be the inverse of @mode_set plus @commit for
+	 * drivers still using legacy CRTC helpers, which is different from the
+	 * rules under atomic.
+	 */
+	void (*disable)(struct drm_crtc *crtc);
+
+	/**
+	 * @atomic_check:
+	 *
+	 * Drivers should check plane-update related CRTC constraints in this
+	 * hook. They can also check mode related limitations but need to be
+	 * aware of the calling order, since this hook is used by
+	 * drm_atomic_helper_check_planes() whereas the preparations needed to
+	 * check output routing and the display mode is done in
+	 * drm_atomic_helper_check_modeset(). Therefore drivers that want to
+	 * check output routing and display mode constraints in this callback
+	 * must ensure that drm_atomic_helper_check_modeset() has been called
+	 * beforehand. This is calling order used by the default helper
+	 * implementation in drm_atomic_helper_check().
+	 *
+	 * When using drm_atomic_helper_check_planes() this hook is called
+	 * after the &drm_plane_helper_funcs.atomic_check hook for planes, which
+	 * allows drivers to assign shared resources requested by planes in this
+	 * callback here. For more complicated dependencies the driver can call
+	 * the provided check helpers multiple times until the computed state
+	 * has a final configuration and everything has been checked.
+	 *
+	 * This function is also allowed to inspect any other object's state and
+	 * can add more state objects to the atomic commit if needed. Care must
+	 * be taken though to ensure that state check and compute functions for
+	 * these added states are all called, and derived state in other objects
+	 * all updated. Again the recommendation is to just call check helpers
+	 * until a maximal configuration is reached.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update. The
+	 * driver is not allowed to change anything outside of the free-standing
+	 * state objects passed-in or assembled in the overall &drm_atomic_state
+	 * update tracking structure.
+	 *
+	 * Also beware that userspace can request its own custom modes, neither
+	 * core nor helpers filter modes to the list of probe modes reported by
+	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
+	 * that modes are filtered consistently put any CRTC constraints and
+	 * limits checks into @mode_valid.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, -EINVAL if the state or the transition can't be
+	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+	 * attempt to obtain another state object ran into a &drm_modeset_lock
+	 * deadlock.
+	 */
+	int (*atomic_check)(struct drm_crtc *crtc,
+			    struct drm_crtc_state *state);
+
+	/**
+	 * @atomic_begin:
+	 *
+	 * Drivers should prepare for an atomic update of multiple planes on
+	 * a CRTC in this hook. Depending upon hardware this might be vblank
+	 * evasion, blocking updates by setting bits or doing preparatory work
+	 * for e.g. manual update display.
+	 *
+	 * This hook is called before any plane commit functions are called.
+	 *
+	 * Note that the power state of the display pipe when this function is
+	 * called depends upon the exact helpers and calling sequence the driver
+	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
+	 * the tradeoffs and variants of plane commit helpers.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 */
+	void (*atomic_begin)(struct drm_crtc *crtc,
+			     struct drm_crtc_state *old_crtc_state);
+	/**
+	 * @atomic_flush:
+	 *
+	 * Drivers should finalize an atomic update of multiple planes on
+	 * a CRTC in this hook. Depending upon hardware this might include
+	 * checking that vblank evasion was successful, unblocking updates by
+	 * setting bits or setting the GO bit to flush out all updates.
+	 *
+	 * Simple hardware or hardware with special requirements can commit and
+	 * flush out all updates for all planes from this hook and forgo all the
+	 * other commit hooks for plane updates.
+	 *
+	 * This hook is called after any plane commit functions are called.
+	 *
+	 * Note that the power state of the display pipe when this function is
+	 * called depends upon the exact helpers and calling sequence the driver
+	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
+	 * the tradeoffs and variants of plane commit helpers.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 */
+	void (*atomic_flush)(struct drm_crtc *crtc,
+			     struct drm_crtc_state *old_crtc_state);
+
+	/**
+	 * @atomic_enable:
+	 *
+	 * This callback should be used to enable the CRTC. With the atomic
+	 * drivers it is called before all encoders connected to this CRTC are
+	 * enabled through the encoder's own &drm_encoder_helper_funcs.enable
+	 * hook.  If that sequence is too simple drivers can just add their own
+	 * hooks and call it from this CRTC callback here by looping over all
+	 * encoders connected to it using for_each_encoder_on_crtc().
+	 *
+	 * This hook is used only by atomic helpers, for symmetry with
+	 * @atomic_disable. Atomic drivers don't need to implement it if there's
+	 * no need to enable anything at the CRTC level. To ensure that runtime
+	 * PM handling (using either DPMS or the new "ACTIVE" property) works
+	 * @atomic_enable must be the inverse of @atomic_disable for atomic
+	 * drivers.
+	 *
+	 * Drivers can use the @old_crtc_state input parameter if the operations
+	 * needed to enable the CRTC don't depend solely on the new state but
+	 * also on the transition between the old state and the new state.
+	 */
+	void (*atomic_enable)(struct drm_crtc *crtc,
+			      struct drm_crtc_state *old_crtc_state);
+
+	/**
+	 * @atomic_disable:
+	 *
+	 * This callback should be used to disable the CRTC. With the atomic
+	 * drivers it is called after all encoders connected to this CRTC have
+	 * been shut off already using their own
+	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
+	 * simple drivers can just add their own hooks and call it from this
+	 * CRTC callback here by looping over all encoders connected to it using
+	 * for_each_encoder_on_crtc().
+	 *
+	 * This hook is used only by atomic helpers. Atomic drivers don't
+	 * need to implement it if there's no need to disable anything at the
+	 * CRTC level.
+	 *
+	 * Comparing to @disable, this one provides the additional input
+	 * parameter @old_crtc_state which could be used to access the old
+	 * state. Atomic drivers should consider to use this one instead
+	 * of @disable.
+	 */
+	void (*atomic_disable)(struct drm_crtc *crtc,
+			       struct drm_crtc_state *old_crtc_state);
+};
+
+/**
+ * drm_crtc_helper_add - sets the helper vtable for a crtc
+ * @crtc: DRM CRTC
+ * @funcs: helper vtable to set for @crtc
+ */
+static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
+				       const struct drm_crtc_helper_funcs *funcs)
+{
+	crtc->helper_private = funcs;
+}
+
+/**
+ * struct drm_encoder_helper_funcs - helper operations for encoders
+ *
+ * These hooks are used by the legacy CRTC helpers, the transitional plane
+ * helpers and the new atomic modesetting helpers.
+ */
+struct drm_encoder_helper_funcs {
+	/**
+	 * @dpms:
+	 *
+	 * Callback to control power levels on the encoder.  If the mode passed in
+	 * is unsupported, the provider must use the next lowest power level.
+	 * This is used by the legacy encoder helpers to implement DPMS
+	 * functionality in drm_helper_connector_dpms().
+	 *
+	 * This callback is also used to disable an encoder by calling it with
+	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for enabling and disabling an encoder to
+	 * facilitate transitions to atomic, but it is deprecated. Instead
+	 * @enable and @disable should be used.
+	 */
+	void (*dpms)(struct drm_encoder *encoder, int mode);
+
+	/**
+	 * @mode_valid:
+	 *
+	 * This callback is used to check if a specific mode is valid in this
+	 * encoder. This should be implemented if the encoder has some sort
+	 * of restriction in the modes it can display. For example, a given
+	 * encoder may be responsible to set a clock value. If the clock can
+	 * not produce all the values for the available modes then this callback
+	 * can be used to restrict the number of modes to only the ones that
+	 * can be displayed.
+	 *
+	 * This hook is used by the probe helpers to filter the mode list in
+	 * drm_helper_probe_single_connector_modes(), and it is used by the
+	 * atomic helpers to validate modes supplied by userspace in
+	 * drm_atomic_helper_check_modeset().
+	 *
+	 * This function is optional.
+	 *
+	 * NOTE:
+	 *
+	 * Since this function is both called from the check phase of an atomic
+	 * commit, and the mode validation in the probe paths it is not allowed
+	 * to look at anything else but the passed-in mode, and validate it
+	 * against configuration-invariant hardward constraints. Any further
+	 * limits which depend upon the configuration can only be checked in
+	 * @mode_fixup or @atomic_check.
+	 *
+	 * RETURNS:
+	 *
+	 * drm_mode_status Enum
+	 */
+	enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
+					   const struct drm_display_mode *mode);
+
+	/**
+	 * @mode_fixup:
+	 *
+	 * This callback is used to validate and adjust a mode. The parameter
+	 * mode is the display mode that should be fed to the next element in
+	 * the display chain, either the final &drm_connector or a &drm_bridge.
+	 * The parameter adjusted_mode is the input mode the encoder requires. It
+	 * can be modified by this callback and does not need to match mode. See
+	 * also &drm_crtc_state.adjusted_mode for more details.
+	 *
+	 * This function is used by both legacy CRTC helpers and atomic helpers.
+	 * This hook is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of atomic modesets, which
+	 * can be aborted for any reason (including on userspace's request to
+	 * just check whether a configuration would be possible). Atomic drivers
+	 * MUST NOT touch any persistent state (hardware or software) or data
+	 * structures except the passed in adjusted_mode parameter.
+	 *
+	 * This is in contrast to the legacy CRTC helpers where this was
+	 * allowed.
+	 *
+	 * Atomic drivers which need to inspect and adjust more state should
+	 * instead use the @atomic_check callback. If @atomic_check is used,
+	 * this hook isn't called since @atomic_check allows a strict superset
+	 * of the functionality of @mode_fixup.
+	 *
+	 * Also beware that userspace can request its own custom modes, neither
+	 * core nor helpers filter modes to the list of probe modes reported by
+	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
+	 * that modes are filtered consistently put any encoder constraints and
+	 * limits checks into @mode_valid.
+	 *
+	 * RETURNS:
+	 *
+	 * True if an acceptable configuration is possible, false if the modeset
+	 * operation should be rejected.
+	 */
+	bool (*mode_fixup)(struct drm_encoder *encoder,
+			   const struct drm_display_mode *mode,
+			   struct drm_display_mode *adjusted_mode);
+
+	/**
+	 * @prepare:
+	 *
+	 * This callback should prepare the encoder for a subsequent modeset,
+	 * which in practice means the driver should disable the encoder if it
+	 * is running. Most drivers ended up implementing this by calling their
+	 * @dpms hook with DRM_MODE_DPMS_OFF.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for disabling an encoder to facilitate
+	 * transitions to atomic, but it is deprecated. Instead @disable should
+	 * be used.
+	 */
+	void (*prepare)(struct drm_encoder *encoder);
+
+	/**
+	 * @commit:
+	 *
+	 * This callback should commit the new mode on the encoder after a modeset,
+	 * which in practice means the driver should enable the encoder.  Most
+	 * drivers ended up implementing this by calling their @dpms hook with
+	 * DRM_MODE_DPMS_ON.
+	 *
+	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
+	 * also support using this hook for enabling an encoder to facilitate
+	 * transitions to atomic, but it is deprecated. Instead @enable should
+	 * be used.
+	 */
+	void (*commit)(struct drm_encoder *encoder);
+
+	/**
+	 * @mode_set:
+	 *
+	 * This callback is used to update the display mode of an encoder.
+	 *
+	 * Note that the display pipe is completely off when this function is
+	 * called. Drivers which need hardware to be running before they program
+	 * the new display mode (because they implement runtime PM) should not
+	 * use this hook, because the helper library calls it only once and not
+	 * every time the display pipeline is suspend using either DPMS or the
+	 * new "ACTIVE" property. Such drivers should instead move all their
+	 * encoder setup into the @enable callback.
+	 *
+	 * This callback is used both by the legacy CRTC helpers and the atomic
+	 * modeset helpers. It is optional in the atomic helpers.
+	 *
+	 * NOTE:
+	 *
+	 * If the driver uses the atomic modeset helpers and needs to inspect
+	 * the connector state or connector display info during mode setting,
+	 * @atomic_mode_set can be used instead.
+	 */
+	void (*mode_set)(struct drm_encoder *encoder,
+			 struct drm_display_mode *mode,
+			 struct drm_display_mode *adjusted_mode);
+
+	/**
+	 * @atomic_mode_set:
+	 *
+	 * This callback is used to update the display mode of an encoder.
+	 *
+	 * Note that the display pipe is completely off when this function is
+	 * called. Drivers which need hardware to be running before they program
+	 * the new display mode (because they implement runtime PM) should not
+	 * use this hook, because the helper library calls it only once and not
+	 * every time the display pipeline is suspended using either DPMS or the
+	 * new "ACTIVE" property. Such drivers should instead move all their
+	 * encoder setup into the @enable callback.
+	 *
+	 * This callback is used by the atomic modeset helpers in place of the
+	 * @mode_set callback, if set by the driver. It is optional and should
+	 * be used instead of @mode_set if the driver needs to inspect the
+	 * connector state or display info, since there is no direct way to
+	 * go from the encoder to the current connector.
+	 */
+	void (*atomic_mode_set)(struct drm_encoder *encoder,
+				struct drm_crtc_state *crtc_state,
+				struct drm_connector_state *conn_state);
+
+	/**
+	 * @get_crtc:
+	 *
+	 * This callback is used by the legacy CRTC helpers to work around
+	 * deficiencies in its own book-keeping.
+	 *
+	 * Do not use, use atomic helpers instead, which get the book keeping
+	 * right.
+	 *
+	 * FIXME:
+	 *
+	 * Currently only nouveau is using this, and as soon as nouveau is
+	 * atomic we can ditch this hook.
+	 */
+	struct drm_crtc *(*get_crtc)(struct drm_encoder *encoder);
+
+	/**
+	 * @detect:
+	 *
+	 * This callback can be used by drivers who want to do detection on the
+	 * encoder object instead of in connector functions.
+	 *
+	 * It is not used by any helper and therefore has purely driver-specific
+	 * semantics. New drivers shouldn't use this and instead just implement
+	 * their own private callbacks.
+	 *
+	 * FIXME:
+	 *
+	 * This should just be converted into a pile of driver vfuncs.
+	 * Currently radeon, amdgpu and nouveau are using it.
+	 */
+	enum drm_connector_status (*detect)(struct drm_encoder *encoder,
+					    struct drm_connector *connector);
+
+	/**
+	 * @disable:
+	 *
+	 * This callback should be used to disable the encoder. With the atomic
+	 * drivers it is called before this encoder's CRTC has been shut off
+	 * using their own &drm_crtc_helper_funcs.disable hook.  If that
+	 * sequence is too simple drivers can just add their own driver private
+	 * encoder hooks and call them from CRTC's callback by looping over all
+	 * encoders connected to it using for_each_encoder_on_crtc().
+	 *
+	 * This hook is used both by legacy CRTC helpers and atomic helpers.
+	 * Atomic drivers don't need to implement it if there's no need to
+	 * disable anything at the encoder level. To ensure that runtime PM
+	 * handling (using either DPMS or the new "ACTIVE" property) works
+	 * @disable must be the inverse of @enable for atomic drivers.
+	 *
+	 * NOTE:
+	 *
+	 * With legacy CRTC helpers there's a big semantic difference between
+	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
+	 * encoder: @disable is only called when also logically disabling the
+	 * display pipeline and needs to release any resources acquired in
+	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
+	 *
+	 * Therefore @disable must be the inverse of @mode_set plus @commit for
+	 * drivers still using legacy CRTC helpers, which is different from the
+	 * rules under atomic.
+	 */
+	void (*disable)(struct drm_encoder *encoder);
+
+	/**
+	 * @enable:
+	 *
+	 * This callback should be used to enable the encoder. With the atomic
+	 * drivers it is called after this encoder's CRTC has been enabled using
+	 * their own &drm_crtc_helper_funcs.enable hook.  If that sequence is
+	 * too simple drivers can just add their own driver private encoder
+	 * hooks and call them from CRTC's callback by looping over all encoders
+	 * connected to it using for_each_encoder_on_crtc().
+	 *
+	 * This hook is used only by atomic helpers, for symmetry with @disable.
+	 * Atomic drivers don't need to implement it if there's no need to
+	 * enable anything at the encoder level. To ensure that runtime PM handling
+	 * (using either DPMS or the new "ACTIVE" property) works
+	 * @enable must be the inverse of @disable for atomic drivers.
+	 */
+	void (*enable)(struct drm_encoder *encoder);
+
+	/**
+	 * @atomic_check:
+	 *
+	 * This callback is used to validate encoder state for atomic drivers.
+	 * Since the encoder is the object connecting the CRTC and connector it
+	 * gets passed both states, to be able to validate interactions and
+	 * update the CRTC to match what the encoder needs for the requested
+	 * connector.
+	 *
+	 * Since this provides a strict superset of the functionality of
+	 * @mode_fixup (the requested and adjusted modes are both available
+	 * through the passed in &struct drm_crtc_state) @mode_fixup is not
+	 * called when @atomic_check is implemented.
+	 *
+	 * This function is used by the atomic helpers, but it is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update. The
+	 * driver is not allowed to change anything outside of the free-standing
+	 * state objects passed-in or assembled in the overall &drm_atomic_state
+	 * update tracking structure.
+	 *
+	 * Also beware that userspace can request its own custom modes, neither
+	 * core nor helpers filter modes to the list of probe modes reported by
+	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
+	 * that modes are filtered consistently put any encoder constraints and
+	 * limits checks into @mode_valid.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, -EINVAL if the state or the transition can't be
+	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+	 * attempt to obtain another state object ran into a &drm_modeset_lock
+	 * deadlock.
+	 */
+	int (*atomic_check)(struct drm_encoder *encoder,
+			    struct drm_crtc_state *crtc_state,
+			    struct drm_connector_state *conn_state);
+};
+
+/**
+ * drm_encoder_helper_add - sets the helper vtable for an encoder
+ * @encoder: DRM encoder
+ * @funcs: helper vtable to set for @encoder
+ */
+static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
+					  const struct drm_encoder_helper_funcs *funcs)
+{
+	encoder->helper_private = funcs;
+}
+
+/**
+ * struct drm_connector_helper_funcs - helper operations for connectors
+ *
+ * These functions are used by the atomic and legacy modeset helpers and by the
+ * probe helpers.
+ */
+struct drm_connector_helper_funcs {
+	/**
+	 * @get_modes:
+	 *
+	 * This function should fill in all modes currently valid for the sink
+	 * into the &drm_connector.probed_modes list. It should also update the
+	 * EDID property by calling drm_connector_update_edid_property().
+	 *
+	 * The usual way to implement this is to cache the EDID retrieved in the
+	 * probe callback somewhere in the driver-private connector structure.
+	 * In this function drivers then parse the modes in the EDID and add
+	 * them by calling drm_add_edid_modes(). But connectors that driver a
+	 * fixed panel can also manually add specific modes using
+	 * drm_mode_probed_add(). Drivers which manually add modes should also
+	 * make sure that the &drm_connector.display_info,
+	 * &drm_connector.width_mm and &drm_connector.height_mm fields are
+	 * filled in.
+	 *
+	 * Virtual drivers that just want some standard VESA mode with a given
+	 * resolution can call drm_add_modes_noedid(), and mark the preferred
+	 * one using drm_set_preferred_mode().
+	 *
+	 * This function is only called after the @detect hook has indicated
+	 * that a sink is connected and when the EDID isn't overridden through
+	 * sysfs or the kernel commandline.
+	 *
+	 * This callback is used by the probe helpers in e.g.
+	 * drm_helper_probe_single_connector_modes().
+	 *
+	 * To avoid races with concurrent connector state updates, the helper
+	 * libraries always call this with the &drm_mode_config.connection_mutex
+	 * held. Because of this it's safe to inspect &drm_connector->state.
+	 *
+	 * RETURNS:
+	 *
+	 * The number of modes added by calling drm_mode_probed_add().
+	 */
+	int (*get_modes)(struct drm_connector *connector);
+
+	/**
+	 * @detect_ctx:
+	 *
+	 * Check to see if anything is attached to the connector. The parameter
+	 * force is set to false whilst polling, true when checking the
+	 * connector due to a user request. force can be used by the driver to
+	 * avoid expensive, destructive operations during automated probing.
+	 *
+	 * This callback is optional, if not implemented the connector will be
+	 * considered as always being attached.
+	 *
+	 * This is the atomic version of &drm_connector_funcs.detect.
+	 *
+	 * To avoid races against concurrent connector state updates, the
+	 * helper libraries always call this with ctx set to a valid context,
+	 * and &drm_mode_config.connection_mutex will always be locked with
+	 * the ctx parameter set to this ctx. This allows taking additional
+	 * locks as required.
+	 *
+	 * RETURNS:
+	 *
+	 * &drm_connector_status indicating the connector's status,
+	 * or the error code returned by drm_modeset_lock(), -EDEADLK.
+	 */
+	int (*detect_ctx)(struct drm_connector *connector,
+			  struct drm_modeset_acquire_ctx *ctx,
+			  bool force);
+
+	/**
+	 * @mode_valid:
+	 *
+	 * Callback to validate a mode for a connector, irrespective of the
+	 * specific display configuration.
+	 *
+	 * This callback is used by the probe helpers to filter the mode list
+	 * (which is usually derived from the EDID data block from the sink).
+	 * See e.g. drm_helper_probe_single_connector_modes().
+	 *
+	 * This function is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This only filters the mode list supplied to userspace in the
+	 * GETCONNECTOR IOCTL. Compared to &drm_encoder_helper_funcs.mode_valid,
+	 * &drm_crtc_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid,
+	 * which are also called by the atomic helpers from
+	 * drm_atomic_helper_check_modeset(). This allows userspace to force and
+	 * ignore sink constraint (like the pixel clock limits in the screen's
+	 * EDID), which is useful for e.g. testing, or working around a broken
+	 * EDID. Any source hardware constraint (which always need to be
+	 * enforced) therefore should be checked in one of the above callbacks,
+	 * and not this one here.
+	 *
+	 * To avoid races with concurrent connector state updates, the helper
+	 * libraries always call this with the &drm_mode_config.connection_mutex
+	 * held. Because of this it's safe to inspect &drm_connector->state.
+         *
+	 * RETURNS:
+	 *
+	 * Either &drm_mode_status.MODE_OK or one of the failure reasons in &enum
+	 * drm_mode_status.
+	 */
+	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
+					   struct drm_display_mode *mode);
+	/**
+	 * @best_encoder:
+	 *
+	 * This function should select the best encoder for the given connector.
+	 *
+	 * This function is used by both the atomic helpers (in the
+	 * drm_atomic_helper_check_modeset() function) and in the legacy CRTC
+	 * helpers.
+	 *
+	 * NOTE:
+	 *
+	 * In atomic drivers this function is called in the check phase of an
+	 * atomic update. The driver is not allowed to change or inspect
+	 * anything outside of arguments passed-in. Atomic drivers which need to
+	 * inspect dynamic configuration state should instead use
+	 * @atomic_best_encoder.
+	 *
+	 * You can leave this function to NULL if the connector is only
+	 * attached to a single encoder and you are using the atomic helpers.
+	 * In this case, the core will call drm_atomic_helper_best_encoder()
+	 * for you.
+	 *
+	 * RETURNS:
+	 *
+	 * Encoder that should be used for the given connector and connector
+	 * state, or NULL if no suitable encoder exists. Note that the helpers
+	 * will ensure that encoders aren't used twice, drivers should not check
+	 * for this.
+	 */
+	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
+
+	/**
+	 * @atomic_best_encoder:
+	 *
+	 * This is the atomic version of @best_encoder for atomic drivers which
+	 * need to select the best encoder depending upon the desired
+	 * configuration and can't select it statically.
+	 *
+	 * This function is used by drm_atomic_helper_check_modeset().
+	 * If it is not implemented, the core will fallback to @best_encoder
+	 * (or drm_atomic_helper_best_encoder() if @best_encoder is NULL).
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update. The
+	 * driver is not allowed to change anything outside of the free-standing
+	 * state objects passed-in or assembled in the overall &drm_atomic_state
+	 * update tracking structure.
+	 *
+	 * RETURNS:
+	 *
+	 * Encoder that should be used for the given connector and connector
+	 * state, or NULL if no suitable encoder exists. Note that the helpers
+	 * will ensure that encoders aren't used twice, drivers should not check
+	 * for this.
+	 */
+	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
+						   struct drm_connector_state *connector_state);
+
+	/**
+	 * @atomic_check:
+	 *
+	 * This hook is used to validate connector state. This function is
+	 * called from &drm_atomic_helper_check_modeset, and is called when
+	 * a connector property is set, or a modeset on the crtc is forced.
+	 *
+	 * Because &drm_atomic_helper_check_modeset may be called multiple times,
+	 * this function should handle being called multiple times as well.
+	 *
+	 * This function is also allowed to inspect any other object's state and
+	 * can add more state objects to the atomic commit if needed. Care must
+	 * be taken though to ensure that state check and compute functions for
+	 * these added states are all called, and derived state in other objects
+	 * all updated. Again the recommendation is to just call check helpers
+	 * until a maximal configuration is reached.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update. The
+	 * driver is not allowed to change anything outside of the free-standing
+	 * state objects passed-in or assembled in the overall &drm_atomic_state
+	 * update tracking structure.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, -EINVAL if the state or the transition can't be
+	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+	 * attempt to obtain another state object ran into a &drm_modeset_lock
+	 * deadlock.
+	 */
+	int (*atomic_check)(struct drm_connector *connector,
+			    struct drm_connector_state *state);
+
+	/**
+	 * @atomic_commit:
+	 *
+	 * This hook is to be used by drivers implementing writeback connectors
+	 * that need a point when to commit the writeback job to the hardware.
+	 * The writeback_job to commit is available in
+	 * &drm_connector_state.writeback_job.
+	 *
+	 * This hook is optional.
+	 *
+	 * This callback is used by the atomic modeset helpers.
+	 */
+	void (*atomic_commit)(struct drm_connector *connector,
+			      struct drm_connector_state *state);
+};
+
+/**
+ * drm_connector_helper_add - sets the helper vtable for a connector
+ * @connector: DRM connector
+ * @funcs: helper vtable to set for @connector
+ */
+static inline void drm_connector_helper_add(struct drm_connector *connector,
+					    const struct drm_connector_helper_funcs *funcs)
+{
+	connector->helper_private = funcs;
+}
+
+/**
+ * struct drm_plane_helper_funcs - helper operations for planes
+ *
+ * These functions are used by the atomic helpers and by the transitional plane
+ * helpers.
+ */
+struct drm_plane_helper_funcs {
+	/**
+	 * @prepare_fb:
+	 *
+	 * This hook is to prepare a framebuffer for scanout by e.g. pinning
+	 * it's backing storage or relocating it into a contiguous block of
+	 * VRAM. Other possible preparatory work includes flushing caches.
+	 *
+	 * This function must not block for outstanding rendering, since it is
+	 * called in the context of the atomic IOCTL even for async commits to
+	 * be able to return any errors to userspace. Instead the recommended
+	 * way is to fill out the &drm_plane_state.fence of the passed-in
+	 * &drm_plane_state. If the driver doesn't support native fences then
+	 * equivalent functionality should be implemented through private
+	 * members in the plane structure.
+	 *
+	 * Drivers which always have their buffers pinned should use
+	 * drm_gem_fb_prepare_fb() for this hook.
+	 *
+	 * The helpers will call @cleanup_fb with matching arguments for every
+	 * successful call to this hook.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or one of the following negative error codes allowed by
+	 * the &drm_mode_config_funcs.atomic_commit vfunc. When using helpers
+	 * this callback is the only one which can fail an atomic commit,
+	 * everything else must complete successfully.
+	 */
+	int (*prepare_fb)(struct drm_plane *plane,
+			  struct drm_plane_state *new_state);
+	/**
+	 * @cleanup_fb:
+	 *
+	 * This hook is called to clean up any resources allocated for the given
+	 * framebuffer and plane configuration in @prepare_fb.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 */
+	void (*cleanup_fb)(struct drm_plane *plane,
+			   struct drm_plane_state *old_state);
+
+	/**
+	 * @atomic_check:
+	 *
+	 * Drivers should check plane specific constraints in this hook.
+	 *
+	 * When using drm_atomic_helper_check_planes() plane's @atomic_check
+	 * hooks are called before the ones for CRTCs, which allows drivers to
+	 * request shared resources that the CRTC controls here. For more
+	 * complicated dependencies the driver can call the provided check helpers
+	 * multiple times until the computed state has a final configuration and
+	 * everything has been checked.
+	 *
+	 * This function is also allowed to inspect any other object's state and
+	 * can add more state objects to the atomic commit if needed. Care must
+	 * be taken though to ensure that state check and compute functions for
+	 * these added states are all called, and derived state in other objects
+	 * all updated. Again the recommendation is to just call check helpers
+	 * until a maximal configuration is reached.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update. The
+	 * driver is not allowed to change anything outside of the free-standing
+	 * state objects passed-in or assembled in the overall &drm_atomic_state
+	 * update tracking structure.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, -EINVAL if the state or the transition can't be
+	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+	 * attempt to obtain another state object ran into a &drm_modeset_lock
+	 * deadlock.
+	 */
+	int (*atomic_check)(struct drm_plane *plane,
+			    struct drm_plane_state *state);
+
+	/**
+	 * @atomic_update:
+	 *
+	 * Drivers should use this function to update the plane state.  This
+	 * hook is called in-between the &drm_crtc_helper_funcs.atomic_begin and
+	 * drm_crtc_helper_funcs.atomic_flush callbacks.
+	 *
+	 * Note that the power state of the display pipe when this function is
+	 * called depends upon the exact helpers and calling sequence the driver
+	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
+	 * the tradeoffs and variants of plane commit helpers.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 */
+	void (*atomic_update)(struct drm_plane *plane,
+			      struct drm_plane_state *old_state);
+	/**
+	 * @atomic_disable:
+	 *
+	 * Drivers should use this function to unconditionally disable a plane.
+	 * This hook is called in-between the
+	 * &drm_crtc_helper_funcs.atomic_begin and
+	 * drm_crtc_helper_funcs.atomic_flush callbacks. It is an alternative to
+	 * @atomic_update, which will be called for disabling planes, too, if
+	 * the @atomic_disable hook isn't implemented.
+	 *
+	 * This hook is also useful to disable planes in preparation of a modeset,
+	 * by calling drm_atomic_helper_disable_planes_on_crtc() from the
+	 * &drm_crtc_helper_funcs.disable hook.
+	 *
+	 * Note that the power state of the display pipe when this function is
+	 * called depends upon the exact helpers and calling sequence the driver
+	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
+	 * the tradeoffs and variants of plane commit helpers.
+	 *
+	 * This callback is used by the atomic modeset helpers and by the
+	 * transitional plane helpers, but it is optional.
+	 */
+	void (*atomic_disable)(struct drm_plane *plane,
+			       struct drm_plane_state *old_state);
+
+	/**
+	 * @atomic_async_check:
+	 *
+	 * Drivers should set this function pointer to check if the plane state
+	 * can be updated in a async fashion. Here async means "not vblank
+	 * synchronized".
+	 *
+	 * This hook is called by drm_atomic_async_check() to establish if a
+	 * given update can be committed asynchronously, that is, if it can
+	 * jump ahead of the state currently queued for update.
+	 *
+	 * RETURNS:
+	 *
+	 * Return 0 on success and any error returned indicates that the update
+	 * can not be applied in asynchronous manner.
+	 */
+	int (*atomic_async_check)(struct drm_plane *plane,
+				  struct drm_plane_state *state);
+
+	/**
+	 * @atomic_async_update:
+	 *
+	 * Drivers should set this function pointer to perform asynchronous
+	 * updates of planes, that is, jump ahead of the currently queued
+	 * state and update the plane. Here async means "not vblank
+	 * synchronized".
+	 *
+	 * This hook is called by drm_atomic_helper_async_commit().
+	 *
+	 * An async update will happen on legacy cursor updates. An async
+	 * update won't happen if there is an outstanding commit modifying
+	 * the same plane.
+	 *
+	 * Note that unlike &drm_plane_helper_funcs.atomic_update this hook
+	 * takes the new &drm_plane_state as parameter. When doing async_update
+	 * drivers shouldn't replace the &drm_plane_state but update the
+	 * current one with the new plane configurations in the new
+	 * plane_state.
+	 *
+	 * Drivers should also swap the framebuffers between current plane
+	 * state (&drm_plane.state) and new_state.
+	 * This is required since cleanup for async commits is performed on
+	 * the new state, rather than old state like for traditional commits.
+	 * Since we want to give up the reference on the current (old) fb
+	 * instead of our brand new one, swap them in the driver during the
+	 * async commit.
+	 *
+	 * FIXME:
+	 *  - It only works for single plane updates
+	 *  - Async Pageflips are not supported yet
+	 *  - Some hw might still scan out the old buffer until the next
+	 *    vblank, however we let go of the fb references as soon as
+	 *    we run this hook. For now drivers must implement their own workers
+	 *    for deferring if needed, until a common solution is created.
+	 */
+	void (*atomic_async_update)(struct drm_plane *plane,
+				    struct drm_plane_state *new_state);
+};
+
+/**
+ * drm_plane_helper_add - sets the helper vtable for a plane
+ * @plane: DRM plane
+ * @funcs: helper vtable to set for @plane
+ */
+static inline void drm_plane_helper_add(struct drm_plane *plane,
+					const struct drm_plane_helper_funcs *funcs)
+{
+	plane->helper_private = funcs;
+}
+
+/**
+ * struct drm_mode_config_helper_funcs - global modeset helper operations
+ *
+ * These helper functions are used by the atomic helpers.
+ */
+struct drm_mode_config_helper_funcs {
+	/**
+	 * @atomic_commit_tail:
+	 *
+	 * This hook is used by the default atomic_commit() hook implemented in
+	 * drm_atomic_helper_commit() together with the nonblocking commit
+	 * helpers (see drm_atomic_helper_setup_commit() for a starting point)
+	 * to implement blocking and nonblocking commits easily. It is not used
+	 * by the atomic helpers
+	 *
+	 * This function is called when the new atomic state has already been
+	 * swapped into the various state pointers. The passed in state
+	 * therefore contains copies of the old/previous state. This hook should
+	 * commit the new state into hardware. Note that the helpers have
+	 * already waited for preceeding atomic commits and fences, but drivers
+	 * can add more waiting calls at the start of their implementation, e.g.
+	 * to wait for driver-internal request for implicit syncing, before
+	 * starting to commit the update to the hardware.
+	 *
+	 * After the atomic update is committed to the hardware this hook needs
+	 * to call drm_atomic_helper_commit_hw_done(). Then wait for the upate
+	 * to be executed by the hardware, for example using
+	 * drm_atomic_helper_wait_for_vblanks() or
+	 * drm_atomic_helper_wait_for_flip_done(), and then clean up the old
+	 * framebuffers using drm_atomic_helper_cleanup_planes().
+	 *
+	 * When disabling a CRTC this hook _must_ stall for the commit to
+	 * complete. Vblank waits don't work on disabled CRTC, hence the core
+	 * can't take care of this. And it also can't rely on the vblank event,
+	 * since that can be signalled already when the screen shows black,
+	 * which can happen much earlier than the last hardware access needed to
+	 * shut off the display pipeline completely.
+	 *
+	 * This hook is optional, the default implementation is
+	 * drm_atomic_helper_commit_tail().
+	 */
+	void (*atomic_commit_tail)(struct drm_atomic_state *state);
+};
+
+#endif