diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index fdd82fcbf168..f694de756ecf 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -59,6 +59,31 @@ struct drm_bridge_funcs {
 	void (*detach)(struct drm_bridge *bridge);
 
 	/**
+	 * @mode_valid:
+	 *
+	 * This callback is used to check if a specific mode is valid in this
+	 * bridge. This should be implemented if the bridge has some sort of
+	 * restriction in the modes it can display. For example, a given bridge
+	 * 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.
+	 *
+	 * RETURNS:
+	 *
+	 * drm_mode_status Enum
+	 */
+	enum drm_mode_status (*mode_valid)(struct drm_bridge *crtc,
+					   const struct drm_display_mode *mode);
+
+	/**
 	 * @mode_fixup:
 	 *
 	 * This callback is used to validate and adjust a mode. The paramater
@@ -82,6 +107,12 @@ struct drm_bridge_funcs {
 	 * NOT touch any persistent state (hardware or software) or data
 	 * structures except the passed in @state parameter.
 	 *
+	 * 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 bridge constraints and
+	 * limits checks into @mode_valid.
+	 *
 	 * RETURNS:
 	 *
 	 * True if an acceptable configuration is possible, false if the modeset
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index c01c328f6cc8..91d071ff1232 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -106,6 +106,31 @@ struct drm_crtc_helper_funcs {
 	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.
+	 *
+	 * 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
@@ -132,20 +157,11 @@ struct drm_crtc_helper_funcs {
 	 * Atomic drivers which need to inspect and adjust more state should
 	 * instead use the @atomic_check callback.
 	 *
-	 * Also beware that neither core nor helpers filter modes before
-	 * passing them to the driver: While the list of modes that is
-	 * advertised to userspace is filtered using the
-	 * &drm_connector.mode_valid callback, neither the core nor the helpers
-	 * do any filtering on modes passed in from userspace when setting a
-	 * mode. It is therefore possible for userspace to pass in a mode that
-	 * was previously filtered out using &drm_connector.mode_valid or add a
-	 * custom mode that wasn't probed from EDID or similar to begin with.
-	 * Even though this is an advanced feature and rarely used nowadays,
-	 * some users rely on being able to specify modes manually so drivers
-	 * must be prepared to deal with it. Specifically this means that all
-	 * drivers need not only validate modes in &drm_connector.mode_valid but
-	 * also in this or in the &drm_encoder_helper_funcs.mode_fixup callback
-	 * to make sure invalid modes passed in from userspace are rejected.
+	 * 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:
 	 *
@@ -341,6 +357,12 @@ struct drm_crtc_helper_funcs {
 	 * 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
@@ -457,6 +479,31 @@ struct drm_encoder_helper_funcs {
 	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.
+	 *
+	 * 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
@@ -482,21 +529,11 @@ struct drm_encoder_helper_funcs {
 	 * Atomic drivers which need to inspect and adjust more state should
 	 * instead use the @atomic_check callback.
 	 *
-	 * Also beware that neither core nor helpers filter modes before
-	 * passing them to the driver: While the list of modes that is
-	 * advertised to userspace is filtered using the connector's
-	 * &drm_connector_helper_funcs.mode_valid callback, neither the core nor
-	 * the helpers do any filtering on modes passed in from userspace when
-	 * setting a mode. It is therefore possible for userspace to pass in a
-	 * mode that was previously filtered out using
-	 * &drm_connector_helper_funcs.mode_valid or add a custom mode that
-	 * wasn't probed from EDID or similar to begin with.  Even though this
-	 * is an advanced feature and rarely used nowadays, some users rely on
-	 * being able to specify modes manually so drivers must be prepared to
-	 * deal with it. Specifically this means that all drivers need not only
-	 * validate modes in &drm_connector.mode_valid but also in this or in
-	 * the &drm_crtc_helper_funcs.mode_fixup callback to make sure
-	 * invalid modes passed in from userspace are rejected.
+	 * 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:
 	 *
@@ -686,6 +723,12 @@ struct drm_encoder_helper_funcs {
 	 * 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
@@ -795,13 +838,20 @@ struct drm_connector_helper_funcs {
 	 * (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
-	 * GETCONNECOTR IOCTL. Userspace is free to create modes of its own and
-	 * ask the kernel to use them. It this case the atomic helpers or legacy
-	 * CRTC helpers will not call this function. Drivers therefore must
-	 * still fully validate any mode passed in in a modeset request.
+	 * 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
