drm: try to restore previous CRTC config if mode set fails

We restore the CRTC, encoder, and connector configurations, but if the
mode set failed, the attached display may have been turned off, so we
need to try set_config again to restore things to the way they were.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 982 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index f88a9b2c977b..edaf90319e1a 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -0,0 +1,982 @@
+/*
+ * Copyright (c) 2006-2008 Intel Corporation
+ * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
+ *
+ * DRM core CRTC related functions
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ *
+ * Authors:
+ *      Keith Packard
+ *	Eric Anholt <eric@anholt.net>
+ *      Dave Airlie <airlied@linux.ie>
+ *      Jesse Barnes <jesse.barnes@intel.com>
+ */
+
+#include "drmP.h"
+#include "drm_crtc.h"
+#include "drm_crtc_helper.h"
+#include "drm_fb_helper.h"
+
+static bool drm_kms_helper_poll = true;
+module_param_named(poll, drm_kms_helper_poll, bool, 0600);
+
+static void drm_mode_validate_flag(struct drm_connector *connector,
+				   int flags)
+{
+	struct drm_display_mode *mode, *t;
+
+	if (flags == (DRM_MODE_FLAG_DBLSCAN | DRM_MODE_FLAG_INTERLACE))
+		return;
+
+	list_for_each_entry_safe(mode, t, &connector->modes, head) {
+		if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
+				!(flags & DRM_MODE_FLAG_INTERLACE))
+			mode->status = MODE_NO_INTERLACE;
+		if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
+				!(flags & DRM_MODE_FLAG_DBLSCAN))
+			mode->status = MODE_NO_DBLESCAN;
+	}
+
+	return;
+}
+
+/**
+ * drm_helper_probe_single_connector_modes - get complete set of display modes
+ * @dev: DRM device
+ * @maxX: max width for modes
+ * @maxY: max height for modes
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Based on @dev's mode_config layout, scan all the connectors and try to detect
+ * modes on them.  Modes will first be added to the connector's probed_modes
+ * list, then culled (based on validity and the @maxX, @maxY parameters) and
+ * put into the normal modes list.
+ *
+ * Intended to be used either at bootup time or when major configuration
+ * changes have occurred.
+ *
+ * FIXME: take into account monitor limits
+ *
+ * RETURNS:
+ * Number of modes found on @connector.
+ */
+int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
+					    uint32_t maxX, uint32_t maxY)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_display_mode *mode, *t;
+	struct drm_connector_helper_funcs *connector_funcs =
+		connector->helper_private;
+	int count = 0;
+	int mode_flags = 0;
+
+	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
+			drm_get_connector_name(connector));
+	/* set all modes to the unverified state */
+	list_for_each_entry_safe(mode, t, &connector->modes, head)
+		mode->status = MODE_UNVERIFIED;
+
+	if (connector->force) {
+		if (connector->force == DRM_FORCE_ON)
+			connector->status = connector_status_connected;
+		else
+			connector->status = connector_status_disconnected;
+		if (connector->funcs->force)
+			connector->funcs->force(connector);
+	} else {
+		connector->status = connector->funcs->detect(connector, true);
+		drm_kms_helper_poll_enable(dev);
+	}
+
+	if (connector->status == connector_status_disconnected) {
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
+			connector->base.id, drm_get_connector_name(connector));
+		drm_mode_connector_update_edid_property(connector, NULL);
+		goto prune;
+	}
+
+	count = (*connector_funcs->get_modes)(connector);
+	if (count == 0 && connector->status == connector_status_connected)
+		count = drm_add_modes_noedid(connector, 1024, 768);
+	if (count == 0)
+		goto prune;
+
+	drm_mode_connector_list_update(connector);
+
+	if (maxX && maxY)
+		drm_mode_validate_size(dev, &connector->modes, maxX,
+				       maxY, 0);
+
+	if (connector->interlace_allowed)
+		mode_flags |= DRM_MODE_FLAG_INTERLACE;
+	if (connector->doublescan_allowed)
+		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
+	drm_mode_validate_flag(connector, mode_flags);
+
+	list_for_each_entry_safe(mode, t, &connector->modes, head) {
+		if (mode->status == MODE_OK)
+			mode->status = connector_funcs->mode_valid(connector,
+								   mode);
+	}
+
+prune:
+	drm_mode_prune_invalid(dev, &connector->modes, true);
+
+	if (list_empty(&connector->modes))
+		return 0;
+
+	drm_mode_sort(&connector->modes);
+
+	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
+			drm_get_connector_name(connector));
+	list_for_each_entry_safe(mode, t, &connector->modes, head) {
+		mode->vrefresh = drm_mode_vrefresh(mode);
+
+		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
+		drm_mode_debug_printmodeline(mode);
+	}
+
+	return count;
+}
+EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
+
+/**
+ * drm_helper_encoder_in_use - check if a given encoder is in use
+ * @encoder: encoder to check
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Walk @encoders's DRM device's mode_config and see if it's in use.
+ *
+ * RETURNS:
+ * True if @encoder is part of the mode_config, false otherwise.
+ */
+bool drm_helper_encoder_in_use(struct drm_encoder *encoder)
+{
+	struct drm_connector *connector;
+	struct drm_device *dev = encoder->dev;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder == encoder)
+			return true;
+	return false;
+}
+EXPORT_SYMBOL(drm_helper_encoder_in_use);
+
+/**
+ * drm_helper_crtc_in_use - check if a given CRTC is in a mode_config
+ * @crtc: CRTC to check
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Walk @crtc's DRM device's mode_config and see if it's in use.
+ *
+ * RETURNS:
+ * True if @crtc is part of the mode_config, false otherwise.
+ */
+bool drm_helper_crtc_in_use(struct drm_crtc *crtc)
+{
+	struct drm_encoder *encoder;
+	struct drm_device *dev = crtc->dev;
+	/* FIXME: Locking around list access? */
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head)
+		if (encoder->crtc == crtc && drm_helper_encoder_in_use(encoder))
+			return true;
+	return false;
+}
+EXPORT_SYMBOL(drm_helper_crtc_in_use);
+
+static void
+drm_encoder_disable(struct drm_encoder *encoder)
+{
+	struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
+
+	if (encoder_funcs->disable)
+		(*encoder_funcs->disable)(encoder);
+	else
+		(*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
+}
+
+/**
+ * drm_helper_disable_unused_functions - disable unused objects
+ * @dev: DRM device
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * If an connector or CRTC isn't part of @dev's mode_config, it can be disabled
+ * by calling its dpms function, which should power it off.
+ */
+void drm_helper_disable_unused_functions(struct drm_device *dev)
+{
+	struct drm_encoder *encoder;
+	struct drm_connector *connector;
+	struct drm_crtc *crtc;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (!connector->encoder)
+			continue;
+		if (connector->status == connector_status_disconnected)
+			connector->encoder = NULL;
+	}
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		if (!drm_helper_encoder_in_use(encoder)) {
+			drm_encoder_disable(encoder);
+			/* disconnector encoder from any connector */
+			encoder->crtc = NULL;
+		}
+	}
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+		crtc->enabled = drm_helper_crtc_in_use(crtc);
+		if (!crtc->enabled) {
+			if (crtc_funcs->disable)
+				(*crtc_funcs->disable)(crtc);
+			else
+				(*crtc_funcs->dpms)(crtc, DRM_MODE_DPMS_OFF);
+			crtc->fb = NULL;
+		}
+	}
+}
+EXPORT_SYMBOL(drm_helper_disable_unused_functions);
+
+/**
+ * drm_encoder_crtc_ok - can a given crtc drive a given encoder?
+ * @encoder: encoder to test
+ * @crtc: crtc to test
+ *
+ * Return false if @encoder can't be driven by @crtc, true otherwise.
+ */
+static bool drm_encoder_crtc_ok(struct drm_encoder *encoder,
+				struct drm_crtc *crtc)
+{
+	struct drm_device *dev;
+	struct drm_crtc *tmp;
+	int crtc_mask = 1;
+
+	WARN(!crtc, "checking null crtc?\n");
+
+	dev = crtc->dev;
+
+	list_for_each_entry(tmp, &dev->mode_config.crtc_list, head) {
+		if (tmp == crtc)
+			break;
+		crtc_mask <<= 1;
+	}
+
+	if (encoder->possible_crtcs & crtc_mask)
+		return true;
+	return false;
+}
+
+/*
+ * Check the CRTC we're going to map each output to vs. its current
+ * CRTC.  If they don't match, we have to disable the output and the CRTC
+ * since the driver will have to re-route things.
+ */
+static void
+drm_crtc_prepare_encoders(struct drm_device *dev)
+{
+	struct drm_encoder_helper_funcs *encoder_funcs;
+	struct drm_encoder *encoder;
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		encoder_funcs = encoder->helper_private;
+		/* Disable unused encoders */
+		if (encoder->crtc == NULL)
+			drm_encoder_disable(encoder);
+		/* Disable encoders whose CRTC is about to change */
+		if (encoder_funcs->get_crtc &&
+		    encoder->crtc != (*encoder_funcs->get_crtc)(encoder))
+			drm_encoder_disable(encoder);
+	}
+}
+
+/**
+ * drm_crtc_set_mode - set a mode
+ * @crtc: CRTC to program
+ * @mode: mode to use
+ * @x: width of mode
+ * @y: height of mode
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Try to set @mode on @crtc.  Give @crtc and its associated connectors a chance
+ * to fixup or reject the mode prior to trying to set it.
+ *
+ * RETURNS:
+ * True if the mode was set successfully, or false otherwise.
+ */
+bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
+			      struct drm_display_mode *mode,
+			      int x, int y,
+			      struct drm_framebuffer *old_fb)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_display_mode *adjusted_mode, saved_mode, saved_hwmode;
+	struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+	struct drm_encoder_helper_funcs *encoder_funcs;
+	int saved_x, saved_y;
+	struct drm_encoder *encoder;
+	bool ret = true;
+
+	crtc->enabled = drm_helper_crtc_in_use(crtc);
+	if (!crtc->enabled)
+		return true;
+
+	adjusted_mode = drm_mode_duplicate(dev, mode);
+
+	saved_hwmode = crtc->hwmode;
+	saved_mode = crtc->mode;
+	saved_x = crtc->x;
+	saved_y = crtc->y;
+
+	/* Update crtc values up front so the driver can rely on them for mode
+	 * setting.
+	 */
+	crtc->mode = *mode;
+	crtc->x = x;
+	crtc->y = y;
+
+	/* Pass our mode to the connectors and the CRTC to give them a chance to
+	 * adjust it according to limitations or connector properties, and also
+	 * a chance to reject the mode entirely.
+	 */
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+
+		if (encoder->crtc != crtc)
+			continue;
+		encoder_funcs = encoder->helper_private;
+		if (!(ret = encoder_funcs->mode_fixup(encoder, mode,
+						      adjusted_mode))) {
+			goto done;
+		}
+	}
+
+	if (!(ret = crtc_funcs->mode_fixup(crtc, mode, adjusted_mode))) {
+		goto done;
+	}
+	DRM_DEBUG_KMS("[CRTC:%d]\n", crtc->base.id);
+
+	/* Prepare the encoders and CRTCs before setting the mode. */
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+
+		if (encoder->crtc != crtc)
+			continue;
+		encoder_funcs = encoder->helper_private;
+		/* Disable the encoders as the first thing we do. */
+		encoder_funcs->prepare(encoder);
+	}
+
+	drm_crtc_prepare_encoders(dev);
+
+	crtc_funcs->prepare(crtc);
+
+	/* Set up the DPLL and any encoders state that needs to adjust or depend
+	 * on the DPLL.
+	 */
+	ret = !crtc_funcs->mode_set(crtc, mode, adjusted_mode, x, y, old_fb);
+	if (!ret)
+	    goto done;
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+
+		if (encoder->crtc != crtc)
+			continue;
+
+		DRM_DEBUG_KMS("[ENCODER:%d:%s] set [MODE:%d:%s]\n",
+			encoder->base.id, drm_get_encoder_name(encoder),
+			mode->base.id, mode->name);
+		encoder_funcs = encoder->helper_private;
+		encoder_funcs->mode_set(encoder, mode, adjusted_mode);
+	}
+
+	/* Now enable the clocks, plane, pipe, and connectors that we set up. */
+	crtc_funcs->commit(crtc);
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+
+		if (encoder->crtc != crtc)
+			continue;
+
+		encoder_funcs = encoder->helper_private;
+		encoder_funcs->commit(encoder);
+
+	}
+
+	/* Store real post-adjustment hardware mode. */
+	crtc->hwmode = *adjusted_mode;
+
+	/* Calculate and store various constants which
+	 * are later needed by vblank and swap-completion
+	 * timestamping. They are derived from true hwmode.
+	 */
+	drm_calc_timestamping_constants(crtc);
+
+	/* FIXME: add subpixel order */
+done:
+	drm_mode_destroy(dev, adjusted_mode);
+	if (!ret) {
+		crtc->hwmode = saved_hwmode;
+		crtc->mode = saved_mode;
+		crtc->x = saved_x;
+		crtc->y = saved_y;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_crtc_helper_set_mode);
+
+
+/**
+ * drm_crtc_helper_set_config - set a new config from userspace
+ * @crtc: CRTC to setup
+ * @crtc_info: user provided configuration
+ * @new_mode: new mode to set
+ * @connector_set: set of connectors for the new config
+ * @fb: new framebuffer
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Setup a new configuration, provided by the user in @crtc_info, and enable
+ * it.
+ *
+ * RETURNS:
+ * Zero. (FIXME)
+ */
+int drm_crtc_helper_set_config(struct drm_mode_set *set)
+{
+	struct drm_device *dev;
+	struct drm_crtc *save_crtcs, *new_crtc, *crtc;
+	struct drm_encoder *save_encoders, *new_encoder, *encoder;
+	struct drm_framebuffer *old_fb = NULL;
+	bool mode_changed = false; /* if true do a full mode set */
+	bool fb_changed = false; /* if true and !mode_changed just do a flip */
+	struct drm_connector *save_connectors, *connector;
+	int count = 0, ro, fail = 0;
+	struct drm_crtc_helper_funcs *crtc_funcs;
+	struct drm_mode_set save_set;
+	int ret = 0;
+	int i;
+
+	DRM_DEBUG_KMS("\n");
+
+	if (!set)
+		return -EINVAL;
+
+	if (!set->crtc)
+		return -EINVAL;
+
+	if (!set->crtc->helper_private)
+		return -EINVAL;
+
+	crtc_funcs = set->crtc->helper_private;
+
+	if (!set->mode)
+		set->fb = NULL;
+
+	if (set->fb) {
+		DRM_DEBUG_KMS("[CRTC:%d] [FB:%d] #connectors=%d (x y) (%i %i)\n",
+				set->crtc->base.id, set->fb->base.id,
+				(int)set->num_connectors, set->x, set->y);
+	} else {
+		DRM_DEBUG_KMS("[CRTC:%d] [NOFB]\n", set->crtc->base.id);
+		set->mode = NULL;
+		set->num_connectors = 0;
+	}
+
+	dev = set->crtc->dev;
+
+	/* Allocate space for the backup of all (non-pointer) crtc, encoder and
+	 * connector data. */
+	save_crtcs = kzalloc(dev->mode_config.num_crtc *
+			     sizeof(struct drm_crtc), GFP_KERNEL);
+	if (!save_crtcs)
+		return -ENOMEM;
+
+	save_encoders = kzalloc(dev->mode_config.num_encoder *
+				sizeof(struct drm_encoder), GFP_KERNEL);
+	if (!save_encoders) {
+		kfree(save_crtcs);
+		return -ENOMEM;
+	}
+
+	save_connectors = kzalloc(dev->mode_config.num_connector *
+				sizeof(struct drm_connector), GFP_KERNEL);
+	if (!save_connectors) {
+		kfree(save_crtcs);
+		kfree(save_encoders);
+		return -ENOMEM;
+	}
+
+	/* Copy data. Note that driver private data is not affected.
+	 * Should anything bad happen only the expected state is
+	 * restored, not the drivers personal bookkeeping.
+	 */
+	count = 0;
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		save_crtcs[count++] = *crtc;
+	}
+
+	count = 0;
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		save_encoders[count++] = *encoder;
+	}
+
+	count = 0;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		save_connectors[count++] = *connector;
+	}
+
+	save_set.crtc = set->crtc;
+	save_set.mode = &set->crtc->mode;
+	save_set.x = set->crtc->x;
+	save_set.y = set->crtc->y;
+	save_set.fb = set->crtc->fb;
+
+	/* We should be able to check here if the fb has the same properties
+	 * and then just flip_or_move it */
+	if (set->crtc->fb != set->fb) {
+		/* If we have no fb then treat it as a full mode set */
+		if (set->crtc->fb == NULL) {
+			DRM_DEBUG_KMS("crtc has no fb, full mode set\n");
+			mode_changed = true;
+		} else if (set->fb == NULL) {
+			mode_changed = true;
+		} else if (set->fb->depth != set->crtc->fb->depth) {
+			mode_changed = true;
+		} else if (set->fb->bits_per_pixel !=
+			   set->crtc->fb->bits_per_pixel) {
+			mode_changed = true;
+		} else
+			fb_changed = true;
+	}
+
+	if (set->x != set->crtc->x || set->y != set->crtc->y)
+		fb_changed = true;
+
+	if (set->mode && !drm_mode_equal(set->mode, &set->crtc->mode)) {
+		DRM_DEBUG_KMS("modes are different, full mode set\n");
+		drm_mode_debug_printmodeline(&set->crtc->mode);
+		drm_mode_debug_printmodeline(set->mode);
+		mode_changed = true;
+	}
+
+	/* a) traverse passed in connector list and get encoders for them */
+	count = 0;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		struct drm_connector_helper_funcs *connector_funcs =
+			connector->helper_private;
+		new_encoder = connector->encoder;
+		for (ro = 0; ro < set->num_connectors; ro++) {
+			if (set->connectors[ro] == connector) {
+				new_encoder = connector_funcs->best_encoder(connector);
+				/* if we can't get an encoder for a connector
+				   we are setting now - then fail */
+				if (new_encoder == NULL)
+					/* don't break so fail path works correct */
+					fail = 1;
+				break;
+			}
+		}
+
+		if (new_encoder != connector->encoder) {
+			DRM_DEBUG_KMS("encoder changed, full mode switch\n");
+			mode_changed = true;
+			/* If the encoder is reused for another connector, then
+			 * the appropriate crtc will be set later.
+			 */
+			if (connector->encoder)
+				connector->encoder->crtc = NULL;
+			connector->encoder = new_encoder;
+		}
+	}
+
+	if (fail) {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	count = 0;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (!connector->encoder)
+			continue;
+
+		if (connector->encoder->crtc == set->crtc)
+			new_crtc = NULL;
+		else
+			new_crtc = connector->encoder->crtc;
+
+		for (ro = 0; ro < set->num_connectors; ro++) {
+			if (set->connectors[ro] == connector)
+				new_crtc = set->crtc;
+		}
+
+		/* Make sure the new CRTC will work with the encoder */
+		if (new_crtc &&
+		    !drm_encoder_crtc_ok(connector->encoder, new_crtc)) {
+			ret = -EINVAL;
+			goto fail;
+		}
+		if (new_crtc != connector->encoder->crtc) {
+			DRM_DEBUG_KMS("crtc changed, full mode switch\n");
+			mode_changed = true;
+			connector->encoder->crtc = new_crtc;
+		}
+		if (new_crtc) {
+			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] to [CRTC:%d]\n",
+				connector->base.id, drm_get_connector_name(connector),
+				new_crtc->base.id);
+		} else {
+			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] to [NOCRTC]\n",
+				connector->base.id, drm_get_connector_name(connector));
+		}
+	}
+
+	/* mode_set_base is not a required function */
+	if (fb_changed && !crtc_funcs->mode_set_base)
+		mode_changed = true;
+
+	if (mode_changed) {
+		set->crtc->enabled = drm_helper_crtc_in_use(set->crtc);
+		if (set->crtc->enabled) {
+			DRM_DEBUG_KMS("attempting to set mode from"
+					" userspace\n");
+			drm_mode_debug_printmodeline(set->mode);
+			old_fb = set->crtc->fb;
+			set->crtc->fb = set->fb;
+			if (!drm_crtc_helper_set_mode(set->crtc, set->mode,
+						      set->x, set->y,
+						      old_fb)) {
+				DRM_ERROR("failed to set mode on [CRTC:%d]\n",
+					  set->crtc->base.id);
+				set->crtc->fb = old_fb;
+				ret = -EINVAL;
+				goto fail;
+			}
+			DRM_DEBUG_KMS("Setting connector DPMS state to on\n");
+			for (i = 0; i < set->num_connectors; i++) {
+				DRM_DEBUG_KMS("\t[CONNECTOR:%d:%s] set DPMS on\n", set->connectors[i]->base.id,
+					      drm_get_connector_name(set->connectors[i]));
+				set->connectors[i]->dpms = DRM_MODE_DPMS_ON;
+			}
+		}
+		drm_helper_disable_unused_functions(dev);
+	} else if (fb_changed) {
+		set->crtc->x = set->x;
+		set->crtc->y = set->y;
+
+		old_fb = set->crtc->fb;
+		if (set->crtc->fb != set->fb)
+			set->crtc->fb = set->fb;
+		ret = crtc_funcs->mode_set_base(set->crtc,
+						set->x, set->y, old_fb);
+		if (ret != 0) {
+			set->crtc->fb = old_fb;
+			goto fail;
+		}
+	}
+
+	kfree(save_connectors);
+	kfree(save_encoders);
+	kfree(save_crtcs);
+	return 0;
+
+fail:
+	/* Restore all previous data. */
+	count = 0;
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		*crtc = save_crtcs[count++];
+	}
+
+	count = 0;
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		*encoder = save_encoders[count++];
+	}
+
+	count = 0;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		*connector = save_connectors[count++];
+	}
+
+	/* Try to restore the config */
+	if (mode_changed &&
+	    !drm_crtc_helper_set_mode(save_set.crtc, save_set.mode, save_set.x,
+				      save_set.y, save_set.fb))
+		DRM_ERROR("failed to restore config after modeset failure\n");
+
+	kfree(save_connectors);
+	kfree(save_encoders);
+	kfree(save_crtcs);
+	return ret;
+}
+EXPORT_SYMBOL(drm_crtc_helper_set_config);
+
+static int drm_helper_choose_encoder_dpms(struct drm_encoder *encoder)
+{
+	int dpms = DRM_MODE_DPMS_OFF;
+	struct drm_connector *connector;
+	struct drm_device *dev = encoder->dev;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder == encoder)
+			if (connector->dpms < dpms)
+				dpms = connector->dpms;
+	return dpms;
+}
+
+static int drm_helper_choose_crtc_dpms(struct drm_crtc *crtc)
+{
+	int dpms = DRM_MODE_DPMS_OFF;
+	struct drm_connector *connector;
+	struct drm_device *dev = crtc->dev;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder && connector->encoder->crtc == crtc)
+			if (connector->dpms < dpms)
+				dpms = connector->dpms;
+	return dpms;
+}
+
+/**
+ * drm_helper_connector_dpms
+ * @connector affected connector
+ * @mode DPMS mode
+ *
+ * Calls the low-level connector DPMS function, then
+ * calls appropriate encoder and crtc DPMS functions as well
+ */
+void drm_helper_connector_dpms(struct drm_connector *connector, int mode)
+{
+	struct drm_encoder *encoder = connector->encoder;
+	struct drm_crtc *crtc = encoder ? encoder->crtc : NULL;
+	int old_dpms;
+
+	if (mode == connector->dpms)
+		return;
+
+	old_dpms = connector->dpms;
+	connector->dpms = mode;
+
+	/* from off to on, do crtc then encoder */
+	if (mode < old_dpms) {
+		if (crtc) {
+			struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+			if (crtc_funcs->dpms)
+				(*crtc_funcs->dpms) (crtc,
+						     drm_helper_choose_crtc_dpms(crtc));
+		}
+		if (encoder) {
+			struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
+			if (encoder_funcs->dpms)
+				(*encoder_funcs->dpms) (encoder,
+							drm_helper_choose_encoder_dpms(encoder));
+		}
+	}
+
+	/* from on to off, do encoder then crtc */
+	if (mode > old_dpms) {
+		if (encoder) {
+			struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
+			if (encoder_funcs->dpms)
+				(*encoder_funcs->dpms) (encoder,
+							drm_helper_choose_encoder_dpms(encoder));
+		}
+		if (crtc) {
+			struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+			if (crtc_funcs->dpms)
+				(*crtc_funcs->dpms) (crtc,
+						     drm_helper_choose_crtc_dpms(crtc));
+		}
+	}
+
+	return;
+}
+EXPORT_SYMBOL(drm_helper_connector_dpms);
+
+int drm_helper_mode_fill_fb_struct(struct drm_framebuffer *fb,
+				   struct drm_mode_fb_cmd *mode_cmd)
+{
+	fb->width = mode_cmd->width;
+	fb->height = mode_cmd->height;
+	fb->pitch = mode_cmd->pitch;
+	fb->bits_per_pixel = mode_cmd->bpp;
+	fb->depth = mode_cmd->depth;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_helper_mode_fill_fb_struct);
+
+int drm_helper_resume_force_mode(struct drm_device *dev)
+{
+	struct drm_crtc *crtc;
+	struct drm_encoder *encoder;
+	struct drm_encoder_helper_funcs *encoder_funcs;
+	struct drm_crtc_helper_funcs *crtc_funcs;
+	int ret;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+
+		if (!crtc->enabled)
+			continue;
+
+		ret = drm_crtc_helper_set_mode(crtc, &crtc->mode,
+					       crtc->x, crtc->y, crtc->fb);
+
+		if (ret == false)
+			DRM_ERROR("failed to set mode on crtc %p\n", crtc);
+
+		/* Turn off outputs that were already powered off */
+		if (drm_helper_choose_crtc_dpms(crtc)) {
+			list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+
+				if(encoder->crtc != crtc)
+					continue;
+
+				encoder_funcs = encoder->helper_private;
+				if (encoder_funcs->dpms)
+					(*encoder_funcs->dpms) (encoder,
+								drm_helper_choose_encoder_dpms(encoder));
+			}
+
+			crtc_funcs = crtc->helper_private;
+			if (crtc_funcs->dpms)
+				(*crtc_funcs->dpms) (crtc,
+						     drm_helper_choose_crtc_dpms(crtc));
+		}
+	}
+	/* disable the unused connectors while restoring the modesetting */
+	drm_helper_disable_unused_functions(dev);
+	return 0;
+}
+EXPORT_SYMBOL(drm_helper_resume_force_mode);
+
+#define DRM_OUTPUT_POLL_PERIOD (10*HZ)
+static void output_poll_execute(struct work_struct *work)
+{
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
+	struct drm_connector *connector;
+	enum drm_connector_status old_status;
+	bool repoll = false, changed = false;
+
+	if (!drm_kms_helper_poll)
+		return;
+
+	mutex_lock(&dev->mode_config.mutex);
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+
+		/* if this is HPD or polled don't check it -
+		   TV out for instance */
+		if (!connector->polled)
+			continue;
+
+		else if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT))
+			repoll = true;
+
+		old_status = connector->status;
+		/* if we are connected and don't want to poll for disconnect
+		   skip it */
+		if (old_status == connector_status_connected &&
+		    !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT) &&
+		    !(connector->polled & DRM_CONNECTOR_POLL_HPD))
+			continue;
+
+		connector->status = connector->funcs->detect(connector, false);
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %d to %d\n",
+			      connector->base.id,
+			      drm_get_connector_name(connector),
+			      old_status, connector->status);
+		if (old_status != connector->status)
+			changed = true;
+	}
+
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (changed) {
+		/* send a uevent + call fbdev */
+		drm_sysfs_hotplug_event(dev);
+		if (dev->mode_config.funcs->output_poll_changed)
+			dev->mode_config.funcs->output_poll_changed(dev);
+	}
+
+	if (repoll)
+		queue_delayed_work(system_nrt_wq, delayed_work, DRM_OUTPUT_POLL_PERIOD);
+}
+
+void drm_kms_helper_poll_disable(struct drm_device *dev)
+{
+	if (!dev->mode_config.poll_enabled)
+		return;
+	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
+}
+EXPORT_SYMBOL(drm_kms_helper_poll_disable);
+
+void drm_kms_helper_poll_enable(struct drm_device *dev)
+{
+	bool poll = false;
+	struct drm_connector *connector;
+
+	if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
+		return;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (connector->polled)
+			poll = true;
+	}
+
+	if (poll)
+		queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, DRM_OUTPUT_POLL_PERIOD);
+}
+EXPORT_SYMBOL(drm_kms_helper_poll_enable);
+
+void drm_kms_helper_poll_init(struct drm_device *dev)
+{
+	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
+	dev->mode_config.poll_enabled = true;
+
+	drm_kms_helper_poll_enable(dev);
+}
+EXPORT_SYMBOL(drm_kms_helper_poll_init);
+
+void drm_kms_helper_poll_fini(struct drm_device *dev)
+{
+	drm_kms_helper_poll_disable(dev);
+}
+EXPORT_SYMBOL(drm_kms_helper_poll_fini);
+
+void drm_helper_hpd_irq_event(struct drm_device *dev)
+{
+	if (!dev->mode_config.poll_enabled)
+		return;
+
+	/* kill timer and schedule immediate execution, this doesn't block */
+	cancel_delayed_work(&dev->mode_config.output_poll_work);
+	if (drm_kms_helper_poll)
+		queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, 0);
+}
+EXPORT_SYMBOL(drm_helper_hpd_irq_event);