Merge branch 'drm-fb-helper' of git://people.freedesktop.org/~danvet/drm into drm-next

This is the drm fb helper cleanup, mostly motivated by strange things I've
seen in my locking rework and the i915 modeset revamp. Compared to the
original submission I've reinstated the setup flexibility you'd like to
retain, kerneldoc has been reviewed by Laurent Pinchart and Rob Clark
reviewed the code changes.

Quick overview of the changes:
- Cleaned-up library interface for drivers using the fb helper, also
  simplified the fb allocation callback since no driver supported
  reallocating the fb on-the-fly. And the fbdev/fbcon code keeps pointers
  to the old mapping around anyway, so reallocating backing storage will
  be much more work.
- No longer call the crtc helper "disable everything" function at init
  time, but allow drivers to do so. Motivated by i915's fastboot effort
  and allows us to drop a bunch of noop dummy functions just to avoid
  calling NULL function pointers from i915.ko.
- Properly clear old state when doing modeset calls, the fb helper left
  some old modes in there and unconditionally set an fb (even when
  disabling a crtc). The crtc helpers didn't care, but i915 modeset code
  can now drop a few special cases.
- Full kerneldoc for the fb helper. Yay!
- My version of the "don't sleep in panic ->unblank calls". The patch is
  already in -mm, I guess Andrew can drop it as soon as this pull lands in
  drm-next.

* 'drm-fb-helper' of git://people.freedesktop.org/~danvet/drm:
  drm/fb-helper: remove unused members of struct drm_fb_helper
  drm/fb-helper: don't sleep for screen unblank when an oopps is in progress
  drm/fb-helper: improve kerneldoc
  drm/<drivers>: simplify ->fb_probe callback
  drm/fb-helper: streamline drm_fb_helper_single_fb_probe
  drm/fb-helper: directly call set_par from the hotplug handler
  drm/fb-helper: fixup set_config semantics
  drm/i915: rip out helper->disable noop functions
  drm/fb-helper: don't disable everything in initial_config
  drm/tegra: don't set up initial fbcon config twice
  drm/fb-helper: unexport drm_fb_helper_single_fb_probe
  drm/fb-helper: unexport drm_fb_helper_panic
  drm/fb-helper: kill drm_fb_helper_restore
  drm: review locking for drm_fb_helper_restore_fbdev_mode

Documentation/DocBook/drm.tmpl

@@ -2143,6 +2143,7 @@ void intel_crt_init(struct drm_device *dev)
       <title>fbdev Helper Functions Reference</title>
 !Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers
 !Edrivers/gpu/drm/drm_fb_helper.c
+!Iinclude/drm/drm_fb_helper.h
     </sect2>
     <sect2>
       <title>Display Port Helper Functions Reference</title>

drivers/gpu/drm/ast/ast_fb.c

@@ -40,6 +40,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_crtc_helper.h>
 #include "ast_drv.h"
 
 static void ast_dirty_update(struct ast_fbdev *afbdev,
@@ -145,9 +146,10 @@ static int astfb_create_object(struct ast_fbdev *afbdev,
 	return ret;
 }
 
-static int astfb_create(struct ast_fbdev *afbdev,
+static int astfb_create(struct drm_fb_helper *helper,
 			struct drm_fb_helper_surface_size *sizes)
 {
+	struct ast_fbdev *afbdev = (struct ast_fbdev *)helper;
 	struct drm_device *dev = afbdev->helper.dev;
 	struct drm_mode_fb_cmd2 mode_cmd;
 	struct drm_framebuffer *fb;
@@ -248,26 +250,10 @@ static void ast_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 	*blue = ast_crtc->lut_b[regno] << 8;
 }
 
-static int ast_find_or_create_single(struct drm_fb_helper *helper,
-					  struct drm_fb_helper_surface_size *sizes)
-{
-	struct ast_fbdev *afbdev = (struct ast_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = astfb_create(afbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static struct drm_fb_helper_funcs ast_fb_helper_funcs = {
 	.gamma_set = ast_fb_gamma_set,
 	.gamma_get = ast_fb_gamma_get,
-	.fb_probe = ast_find_or_create_single,
+	.fb_probe = astfb_create,
 };
 
 static void ast_fbdev_destroy(struct drm_device *dev,
@@ -314,6 +300,10 @@ int ast_fbdev_init(struct drm_device *dev)
 	}
 
 	drm_fb_helper_single_add_all_connectors(&afbdev->helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	drm_fb_helper_initial_config(&afbdev->helper, 32);
 	return 0;
 }

drivers/gpu/drm/cirrus/cirrus_fbdev.c

@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <drm/drmP.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_crtc_helper.h>
 
 #include <linux/fb.h>
 
@@ -120,9 +121,10 @@ static int cirrusfb_create_object(struct cirrus_fbdev *afbdev,
 	return ret;
 }
 
-static int cirrusfb_create(struct cirrus_fbdev *gfbdev,
+static int cirrusfb_create(struct drm_fb_helper *helper,
 			   struct drm_fb_helper_surface_size *sizes)
 {
+	struct cirrus_fbdev *gfbdev = (struct cirrus_fbdev *)helper;
 	struct drm_device *dev = gfbdev->helper.dev;
 	struct cirrus_device *cdev = gfbdev->helper.dev->dev_private;
 	struct fb_info *info;
@@ -219,23 +221,6 @@ out_iounmap:
 	return ret;
 }
 
-static int cirrus_fb_find_or_create_single(struct drm_fb_helper *helper,
-					   struct drm_fb_helper_surface_size
-					   *sizes)
-{
-	struct cirrus_fbdev *gfbdev = (struct cirrus_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = cirrusfb_create(gfbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static int cirrus_fbdev_destroy(struct drm_device *dev,
 				struct cirrus_fbdev *gfbdev)
 {
@@ -267,7 +252,7 @@ static int cirrus_fbdev_destroy(struct drm_device *dev,
 static struct drm_fb_helper_funcs cirrus_fb_helper_funcs = {
 	.gamma_set = cirrus_crtc_fb_gamma_set,
 	.gamma_get = cirrus_crtc_fb_gamma_get,
-	.fb_probe = cirrus_fb_find_or_create_single,
+	.fb_probe = cirrusfb_create,
 };
 
 int cirrus_fbdev_init(struct cirrus_device *cdev)
@@ -291,6 +276,9 @@ int cirrus_fbdev_init(struct cirrus_device *cdev)
 		return ret;
 	}
 	drm_fb_helper_single_add_all_connectors(&gfbdev->helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(cdev->dev);
 	drm_fb_helper_initial_config(&gfbdev->helper, bpp_sel);
 
 	return 0;

drivers/gpu/drm/drm_crtc.c

@@ -68,9 +68,23 @@ void drm_modeset_unlock_all(struct drm_device *dev)
 
 	mutex_unlock(&dev->mode_config.mutex);
 }
-
 EXPORT_SYMBOL(drm_modeset_unlock_all);
 
+/**
+ * drm_warn_on_modeset_not_all_locked - check that all modeset locks are locked
+ * @dev: device
+ */
+void drm_warn_on_modeset_not_all_locked(struct drm_device *dev)
+{
+	struct drm_crtc *crtc;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
+		WARN_ON(!mutex_is_locked(&crtc->mutex));
+
+	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
+}
+EXPORT_SYMBOL(drm_warn_on_modeset_not_all_locked);
+
 /* Avoid boilerplate.  I'm tired of typing. */
 #define DRM_ENUM_NAME_FN(fnname, list)				\
 	char *fnname(int val)					\

drivers/gpu/drm/drm_fb_cma_helper.c

@@ -275,23 +275,8 @@ err_drm_gem_cma_free_object:
 	return ret;
 }
 
-static int drm_fbdev_cma_probe(struct drm_fb_helper *helper,
-	struct drm_fb_helper_surface_size *sizes)
-{
-	int ret = 0;
-
-	if (!helper->fb) {
-		ret = drm_fbdev_cma_create(helper, sizes);
-		if (ret < 0)
-			return ret;
-		ret = 1;
-	}
-
-	return ret;
-}
-
 static struct drm_fb_helper_funcs drm_fb_cma_helper_funcs = {
-	.fb_probe = drm_fbdev_cma_probe,
+	.fb_probe = drm_fbdev_cma_create,
 };
 
 /**
@@ -333,6 +318,9 @@ struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev,
 
 	}
 
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	ret = drm_fb_helper_initial_config(helper, preferred_bpp);
 	if (ret < 0) {
 		dev_err(dev->dev, "Failed to set inital hw configuration.\n");
@@ -389,8 +377,10 @@ EXPORT_SYMBOL_GPL(drm_fbdev_cma_fini);
  */
 void drm_fbdev_cma_restore_mode(struct drm_fbdev_cma *fbdev_cma)
 {
+	drm_modeset_lock_all(dev);
 	if (fbdev_cma)
 		drm_fb_helper_restore_fbdev_mode(&fbdev_cma->fb_helper);
+	drm_modeset_unlock_all(dev);
 }
 EXPORT_SYMBOL_GPL(drm_fbdev_cma_restore_mode);
 

drivers/gpu/drm/drm_fb_helper.c

@@ -52,9 +52,36 @@ static LIST_HEAD(kernel_fb_helper_list);
  * mode setting driver. They can be used mostly independantely from the crtc
  * helper functions used by many drivers to implement the kernel mode setting
  * interfaces.
+ *
+ * Initialization is done as a three-step process with drm_fb_helper_init(),
+ * drm_fb_helper_single_add_all_connectors() and drm_fb_helper_initial_config().
+ * Drivers with fancier requirements than the default beheviour can override the
+ * second step with their own code.  Teardown is done with drm_fb_helper_fini().
+ *
+ * At runtime drivers should restore the fbdev console by calling
+ * drm_fb_helper_restore_fbdev_mode() from their ->lastclose callback. They
+ * should also notify the fb helper code from updates to the output
+ * configuration by calling drm_fb_helper_hotplug_event(). For easier
+ * integration with the output polling code in drm_crtc_helper.c the modeset
+ * code proves a ->output_poll_changed callback.
+ *
+ * All other functions exported by the fb helper library can be used to
+ * implement the fbdev driver interface by the driver.
  */
 
-/* simple single crtc case helper function */
+/**
+ * drm_fb_helper_single_add_all_connectors() - add all connectors to fbdev
+ * 					       emulation helper
+ * @fb_helper: fbdev initialized with drm_fb_helper_init
+ *
+ * This functions adds all the available connectors for use with the given
+ * fb_helper. This is a separate step to allow drivers to freely assign
+ * connectors to the fbdev, e.g. if some are reserved for special purposes or
+ * not adequate to be used for the fbcon.
+ *
+ * Since this is part of the initial setup before the fbdev is published, no
+ * locking is required.
+ */
 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
 {
 	struct drm_device *dev = fb_helper->dev;
@@ -163,6 +190,10 @@ static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
 	crtc->funcs->gamma_set(crtc, r_base, g_base, b_base, 0, crtc->gamma_size);
 }
 
+/**
+ * drm_fb_helper_debug_enter - implementation for ->fb_debug_enter
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_debug_enter(struct fb_info *info)
 {
 	struct drm_fb_helper *helper = info->par;
@@ -208,6 +239,10 @@ static struct drm_framebuffer *drm_mode_config_fb(struct drm_crtc *crtc)
 	return NULL;
 }
 
+/**
+ * drm_fb_helper_debug_leave - implementation for ->fb_debug_leave
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_debug_leave(struct fb_info *info)
 {
 	struct drm_fb_helper *helper = info->par;
@@ -239,10 +274,21 @@ int drm_fb_helper_debug_leave(struct fb_info *info)
 }
 EXPORT_SYMBOL(drm_fb_helper_debug_leave);
 
+/**
+ * drm_fb_helper_restore_fbdev_mode - restore fbdev configuration
+ * @fb_helper: fbcon to restore
+ *
+ * This should be called from driver's drm ->lastclose callback
+ * when implementing an fbcon on top of kms using this helper. This ensures that
+ * the user isn't greeted with a black screen when e.g. X dies.
+ */
 bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
 {
 	bool error = false;
 	int i, ret;
+
+	drm_warn_on_modeset_not_all_locked(fb_helper->dev);
+
 	for (i = 0; i < fb_helper->crtc_count; i++) {
 		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
 		ret = drm_mode_set_config_internal(mode_set);
@@ -253,6 +299,10 @@ bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
 }
 EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode);
 
+/*
+ * restore fbcon display for all kms driver's using this helper, used for sysrq
+ * and panic handling.
+ */
 static bool drm_fb_helper_force_kernel_mode(void)
 {
 	bool ret, error = false;
@@ -272,7 +322,7 @@ static bool drm_fb_helper_force_kernel_mode(void)
 	return error;
 }
 
-int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
+static int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
 			void *panic_str)
 {
 	/*
@@ -285,26 +335,11 @@ int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
 	pr_err("panic occurred, switching back to text console\n");
 	return drm_fb_helper_force_kernel_mode();
 }
-EXPORT_SYMBOL(drm_fb_helper_panic);
 
 static struct notifier_block paniced = {
 	.notifier_call = drm_fb_helper_panic,
 };
 
-/**
- * drm_fb_helper_restore - restore the framebuffer console (kernel) config
- *
- * Restore's the kernel's fbcon mode, used for lastclose & panic paths.
- */
-void drm_fb_helper_restore(void)
-{
-	bool ret;
-	ret = drm_fb_helper_force_kernel_mode();
-	if (ret == true)
-		DRM_ERROR("Failed to restore crtc configuration\n");
-}
-EXPORT_SYMBOL(drm_fb_helper_restore);
-
 static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper)
 {
 	struct drm_device *dev = fb_helper->dev;
@@ -326,7 +361,10 @@ static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper)
 #ifdef CONFIG_MAGIC_SYSRQ
 static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
 {
-	drm_fb_helper_restore();
+	bool ret;
+	ret = drm_fb_helper_force_kernel_mode();
+	if (ret == true)
+		DRM_ERROR("Failed to restore crtc configuration\n");
 }
 static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
 
@@ -352,6 +390,14 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
 	struct drm_connector *connector;
 	int i, j;
 
+	/*
+	 * fbdev->blank can be called from irq context in case of a panic.
+	 * Since we already have our own special panic handler which will
+	 * restore the fbdev console mode completely, just bail out early.
+	 */
+	if (oops_in_progress)
+		return;
+
 	/*
 	 * For each CRTC in this fb, turn the connectors on/off.
 	 */
@@ -378,6 +424,11 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
 	drm_modeset_unlock_all(dev);
 }
 
+/**
+ * drm_fb_helper_blank - implementation for ->fb_blank
+ * @blank: desired blanking state
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_blank(int blank, struct fb_info *info)
 {
 	switch (blank) {
@@ -421,6 +472,24 @@ static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
 	kfree(helper->crtc_info);
 }
 
+/**
+ * drm_fb_helper_init - initialize a drm_fb_helper structure
+ * @dev: drm device
+ * @fb_helper: driver-allocated fbdev helper structure to initialize
+ * @crtc_count: maximum number of crtcs to support in this fbdev emulation
+ * @max_conn_count: max connector count
+ *
+ * This allocates the structures for the fbdev helper with the given limits.
+ * Note that this won't yet touch the hardware (through the driver interfaces)
+ * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
+ * to allow driver writes more control over the exact init sequence.
+ *
+ * Drivers must set fb_helper->funcs before calling
+ * drm_fb_helper_initial_config().
+ *
+ * RETURNS:
+ * Zero if everything went ok, nonzero otherwise.
+ */
 int drm_fb_helper_init(struct drm_device *dev,
 		       struct drm_fb_helper *fb_helper,
 		       int crtc_count, int max_conn_count)
@@ -549,6 +618,11 @@ static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
 	return 0;
 }
 
+/**
+ * drm_fb_helper_setcmap - implementation for ->fb_setcmap
+ * @cmap: cmap to set
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
@@ -588,6 +662,11 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 }
 EXPORT_SYMBOL(drm_fb_helper_setcmap);
 
+/**
+ * drm_fb_helper_check_var - implementation for ->fb_check_var
+ * @var: screeninfo to check
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 			    struct fb_info *info)
 {
@@ -680,13 +759,19 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 }
 EXPORT_SYMBOL(drm_fb_helper_check_var);
 
-/* this will let fbcon do the mode init */
+/**
+ * drm_fb_helper_set_par - implementation for ->fb_set_par
+ * @info: fbdev registered by the helper
+ *
+ * This will let fbcon do the mode init and is called at initialization time by
+ * the fbdev core when registering the driver, and later on through the hotplug
+ * callback.
+ */
 int drm_fb_helper_set_par(struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 	struct drm_device *dev = fb_helper->dev;
 	struct fb_var_screeninfo *var = &info->var;
-	struct drm_crtc *crtc;
 	int ret;
 	int i;
 
@@ -697,7 +782,6 @@ int drm_fb_helper_set_par(struct fb_info *info)
 
 	drm_modeset_lock_all(dev);
 	for (i = 0; i < fb_helper->crtc_count; i++) {
-		crtc = fb_helper->crtc_info[i].mode_set.crtc;
 		ret = drm_mode_set_config_internal(&fb_helper->crtc_info[i].mode_set);
 		if (ret) {
 			drm_modeset_unlock_all(dev);
@@ -714,6 +798,11 @@ int drm_fb_helper_set_par(struct fb_info *info)
 }
 EXPORT_SYMBOL(drm_fb_helper_set_par);
 
+/**
+ * drm_fb_helper_pan_display - implementation for ->fb_pan_display
+ * @var: updated screen information
+ * @info: fbdev registered by the helper
+ */
 int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
 			      struct fb_info *info)
 {
@@ -751,10 +840,15 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
 }
 EXPORT_SYMBOL(drm_fb_helper_pan_display);
 
-int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
-				  int preferred_bpp)
+/*
+ * Allocates the backing storage and sets up the fbdev info structure through
+ * the ->fb_probe callback and then registers the fbdev and sets up the panic
+ * notifier.
+ */
+static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
+					 int preferred_bpp)
 {
-	int new_fb = 0;
+	int ret = 0;
 	int crtc_count = 0;
 	int i;
 	struct fb_info *info;
@@ -832,27 +926,30 @@ int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 	}
 
 	/* push down into drivers */
-	new_fb = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
-	if (new_fb < 0)
-		return new_fb;
+	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
+	if (ret < 0)
+		return ret;
 
 	info = fb_helper->fbdev;
 
-	/* set the fb pointer */
+	/*
+	 * Set the fb pointer - usually drm_setup_crtcs does this for hotplug
+	 * events, but at init time drm_setup_crtcs needs to be called before
+	 * the fb is allocated (since we need to figure out the desired size of
+	 * the fb before we can allocate it ...). Hence we need to fix things up
+	 * here again.
+	 */
 	for (i = 0; i < fb_helper->crtc_count; i++)
-		fb_helper->crtc_info[i].mode_set.fb = fb_helper->fb;
+		if (fb_helper->crtc_info[i].mode_set.num_connectors)
+			fb_helper->crtc_info[i].mode_set.fb = fb_helper->fb;
 
-	if (new_fb) {
-		info->var.pixclock = 0;
-		if (register_framebuffer(info) < 0)
-			return -EINVAL;
 
-		dev_info(fb_helper->dev->dev, "fb%d: %s frame buffer device\n",
-				info->node, info->fix.id);
+	info->var.pixclock = 0;
+	if (register_framebuffer(info) < 0)
+		return -EINVAL;
 
-	} else {
-		drm_fb_helper_set_par(info);
-	}
+	dev_info(fb_helper->dev->dev, "fb%d: %s frame buffer device\n",
+			info->node, info->fix.id);
 
 	/* Switch back to kernel console on panic */
 	/* multi card linked list maybe */
@@ -862,13 +959,25 @@ int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 					       &paniced);
 		register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
 	}
-	if (new_fb)
-		list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
+
+	list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
 
 	return 0;
 }
-EXPORT_SYMBOL(drm_fb_helper_single_fb_probe);
 
+/**
+ * drm_fb_helper_fill_fix - initializes fixed fbdev information
+ * @info: fbdev registered by the helper
+ * @pitch: desired pitch
+ * @depth: desired depth
+ *
+ * Helper to fill in the fixed fbdev information useful for a non-accelerated
+ * fbdev emulations. Drivers which support acceleration methods which impose
+ * additional constraints need to set up their own limits.
+ *
+ * Drivers should call this (or their equivalent setup code) from their
+ * ->fb_probe callback.
+ */
 void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
 			    uint32_t depth)
 {
@@ -889,6 +998,20 @@ void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
 }
 EXPORT_SYMBOL(drm_fb_helper_fill_fix);
 
+/**
+ * drm_fb_helper_fill_var - initalizes variable fbdev information
+ * @info: fbdev instance to set up
+ * @fb_helper: fb helper instance to use as template
+ * @fb_width: desired fb width
+ * @fb_height: desired fb height
+ *
+ * Sets up the variable fbdev metainformation from the given fb helper instance
+ * and the drm framebuffer allocated in fb_helper->fb.
+ *
+ * Drivers should call this (or their equivalent setup code) from their
+ * ->fb_probe callback after having allocated the fbdev backing
+ * storage framebuffer.
+ */
 void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
 			    uint32_t fb_width, uint32_t fb_height)
 {
@@ -1312,6 +1435,7 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
 	for (i = 0; i < fb_helper->crtc_count; i++) {
 		modeset = &fb_helper->crtc_info[i].mode_set;
 		modeset->num_connectors = 0;
+		modeset->fb = NULL;
 	}
 
 	for (i = 0; i < fb_helper->connector_count; i++) {
@@ -1328,9 +1452,21 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
 			modeset->mode = drm_mode_duplicate(dev,
 							   fb_crtc->desired_mode);
 			modeset->connectors[modeset->num_connectors++] = fb_helper->connector_info[i]->connector;
+			modeset->fb = fb_helper->fb;
 		}
 	}
 
+	/* Clear out any old modes if there are no more connected outputs. */
+	for (i = 0; i < fb_helper->crtc_count; i++) {
+		modeset = &fb_helper->crtc_info[i].mode_set;
+		if (modeset->num_connectors == 0) {
+			BUG_ON(modeset->fb);
+			BUG_ON(modeset->num_connectors);
+			if (modeset->mode)
+				drm_mode_destroy(dev, modeset->mode);
+			modeset->mode = NULL;
+		}
+	}
 out:
 	kfree(crtcs);
 	kfree(modes);
@@ -1338,18 +1474,23 @@ out:
 }
 
 /**
- * drm_helper_initial_config - setup a sane initial connector configuration
+ * drm_fb_helper_initial_config - setup a sane initial connector configuration
  * @fb_helper: fb_helper device struct
  * @bpp_sel: bpp value to use for the framebuffer configuration
  *
- * LOCKING:
- * Called at init time by the driver to set up the @fb_helper initial
- * configuration, must take the mode config lock.
- *
  * Scans the CRTCs and connectors and tries to put together an initial setup.
  * At the moment, this is a cloned configuration across all heads with
  * a new framebuffer object as the backing store.
  *
+ * Note that this also registers the fbdev and so allows userspace to call into
+ * the driver through the fbdev interfaces.
+ *
+ * This function will call down into the ->fb_probe callback to let
+ * the driver allocate and initialize the fbdev info structure and the drm
+ * framebuffer used to back the fbdev. drm_fb_helper_fill_var() and
+ * drm_fb_helper_fill_fix() are provided as helpers to setup simple default
+ * values for the fbdev info structure.
+ *
  * RETURNS:
  * Zero if everything went ok, nonzero otherwise.
  */
@@ -1358,9 +1499,6 @@ bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
 	struct drm_device *dev = fb_helper->dev;
 	int count = 0;
 
-	/* disable all the possible outputs/crtcs before entering KMS mode */
-	drm_helper_disable_unused_functions(fb_helper->dev);
-
 	drm_fb_helper_parse_command_line(fb_helper);
 
 	count = drm_fb_helper_probe_connector_modes(fb_helper,
@@ -1383,12 +1521,17 @@ EXPORT_SYMBOL(drm_fb_helper_initial_config);
  *                               probing all the outputs attached to the fb
  * @fb_helper: the drm_fb_helper
  *
- * LOCKING:
- * Called at runtime, must take mode config lock.
- *
  * Scan the connectors attached to the fb_helper and try to put together a
  * setup after *notification of a change in output configuration.
  *
+ * Called at runtime, takes the mode config locks to be able to check/change the
+ * modeset configuration. Must be run from process context (which usually means
+ * either the output polling work or a work item launched from the driver's
+ * hotplug interrupt).
+ *
+ * Note that the driver must ensure that this is only called _after_ the fb has
+ * been fully set up, i.e. after the call to drm_fb_helper_initial_config.
+ *
  * RETURNS:
  * 0 on success and a non-zero error code otherwise.
  */
@@ -1418,7 +1561,9 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
 	drm_setup_crtcs(fb_helper);
 	drm_modeset_unlock_all(dev);
 
-	return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
+	drm_fb_helper_set_par(fb_helper->fbdev);
+
+	return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
 

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -226,36 +226,8 @@ out:
 	return ret;
 }
 
-static int exynos_drm_fbdev_probe(struct drm_fb_helper *helper,
-				   struct drm_fb_helper_surface_size *sizes)
-{
-	int ret = 0;
-
-	DRM_DEBUG_KMS("%s\n", __FILE__);
-
-	/*
-	 * with !helper->fb, it means that this funcion is called first time
-	 * and after that, the helper->fb would be used as clone mode.
-	 */
-	if (!helper->fb) {
-		ret = exynos_drm_fbdev_create(helper, sizes);
-		if (ret < 0) {
-			DRM_ERROR("failed to create fbdev.\n");
-			return ret;
-		}
-
-		/*
-		 * fb_helper expects a value more than 1 if succeed
-		 * because register_framebuffer() should be called.
-		 */
-		ret = 1;
-	}
-
-	return ret;
-}
-
 static struct drm_fb_helper_funcs exynos_drm_fb_helper_funcs = {
-	.fb_probe =	exynos_drm_fbdev_probe,
+	.fb_probe =	exynos_drm_fbdev_create,
 };
 
 int exynos_drm_fbdev_init(struct drm_device *dev)
@@ -295,6 +267,9 @@ int exynos_drm_fbdev_init(struct drm_device *dev)
 
 	}
 
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	ret = drm_fb_helper_initial_config(helper, PREFERRED_BPP);
 	if (ret < 0) {
 		DRM_ERROR("failed to set up hw configuration.\n");
@@ -376,5 +351,7 @@ void exynos_drm_fbdev_restore_mode(struct drm_device *dev)
 	if (!private || !private->fb_helper)
 		return;
 
+	drm_modeset_lock_all(dev);
 	drm_fb_helper_restore_fbdev_mode(private->fb_helper);
+	drm_modeset_unlock_all(dev);
 }

drivers/gpu/drm/gma500/framebuffer.c

@@ -545,9 +545,7 @@ static int psbfb_probe(struct drm_fb_helper *helper,
 	struct psb_fbdev *psb_fbdev = (struct psb_fbdev *)helper;
 	struct drm_device *dev = psb_fbdev->psb_fb_helper.dev;
 	struct drm_psb_private *dev_priv = dev->dev_private;
-	int new_fb = 0;
 	int bytespp;
-	int ret;
 
 	bytespp = sizes->surface_bpp / 8;
 	if (bytespp == 3)	/* no 24bit packed */
@@ -562,13 +560,7 @@ static int psbfb_probe(struct drm_fb_helper *helper,
                 sizes->surface_depth = 16;
         }
 
-	if (!helper->fb) {
-		ret = psbfb_create(psb_fbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
+	return psbfb_create(psb_fbdev, sizes);
 }
 
 static struct drm_fb_helper_funcs psb_fb_helper_funcs = {
@@ -616,6 +608,10 @@ int psb_fbdev_init(struct drm_device *dev)
 							INTELFB_CONN_LIMIT);
 
 	drm_fb_helper_single_add_all_connectors(&fbdev->psb_fb_helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	drm_fb_helper_initial_config(&fbdev->psb_fb_helper, 32);
 	return 0;
 }

drivers/gpu/drm/i915/intel_crt.c

@@ -685,7 +685,6 @@ static void intel_crt_reset(struct drm_connector *connector)
 static const struct drm_encoder_helper_funcs crt_encoder_funcs = {
 	.mode_fixup = intel_crt_mode_fixup,
 	.mode_set = intel_crt_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_crt_connector_funcs = {

drivers/gpu/drm/i915/intel_ddi.c

@@ -1481,7 +1481,6 @@ static const struct drm_encoder_funcs intel_ddi_funcs = {
 static const struct drm_encoder_helper_funcs intel_ddi_helper_funcs = {
 	.mode_fixup = intel_ddi_mode_fixup,
 	.mode_set = intel_ddi_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 void intel_ddi_init(struct drm_device *dev, enum port port)

drivers/gpu/drm/i915/intel_display.c

@@ -3718,10 +3718,6 @@ void intel_crtc_update_dpms(struct drm_crtc *crtc)
 	intel_crtc_update_sarea(crtc, enable);
 }
 
-static void intel_crtc_noop(struct drm_crtc *crtc)
-{
-}
-
 static void intel_crtc_disable(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
@@ -3770,10 +3766,6 @@ void intel_modeset_disable(struct drm_device *dev)
 	}
 }
 
-void intel_encoder_noop(struct drm_encoder *encoder)
-{
-}
-
 void intel_encoder_destroy(struct drm_encoder *encoder)
 {
 	struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
@@ -7277,7 +7269,6 @@ free_work:
 static struct drm_crtc_helper_funcs intel_helper_funcs = {
 	.mode_set_base_atomic = intel_pipe_set_base_atomic,
 	.load_lut = intel_crtc_load_lut,
-	.disable = intel_crtc_noop,
 };
 
 bool intel_encoder_check_is_cloned(struct intel_encoder *encoder)
@@ -7987,14 +7978,9 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 	BUG_ON(!set->crtc);
 	BUG_ON(!set->crtc->helper_private);
 
-	if (!set->mode)
-		set->fb = NULL;
-
-	/* The fb helper likes to play gross jokes with ->mode_set_config.
-	 * Unfortunately the crtc helper doesn't do much at all for this case,
-	 * so we have to cope with this madness until the fb helper is fixed up. */
-	if (set->fb && set->num_connectors == 0)
-		return 0;
+	/* Enforce sane interface api - has been abused by the fb helper. */
+	BUG_ON(!set->mode && set->fb);
+	BUG_ON(set->fb && set->num_connectors == 0);
 
 	if (set->fb) {
 		DRM_DEBUG_KMS("[CRTC:%d] [FB:%d] #connectors=%d (x y) (%i %i)\n",

drivers/gpu/drm/i915/intel_dp.c

@@ -2561,7 +2561,6 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
 static const struct drm_encoder_helper_funcs intel_dp_helper_funcs = {
 	.mode_fixup = intel_dp_mode_fixup,
 	.mode_set = intel_dp_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_dp_connector_funcs = {

drivers/gpu/drm/i915/intel_drv.h

@@ -521,7 +521,6 @@ extern void intel_modeset_disable(struct drm_device *dev);
 extern void intel_crtc_restore_mode(struct drm_crtc *crtc);
 extern void intel_crtc_load_lut(struct drm_crtc *crtc);
 extern void intel_crtc_update_dpms(struct drm_crtc *crtc);
-extern void intel_encoder_noop(struct drm_encoder *encoder);
 extern void intel_encoder_destroy(struct drm_encoder *encoder);
 extern void intel_encoder_dpms(struct intel_encoder *encoder, int mode);
 extern bool intel_encoder_check_is_cloned(struct intel_encoder *encoder);

drivers/gpu/drm/i915/intel_dvo.c

@@ -345,7 +345,6 @@ static void intel_dvo_destroy(struct drm_connector *connector)
 static const struct drm_encoder_helper_funcs intel_dvo_helper_funcs = {
 	.mode_fixup = intel_dvo_mode_fixup,
 	.mode_set = intel_dvo_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_dvo_connector_funcs = {

drivers/gpu/drm/i915/intel_fb.c

@@ -57,9 +57,10 @@ static struct fb_ops intelfb_ops = {
 	.fb_debug_leave = drm_fb_helper_debug_leave,
 };
 
-static int intelfb_create(struct intel_fbdev *ifbdev,
+static int intelfb_create(struct drm_fb_helper *helper,
 			  struct drm_fb_helper_surface_size *sizes)
 {
+	struct intel_fbdev *ifbdev = (struct intel_fbdev *)helper;
 	struct drm_device *dev = ifbdev->helper.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct fb_info *info;
@@ -181,26 +182,10 @@ out:
 	return ret;
 }
 
-static int intel_fb_find_or_create_single(struct drm_fb_helper *helper,
-					  struct drm_fb_helper_surface_size *sizes)
-{
-	struct intel_fbdev *ifbdev = (struct intel_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = intelfb_create(ifbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static struct drm_fb_helper_funcs intel_fb_helper_funcs = {
 	.gamma_set = intel_crtc_fb_gamma_set,
 	.gamma_get = intel_crtc_fb_gamma_get,
-	.fb_probe = intel_fb_find_or_create_single,
+	.fb_probe = intelfb_create,
 };
 
 static void intel_fbdev_destroy(struct drm_device *dev,

drivers/gpu/drm/i915/intel_hdmi.c

@@ -972,7 +972,6 @@ static void intel_hdmi_destroy(struct drm_connector *connector)
 static const struct drm_encoder_helper_funcs intel_hdmi_helper_funcs = {
 	.mode_fixup = intel_hdmi_mode_fixup,
 	.mode_set = intel_hdmi_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_hdmi_connector_funcs = {

drivers/gpu/drm/i915/intel_lvds.c

@@ -656,7 +656,6 @@ static int intel_lvds_set_property(struct drm_connector *connector,
 static const struct drm_encoder_helper_funcs intel_lvds_helper_funcs = {
 	.mode_fixup = intel_lvds_mode_fixup,
 	.mode_set = intel_lvds_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_helper_funcs intel_lvds_connector_helper_funcs = {

drivers/gpu/drm/i915/intel_sdvo.c

@@ -2043,7 +2043,6 @@ done:
 static const struct drm_encoder_helper_funcs intel_sdvo_helper_funcs = {
 	.mode_fixup = intel_sdvo_mode_fixup,
 	.mode_set = intel_sdvo_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_sdvo_connector_funcs = {

drivers/gpu/drm/i915/intel_tv.c

@@ -1487,7 +1487,6 @@ out:
 static const struct drm_encoder_helper_funcs intel_tv_helper_funcs = {
 	.mode_fixup = intel_tv_mode_fixup,
 	.mode_set = intel_tv_mode_set,
-	.disable = intel_encoder_noop,
 };
 
 static const struct drm_connector_funcs intel_tv_connector_funcs = {

drivers/gpu/drm/mgag200/mgag200_fb.c

@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <drm/drmP.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_crtc_helper.h>
 
 #include <linux/fb.h>
 
@@ -120,9 +121,10 @@ static int mgag200fb_create_object(struct mga_fbdev *afbdev,
 	return ret;
 }
 
-static int mgag200fb_create(struct mga_fbdev *mfbdev,
+static int mgag200fb_create(struct drm_fb_helper *helper,
 			   struct drm_fb_helper_surface_size *sizes)
 {
+	struct mga_fbdev *mfbdev = (struct mga_fbdev *)helper;
 	struct drm_device *dev = mfbdev->helper.dev;
 	struct drm_mode_fb_cmd2 mode_cmd;
 	struct mga_device *mdev = dev->dev_private;
@@ -209,23 +211,6 @@ out:
 	return ret;
 }
 
-static int mga_fb_find_or_create_single(struct drm_fb_helper *helper,
-					   struct drm_fb_helper_surface_size
-					   *sizes)
-{
-	struct mga_fbdev *mfbdev = (struct mga_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = mgag200fb_create(mfbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static int mga_fbdev_destroy(struct drm_device *dev,
 				struct mga_fbdev *mfbdev)
 {
@@ -256,7 +241,7 @@ static int mga_fbdev_destroy(struct drm_device *dev,
 static struct drm_fb_helper_funcs mga_fb_helper_funcs = {
 	.gamma_set = mga_crtc_fb_gamma_set,
 	.gamma_get = mga_crtc_fb_gamma_get,
-	.fb_probe = mga_fb_find_or_create_single,
+	.fb_probe = mgag200fb_create,
 };
 
 int mgag200_fbdev_init(struct mga_device *mdev)
@@ -278,6 +263,10 @@ int mgag200_fbdev_init(struct mga_device *mdev)
 		return ret;
 	}
 	drm_fb_helper_single_add_all_connectors(&mfbdev->helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(mdev->dev);
+
 	drm_fb_helper_initial_config(&mfbdev->helper, 32);
 
 	return 0;

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -251,9 +251,10 @@ nouveau_fbcon_zfill(struct drm_device *dev, struct nouveau_fbdev *fbcon)
 }
 
 static int
-nouveau_fbcon_create(struct nouveau_fbdev *fbcon,
+nouveau_fbcon_create(struct drm_fb_helper *helper,
 		     struct drm_fb_helper_surface_size *sizes)
 {
+	struct nouveau_fbdev *fbcon = (struct nouveau_fbdev *)helper;
 	struct drm_device *dev = fbcon->dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_device *device = nv_device(drm->device);
@@ -388,23 +389,6 @@ out:
 	return ret;
 }
 
-static int
-nouveau_fbcon_find_or_create_single(struct drm_fb_helper *helper,
-				    struct drm_fb_helper_surface_size *sizes)
-{
-	struct nouveau_fbdev *fbcon = (struct nouveau_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = nouveau_fbcon_create(fbcon, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 void
 nouveau_fbcon_output_poll_changed(struct drm_device *dev)
 {
@@ -450,7 +434,7 @@ void nouveau_fbcon_gpu_lockup(struct fb_info *info)
 static struct drm_fb_helper_funcs nouveau_fbcon_helper_funcs = {
 	.gamma_set = nouveau_fbcon_gamma_set,
 	.gamma_get = nouveau_fbcon_gamma_get,
-	.fb_probe = nouveau_fbcon_find_or_create_single,
+	.fb_probe = nouveau_fbcon_create,
 };
 
 
@@ -491,6 +475,9 @@ nouveau_fbcon_init(struct drm_device *dev)
 	else
 		preferred_bpp = 32;
 
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	drm_fb_helper_initial_config(&fbcon->helper, preferred_bpp);
 	return 0;
 }

drivers/gpu/drm/radeon/radeon_fb.c

@@ -187,9 +187,10 @@ out_unref:
 	return ret;
 }
 
-static int radeonfb_create(struct radeon_fbdev *rfbdev,
+static int radeonfb_create(struct drm_fb_helper *helper,
 			   struct drm_fb_helper_surface_size *sizes)
 {
+	struct radeon_fbdev *rfbdev = (struct radeon_fbdev *)helper;
 	struct radeon_device *rdev = rfbdev->rdev;
 	struct fb_info *info;
 	struct drm_framebuffer *fb = NULL;
@@ -300,22 +301,6 @@ out_unref:
 	return ret;
 }
 
-static int radeon_fb_find_or_create_single(struct drm_fb_helper *helper,
-					   struct drm_fb_helper_surface_size *sizes)
-{
-	struct radeon_fbdev *rfbdev = (struct radeon_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = radeonfb_create(rfbdev, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 void radeon_fb_output_poll_changed(struct radeon_device *rdev)
 {
 	drm_fb_helper_hotplug_event(&rdev->mode_info.rfbdev->helper);
@@ -349,7 +334,7 @@ static int radeon_fbdev_destroy(struct drm_device *dev, struct radeon_fbdev *rfb
 static struct drm_fb_helper_funcs radeon_fb_helper_funcs = {
 	.gamma_set = radeon_crtc_fb_gamma_set,
 	.gamma_get = radeon_crtc_fb_gamma_get,
-	.fb_probe = radeon_fb_find_or_create_single,
+	.fb_probe = radeonfb_create,
 };
 
 int radeon_fbdev_init(struct radeon_device *rdev)
@@ -379,6 +364,10 @@ int radeon_fbdev_init(struct radeon_device *rdev)
 	}
 
 	drm_fb_helper_single_add_all_connectors(&rfbdev->helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(rdev->ddev);
+
 	drm_fb_helper_initial_config(&rfbdev->helper, bpp_sel);
 	return 0;
 }

drivers/gpu/drm/tegra/fb.c

@@ -39,10 +39,6 @@ int tegra_drm_fb_init(struct drm_device *drm)
 	if (IS_ERR(fbdev))
 		return PTR_ERR(fbdev);
 
-#ifndef CONFIG_FRAMEBUFFER_CONSOLE
-	drm_fbdev_cma_restore_mode(fbdev);
-#endif
-
 	host1x->fbdev = fbdev;
 
 	return 0;

drivers/gpu/drm/udl/udl_fb.c

@@ -476,9 +476,10 @@ udl_framebuffer_init(struct drm_device *dev,
 }
 
 
-static int udlfb_create(struct udl_fbdev *ufbdev,
+static int udlfb_create(struct drm_fb_helper *helper,
 			struct drm_fb_helper_surface_size *sizes)
 {
+	struct udl_fbdev *ufbdev = (struct udl_fbdev *)helper;
 	struct drm_device *dev = ufbdev->helper.dev;
 	struct fb_info *info;
 	struct device *device = &dev->usbdev->dev;
@@ -556,27 +557,10 @@ out:
 	return ret;
 }
 
-static int udl_fb_find_or_create_single(struct drm_fb_helper *helper,
-					struct drm_fb_helper_surface_size *sizes)
-{
-	struct udl_fbdev *ufbdev = (struct udl_fbdev *)helper;
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = udlfb_create(ufbdev, sizes);
-		if (ret)
-			return ret;
-
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static struct drm_fb_helper_funcs udl_fb_helper_funcs = {
 	.gamma_set = udl_crtc_fb_gamma_set,
 	.gamma_get = udl_crtc_fb_gamma_get,
-	.fb_probe = udl_fb_find_or_create_single,
+	.fb_probe = udlfb_create,
 };
 
 static void udl_fbdev_destroy(struct drm_device *dev,
@@ -619,6 +603,10 @@ int udl_fbdev_init(struct drm_device *dev)
 	}
 
 	drm_fb_helper_single_add_all_connectors(&ufbdev->helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	drm_fb_helper_initial_config(&ufbdev->helper, bpp_sel);
 	return 0;
 }

drivers/staging/omapdrm/omap_fbdev.c

@@ -296,25 +296,10 @@ static void omap_crtc_fb_gamma_get(struct drm_crtc *crtc,
 	DBG("fbdev: get gamma");
 }
 
-static int omap_fbdev_probe(struct drm_fb_helper *helper,
-		struct drm_fb_helper_surface_size *sizes)
-{
-	int new_fb = 0;
-	int ret;
-
-	if (!helper->fb) {
-		ret = omap_fbdev_create(helper, sizes);
-		if (ret)
-			return ret;
-		new_fb = 1;
-	}
-	return new_fb;
-}
-
 static struct drm_fb_helper_funcs omap_fb_helper_funcs = {
 	.gamma_set = omap_crtc_fb_gamma_set,
 	.gamma_get = omap_crtc_fb_gamma_get,
-	.fb_probe = omap_fbdev_probe,
+	.fb_probe = omap_fbdev_create,
 };
 
 static struct drm_fb_helper *get_fb(struct fb_info *fbi)
@@ -369,6 +354,10 @@ struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev)
 	}
 
 	drm_fb_helper_single_add_all_connectors(helper);
+
+	/* disable all the possible outputs/crtcs before entering KMS mode */
+	drm_helper_disable_unused_functions(dev);
+
 	drm_fb_helper_initial_config(helper, 32);
 
 	priv->fbdev = helper;

include/drm/drm_crtc.h

@@ -867,6 +867,7 @@ struct drm_prop_enum_list {
 
 extern void drm_modeset_lock_all(struct drm_device *dev);
 extern void drm_modeset_unlock_all(struct drm_device *dev);
+extern void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
 
 extern int drm_crtc_init(struct drm_device *dev,
 			 struct drm_crtc *crtc,

include/drm/drm_fb_helper.h

@@ -48,6 +48,18 @@ struct drm_fb_helper_surface_size {
 	u32 surface_depth;
 };
 
+/**
+ * struct drm_fb_helper_funcs - driver callbacks for the fbdev emulation library
+ * @gamma_set: - Set the given gamma lut register on the given crtc.
+ * @gamma_get: - Read the given gamma lut register on the given crtc, used to
+ * 		 save the current lut when force-restoring the fbdev for e.g.
+ * 		 kdbg.
+ * @fb_probe: - Driver callback to allocate and initialize the fbdev info
+ * 		structure. Futhermore it also needs to allocate the drm
+ * 		framebuffer used to back the fbdev.
+ *
+ * Driver callbacks used by the fbdev emulation helper library.
+ */
 struct drm_fb_helper_funcs {
 	void (*gamma_set)(struct drm_crtc *crtc, u16 red, u16 green,
 			  u16 blue, int regno);
@@ -65,9 +77,7 @@ struct drm_fb_helper_connector {
 
 struct drm_fb_helper {
 	struct drm_framebuffer *fb;
-	struct drm_framebuffer *saved_fb;
 	struct drm_device *dev;
-	struct drm_display_mode *mode;
 	int crtc_count;
 	struct drm_fb_helper_crtc *crtc_info;
 	int connector_count;
@@ -82,9 +92,6 @@ struct drm_fb_helper {
 	bool delayed_hotplug;
 };
 
-int drm_fb_helper_single_fb_probe(struct drm_fb_helper *helper,
-				  int preferred_bpp);
-
 int drm_fb_helper_init(struct drm_device *dev,
 		       struct drm_fb_helper *helper, int crtc_count,
 		       int max_conn);
@@ -103,7 +110,6 @@ int drm_fb_helper_setcolreg(unsigned regno,
 			    struct fb_info *info);
 
 bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper);
-void drm_fb_helper_restore(void);
 void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
 			    uint32_t fb_width, uint32_t fb_height);
 void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,