drm/fb-helper: Remove drm_fb_helper_crtc

struct drm_fb_helper_crtc is now just a wrapper around drm_mode_set so
use that directly instead and attach it as a modeset array onto
drm_client_dev. drm_fb_helper will use this array to store its modesets
which means it will always initialize a drm_client, but it will not
register the client (callbacks) unless it's the generic fbdev emulation.

Code will later be moved to drm_client, so add code there in a new file
drm_client_modeset.c with MIT license to match drm_fb_helper.c.

The modeset connector array size is hardcoded for the cloned case to avoid
having to pass in a value from the driver. A value of 8 is chosen to err
on the safe side. This means that the max connector argument for
drm_fb_helper_init() and drm_fb_helper_fbdev_setup() isn't used anymore,
a todo entry for this is added.

In pan_display_atomic() restore_fbdev_mode_force() is used instead of
restore_fbdev_mode_atomic() because that one will later become internal
to drm_client_modeset.

Locking order:
1. drm_fb_helper->lock
2. drm_master_internal_acquire
3. drm_client_dev->modeset_mutex

v6: Improve commit message (Sam Ravnborg)

v3:
- Use full drm_client_init/release for the modesets (Daniel Vetter)
- drm_client_for_each_modeset: use lockdep_assert_held (Daniel Vetter)
- Hook up to Documentation/gpu/drm-client.rst (Daniel Vetter)

v2:
- Add modesets array to drm_client (Daniel Vetter)
- Use a new file for the modeset code (Daniel Vetter)
- File has to be MIT licensed (Emmanuel Vadot)
- Add copyrights from drm_fb_helper.c

Signed-off-by: Noralf Trønnes <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/gpu/drm-client.rst

···
 
 .. kernel-doc:: drivers/gpu/drm/drm_client.c
    :export:
+
+.. kernel-doc:: drivers/gpu/drm/drm_client_modeset.c
+   :export:

Documentation/gpu/todo.rst

···
   these igt tests need to be fixed: kms_fbcon_fbt@psr and
   kms_fbcon_fbt@psr-suspend.
 
+- The max connector argument for drm_fb_helper_init() and
+  drm_fb_helper_fbdev_setup() isn't used anymore and can be removed.
+
 Core refactorings
 =================
 

drivers/gpu/drm/Makefile

···
 		drm_plane.o drm_color_mgmt.o drm_print.o \
 		drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
 		drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
-		drm_atomic_uapi.o drm_hdcp.o
+		drm_client_modeset.o drm_atomic_uapi.o drm_hdcp.o
 
 drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o drm_dma.o drm_scatter.o drm_lock.o
 drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o

drivers/gpu/drm/drm_client.c

···
  * DOC: overview
  *
  * This library provides support for clients running in the kernel like fbdev and bootsplash.
- * Currently it's only partially implemented, just enough to support fbdev.
  *
  * GEM drivers which provide a GEM based dumb buffer with a virtual address are supported.
  */
···
 	client->name = name;
 	client->funcs = funcs;
 
-	ret = drm_client_open(client);
+	ret = drm_client_modeset_create(client);
 	if (ret)
 		goto err_put_module;
+
+	ret = drm_client_open(client);
+	if (ret)
+		goto err_free;
 
 	drm_dev_get(dev);
 
 	return 0;
 
+err_free:
+	drm_client_modeset_free(client);
 err_put_module:
 	if (funcs)
 		module_put(funcs->owner);
···
 
 	DRM_DEV_DEBUG_KMS(dev->dev, "%s\n", client->name);
 
+	drm_client_modeset_free(client);
 	drm_client_close(client);
 	drm_dev_put(dev);
 	if (client->funcs)

drivers/gpu/drm/drm_client_modeset.c

···
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2018 Noralf Trønnes
+ * Copyright (c) 2006-2009 Red Hat Inc.
+ * Copyright (c) 2006-2008 Intel Corporation
+ *   Jesse Barnes <[e-mail]>
+ * Copyright (c) 2007 Dave Airlie <[e-mail]>
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_device.h>
+
+int drm_client_modeset_create(struct drm_client_dev *client)
+{
+	struct drm_device *dev = client->dev;
+	unsigned int num_crtc = dev->mode_config.num_crtc;
+	unsigned int max_connector_count = 1;
+	struct drm_mode_set *modeset;
+	struct drm_crtc *crtc;
+	unsigned int i = 0;
+
+	/* Add terminating zero entry to enable index less iteration */
+	client->modesets = kcalloc(num_crtc + 1, sizeof(*client->modesets), GFP_KERNEL);
+	if (!client->modesets)
+		return -ENOMEM;
+
+	mutex_init(&client->modeset_mutex);
+
+	drm_for_each_crtc(crtc, dev)
+		client->modesets[i++].crtc = crtc;
+
+	/* Cloning is only supported in the single crtc case. */
+	if (num_crtc == 1)
+		max_connector_count = DRM_CLIENT_MAX_CLONED_CONNECTORS;
+
+	for (modeset = client->modesets; modeset->crtc; modeset++) {
+		modeset->connectors = kcalloc(max_connector_count,
+					      sizeof(*modeset->connectors), GFP_KERNEL);
+		if (!modeset->connectors)
+			goto err_free;
+	}
+
+	return 0;
+
+err_free:
+	drm_client_modeset_free(client);
+
+	return -ENOMEM;
+}
+
+void drm_client_modeset_release(struct drm_client_dev *client)
+{
+	struct drm_mode_set *modeset;
+	unsigned int i;
+
+	drm_client_for_each_modeset(modeset, client) {
+		drm_mode_destroy(client->dev, modeset->mode);
+		modeset->mode = NULL;
+		modeset->fb = NULL;
+
+		for (i = 0; i < modeset->num_connectors; i++) {
+			drm_connector_put(modeset->connectors[i]);
+			modeset->connectors[i] = NULL;
+		}
+		modeset->num_connectors = 0;
+	}
+}
+/* TODO: Remove export when modeset code has been moved over */
+EXPORT_SYMBOL(drm_client_modeset_release);
+
+void drm_client_modeset_free(struct drm_client_dev *client)
+{
+	struct drm_mode_set *modeset;
+
+	mutex_lock(&client->modeset_mutex);
+
+	drm_client_modeset_release(client);
+
+	drm_client_for_each_modeset(modeset, client)
+		kfree(modeset->connectors);
+
+	mutex_unlock(&client->modeset_mutex);
+
+	mutex_destroy(&client->modeset_mutex);
+	kfree(client->modesets);
+}
+
+struct drm_mode_set *drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc)
+{
+	struct drm_mode_set *modeset;
+
+	drm_client_for_each_modeset(modeset, client)
+		if (modeset->crtc == crtc)
+			return modeset;
+
+	return NULL;
+}
+/* TODO: Remove export when modeset code has been moved over */
+EXPORT_SYMBOL(drm_client_find_modeset);

drivers/gpu/drm/drm_fb_helper.c

···
 {
 	struct drm_fb_helper *helper = info->par;
 	const struct drm_crtc_helper_funcs *funcs;
-	int i;
+	struct drm_mode_set *mode_set;
 
 	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
-		for (i = 0; i < helper->crtc_count; i++) {
-			struct drm_mode_set *mode_set =
-				&helper->crtc_info[i].mode_set;
-
+		mutex_lock(&helper->client.modeset_mutex);
+		drm_client_for_each_modeset(mode_set, &helper->client) {
 			if (!mode_set->crtc->enabled)
 				continue;
 
···
 						    mode_set->y,
 						    ENTER_ATOMIC_MODE_SET);
 		}
+		mutex_unlock(&helper->client.modeset_mutex);
 	}
 
 	return 0;
···
 int drm_fb_helper_debug_leave(struct fb_info *info)
 {
 	struct drm_fb_helper *helper = info->par;
+	struct drm_client_dev *client = &helper->client;
 	struct drm_crtc *crtc;
 	const struct drm_crtc_helper_funcs *funcs;
+	struct drm_mode_set *mode_set;
 	struct drm_framebuffer *fb;
-	int i;
 
-	for (i = 0; i < helper->crtc_count; i++) {
-		struct drm_mode_set *mode_set = &helper->crtc_info[i].mode_set;
-
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(mode_set, client) {
 		crtc = mode_set->crtc;
 		if (drm_drv_uses_atomic_modeset(crtc->dev))
 			continue;
···
 		funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
 					    crtc->y, LEAVE_ATOMIC_MODE_SET);
 	}
+	mutex_unlock(&client->modeset_mutex);
 
 	return 0;
 }
···
 
 static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool active)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
 	struct drm_plane_state *plane_state;
 	struct drm_plane *plane;
 	struct drm_atomic_state *state;
-	int i, ret;
 	struct drm_modeset_acquire_ctx ctx;
+	struct drm_mode_set *mode_set;
+	int ret;
 
 	drm_modeset_acquire_init(&ctx, 0);
 
···
 			goto out_state;
 	}
 
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
+	drm_client_for_each_modeset(mode_set, client) {
 		struct drm_plane *primary = mode_set->crtc->primary;
 		unsigned int rotation;
 
···
 
 static int restore_fbdev_mode_legacy(struct drm_fb_helper *fb_helper)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
+	struct drm_mode_set *mode_set;
 	struct drm_plane *plane;
-	int i, ret = 0;
+	int ret = 0;
 
 	drm_modeset_lock_all(fb_helper->dev);
 	drm_for_each_plane(plane, dev) {
···
 						    DRM_MODE_ROTATE_0);
 	}
 
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
+	drm_client_for_each_modeset(mode_set, client) {
 		struct drm_crtc *crtc = mode_set->crtc;
 
 		if (crtc->funcs->cursor_set2) {
···
 static int restore_fbdev_mode_force(struct drm_fb_helper *fb_helper)
 {
 	struct drm_device *dev = fb_helper->dev;
+	int ret;
 
+	mutex_lock(&fb_helper->client.modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
-		return restore_fbdev_mode_atomic(fb_helper, true);
+		ret = restore_fbdev_mode_atomic(fb_helper, true);
 	else
-		return restore_fbdev_mode_legacy(fb_helper);
+		ret = restore_fbdev_mode_legacy(fb_helper);
+	mutex_unlock(&fb_helper->client.modeset_mutex);
+
+	return ret;
 }
 
 static int restore_fbdev_mode(struct drm_fb_helper *fb_helper)
···
 
 static void dpms_legacy(struct drm_fb_helper *fb_helper, int dpms_mode)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
 	struct drm_connector *connector;
 	struct drm_mode_set *modeset;
-	int i, j;
+	int j;
 
 	drm_modeset_lock_all(dev);
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		modeset = &fb_helper->crtc_info[i].mode_set;
-
+	drm_client_for_each_modeset(modeset, client) {
 		if (!modeset->crtc->enabled)
 			continue;
 
···
 static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
 {
 	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
 
 	/*
···
 	if (!drm_master_internal_acquire(dev))
 		goto unlock;
 
+	mutex_lock(&client->modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
 		restore_fbdev_mode_atomic(fb_helper, dpms_mode == DRM_MODE_DPMS_ON);
 	else
 		dpms_legacy(fb_helper, dpms_mode);
+	mutex_unlock(&client->modeset_mutex);
 
 	drm_master_internal_release(dev);
 unlock:
···
 	return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_blank);
-
-static void drm_fb_helper_modeset_release(struct drm_fb_helper *helper,
-					  struct drm_mode_set *modeset)
-{
-	int i;
-
-	for (i = 0; i < modeset->num_connectors; i++) {
-		drm_connector_put(modeset->connectors[i]);
-		modeset->connectors[i] = NULL;
-	}
-	modeset->num_connectors = 0;
-
-	drm_mode_destroy(helper->dev, modeset->mode);
-	modeset->mode = NULL;
-
-	/* FIXME should hold a ref? */
-	modeset->fb = NULL;
-}
-
-static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
-{
-	int i;
-
-	for (i = 0; i < helper->connector_count; i++) {
-		drm_connector_put(helper->connector_info[i]->connector);
-		kfree(helper->connector_info[i]);
-	}
-	kfree(helper->connector_info);
-
-	for (i = 0; i < helper->crtc_count; i++) {
-		struct drm_mode_set *modeset = &helper->crtc_info[i].mode_set;
-
-		drm_fb_helper_modeset_release(helper, modeset);
-		kfree(modeset->connectors);
-	}
-	kfree(helper->crtc_info);
-}
 
 static void drm_fb_helper_resume_worker(struct work_struct *work)
 {
···
  * drm_fb_helper_init - initialize a &struct drm_fb_helper
  * @dev: drm device
  * @fb_helper: driver-allocated fbdev helper structure to initialize
- * @max_conn_count: max connector count
+ * @max_conn_count: max connector count (not used)
  *
  * 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)
···
 		       struct drm_fb_helper *fb_helper,
 		       int max_conn_count)
 {
-	struct drm_crtc *crtc;
-	struct drm_mode_config *config = &dev->mode_config;
-	int i;
+	int ret;
 
 	if (!drm_fbdev_emulation) {
 		dev->fb_helper = fb_helper;
 		return 0;
 	}
 
-	if (!max_conn_count)
-		return -EINVAL;
-
-	fb_helper->crtc_info = kcalloc(config->num_crtc, sizeof(struct drm_fb_helper_crtc), GFP_KERNEL);
-	if (!fb_helper->crtc_info)
-		return -ENOMEM;
-
-	fb_helper->crtc_count = config->num_crtc;
-	fb_helper->connector_info = kcalloc(dev->mode_config.num_connector, sizeof(struct drm_fb_helper_connector *), GFP_KERNEL);
-	if (!fb_helper->connector_info) {
-		kfree(fb_helper->crtc_info);
-		return -ENOMEM;
+	/*
+	 * If this is not the generic fbdev client, initialize a drm_client
+	 * without callbacks so we can use the modesets.
+	 */
+	if (!fb_helper->client.funcs) {
+		ret = drm_client_init(dev, &fb_helper->client, "drm_fb_helper", NULL);
+		if (ret)
+			return ret;
 	}
+
+	fb_helper->connector_info = kcalloc(dev->mode_config.num_connector, sizeof(struct drm_fb_helper_connector *), GFP_KERNEL);
+	if (!fb_helper->connector_info)
+		goto out_free;
+
 	fb_helper->connector_info_alloc_count = dev->mode_config.num_connector;
 	fb_helper->connector_count = 0;
-
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		fb_helper->crtc_info[i].mode_set.connectors =
-			kcalloc(max_conn_count,
-				sizeof(struct drm_connector *),
-				GFP_KERNEL);
-
-		if (!fb_helper->crtc_info[i].mode_set.connectors)
-			goto out_free;
-		fb_helper->crtc_info[i].mode_set.num_connectors = 0;
-	}
-
-	i = 0;
-	drm_for_each_crtc(crtc, dev) {
-		fb_helper->crtc_info[i].mode_set.crtc = crtc;
-		i++;
-	}
 
 	dev->fb_helper = fb_helper;
 
 	return 0;
 out_free:
-	drm_fb_helper_crtc_free(fb_helper);
+	drm_client_release(&fb_helper->client);
+
 	return -ENOMEM;
 }
 EXPORT_SYMBOL(drm_fb_helper_init);
···
 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 {
 	struct fb_info *info;
+	int i;
 
 	if (!fb_helper)
 		return;
···
 	mutex_unlock(&kernel_fb_helper_lock);
 
 	mutex_destroy(&fb_helper->lock);
-	drm_fb_helper_crtc_free(fb_helper);
 
+	if (!fb_helper->client.funcs)
+		drm_client_release(&fb_helper->client);
+
+	for (i = 0; i < fb_helper->connector_count; i++) {
+		drm_connector_put(fb_helper->connector_info[i]->connector);
+		kfree(fb_helper->connector_info[i]);
+	}
+	kfree(fb_helper->connector_info);
 }
 EXPORT_SYMBOL(drm_fb_helper_fini);
 
···
 static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_mode_set *modeset;
 	struct drm_crtc *crtc;
 	u16 *r, *g, *b;
-	int i, ret = 0;
+	int ret = 0;
 
 	drm_modeset_lock_all(fb_helper->dev);
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		crtc = fb_helper->crtc_info[i].mode_set.crtc;
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
 		if (!crtc->funcs->gamma_set || !crtc->gamma_size)
 			return -EINVAL;
 
···
 	struct drm_modeset_acquire_ctx ctx;
 	struct drm_crtc_state *crtc_state;
 	struct drm_atomic_state *state;
+	struct drm_mode_set *modeset;
 	struct drm_crtc *crtc;
 	u16 *r, *g, *b;
-	int i, ret = 0;
 	bool replaced;
+	int ret = 0;
 
 	drm_modeset_acquire_init(&ctx, 0);
 
···
 
 	state->acquire_ctx = &ctx;
 retry:
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		crtc = fb_helper->crtc_info[i].mode_set.crtc;
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
 
 		if (!gamma_lut)
 			gamma_lut = setcmap_new_gamma_lut(crtc, cmap);
···
 	if (ret)
 		goto out_state;
 
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		crtc = fb_helper->crtc_info[i].mode_set.crtc;
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
 
 		r = crtc->gamma_store;
 		g = r + crtc->gamma_size;
···
 		goto unlock;
 	}
 
+	mutex_lock(&fb_helper->client.modeset_mutex);
 	if (info->fix.visual == FB_VISUAL_TRUECOLOR)
 		ret = setcmap_pseudo_palette(cmap, info);
 	else if (drm_drv_uses_atomic_modeset(fb_helper->dev))
 		ret = setcmap_atomic(cmap, info);
 	else
 		ret = setcmap_legacy(cmap, info);
+	mutex_unlock(&fb_helper->client.modeset_mutex);
 
 	drm_master_internal_release(dev);
 unlock:
···
 {
 	struct drm_fb_helper *fb_helper = info->par;
 	struct drm_device *dev = fb_helper->dev;
-	struct drm_mode_set *mode_set;
 	struct drm_crtc *crtc;
 	int ret = 0;
 
···
 		 * make. If we're not smart enough here, one should
 		 * just consider switch the userspace to KMS.
 		 */
-		mode_set = &fb_helper->crtc_info[0].mode_set;
-		crtc = mode_set->crtc;
+		crtc = fb_helper->client.modesets[0].crtc;
 
 		/*
 		 * Only wait for a vblank event if the CRTC is
···
 
 static void pan_set(struct drm_fb_helper *fb_helper, int x, int y)
 {
-	int i;
+	struct drm_mode_set *mode_set;
 
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		struct drm_mode_set *mode_set;
-
-		mode_set = &fb_helper->crtc_info[i].mode_set;
-
+	mutex_lock(&fb_helper->client.modeset_mutex);
+	drm_client_for_each_modeset(mode_set, &fb_helper->client) {
 		mode_set->x = x;
 		mode_set->y = y;
 	}
+	mutex_unlock(&fb_helper->client.modeset_mutex);
 }
 
 static int pan_display_atomic(struct fb_var_screeninfo *var,
···
 
 	pan_set(fb_helper, var->xoffset, var->yoffset);
 
-	ret = restore_fbdev_mode_atomic(fb_helper, true);
+	ret = restore_fbdev_mode_force(fb_helper);
 	if (!ret) {
 		info->var.xoffset = var->xoffset;
 		info->var.yoffset = var->yoffset;
···
 			      struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_mode_set *modeset;
 	int ret = 0;
-	int i;
 
 	drm_modeset_lock_all(fb_helper->dev);
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		modeset = &fb_helper->crtc_info[i].mode_set;
-
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(modeset, client) {
 		modeset->x = var->xoffset;
 		modeset->y = var->yoffset;
 
···
 			}
 		}
 	}
+	mutex_unlock(&client->modeset_mutex);
 	drm_modeset_unlock_all(fb_helper->dev);
 
 	return ret;
···
 static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 					 int preferred_bpp)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	int ret = 0;
 	int crtc_count = 0;
 	int i;
 	struct drm_fb_helper_surface_size sizes;
+	struct drm_mode_set *mode_set;
 	int best_depth = 0;
 
 	memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
···
 	 * supports RGBA5551 (16 bpp, depth 15) but not RGB565 (16 bpp, depth
 	 * 16) we need to scale down the depth of the sizes we request.
 	 */
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(mode_set, client) {
 		struct drm_crtc *crtc = mode_set->crtc;
 		struct drm_plane *plane = crtc->primary;
 		int j;
 
-		DRM_DEBUG("test CRTC %d primary plane\n", i);
+		DRM_DEBUG("test CRTC %u primary plane\n", drm_crtc_index(crtc));
 
 		for (j = 0; j < plane->format_count; j++) {
 			const struct drm_format_info *fmt;
···
 
 	/* first up get a count of crtcs now in use and new min/maxes width/heights */
 	crtc_count = 0;
-	for (i = 0; i < fb_helper->crtc_count; i++) {
+	drm_client_for_each_modeset(mode_set, client) {
 		struct drm_display_mode *desired_mode;
-		struct drm_mode_set *mode_set;
 		int x, y, j;
 		/* in case of tile group, are we the last tile vert or horiz?
 		 * If no tile group you are always the last one both vertically
···
 		 */
 		bool lastv = true, lasth = true;
 
-		mode_set = &fb_helper->crtc_info[i].mode_set;
 		desired_mode = mode_set->mode;
 
 		if (!desired_mode)
···
 		if (lastv)
 			sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
 	}
+	mutex_unlock(&client->modeset_mutex);
 
 	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
 		DRM_INFO("Cannot find any crtc or sizes\n");
···
 	struct drm_display_mode *dmt_mode, *mode;
 
 	/* only contemplate cloning in the single crtc case */
-	if (fb_helper->crtc_count > 1)
+	if (fb_helper->dev->mode_config.num_crtc > 1)
 		return false;
 
 	count = 0;
···
 }
 
 static int drm_pick_crtcs(struct drm_fb_helper *fb_helper,
-			  struct drm_fb_helper_crtc **best_crtcs,
+			  struct drm_crtc **best_crtcs,
 			  struct drm_display_mode **modes,
 			  int n, int width, int height)
 {
-	int c, o;
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_connector *connector;
 	int my_score, best_score, score;
-	struct drm_fb_helper_crtc **crtcs, *crtc;
+	struct drm_crtc **crtcs, *crtc;
+	struct drm_mode_set *modeset;
 	struct drm_fb_helper_connector *fb_helper_conn;
+	int o;
 
 	if (n == fb_helper->connector_count)
 		return 0;
···
 	if (modes[n] == NULL)
 		return best_score;
 
-	crtcs = kcalloc(fb_helper->connector_count,
-			sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
+	crtcs = kcalloc(fb_helper->connector_count, sizeof(*crtcs), GFP_KERNEL);
 	if (!crtcs)
 		return best_score;
 
···
 	 * select a crtc for this connector and then attempt to configure
 	 * remaining connectors
 	 */
-	for (c = 0; c < fb_helper->crtc_count; c++) {
-		crtc = &fb_helper->crtc_info[c];
+	drm_client_for_each_modeset(modeset, client) {
+		crtc = modeset->crtc;
 
-		if (!connector_has_possible_crtc(connector,
-						 crtc->mode_set.crtc))
+		if (!connector_has_possible_crtc(connector, crtc))
 			continue;
 
 		for (o = 0; o < n; o++)
···
 
 		if (o < n) {
 			/* ignore cloning unless only a single crtc */
-			if (fb_helper->crtc_count > 1)
+			if (fb_helper->dev->mode_config.num_crtc > 1)
 				continue;
 
 			if (!drm_mode_equal(modes[o], modes[n]))
···
 		}
 
 		crtcs[n] = crtc;
-		memcpy(crtcs, best_crtcs, n * sizeof(struct drm_fb_helper_crtc *));
+		memcpy(crtcs, best_crtcs, n * sizeof(*crtcs));
 		score = my_score + drm_pick_crtcs(fb_helper, crtcs, modes, n + 1,
 						  width, height);
 		if (score > best_score) {
 			best_score = score;
 			memcpy(best_crtcs, crtcs,
-			       fb_helper->connector_count *
-			       sizeof(struct drm_fb_helper_crtc *));
+			       fb_helper->connector_count * sizeof(*crtcs));
 		}
 	}
 
···
 	return best_score;
 }
 
-static struct drm_fb_helper_crtc *
-drm_fb_helper_crtc(struct drm_fb_helper *fb_helper, struct drm_crtc *crtc)
-{
-	int i;
-
-	for (i = 0; i < fb_helper->crtc_count; i++)
-		if (fb_helper->crtc_info[i].mode_set.crtc == crtc)
-			return &fb_helper->crtc_info[i];
-
-	return NULL;
-}
-
 /* Try to read the BIOS display configuration and use it for the initial config */
 static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
-					  struct drm_fb_helper_crtc **crtcs,
+					  struct drm_crtc **crtcs,
 					  struct drm_display_mode **modes,
 					  struct drm_fb_offset *offsets,
 					  bool *enabled, int width, int height)
···
 		struct drm_fb_helper_connector *fb_conn;
 		struct drm_connector *connector;
 		struct drm_encoder *encoder;
-		struct drm_fb_helper_crtc *new_crtc;
+		struct drm_crtc *new_crtc;
 
 		fb_conn = fb_helper->connector_info[i];
 		connector = fb_conn->connector;
···
 
 		num_connectors_enabled++;
 
-		new_crtc = drm_fb_helper_crtc(fb_helper, connector->state->crtc);
+		new_crtc = connector->state->crtc;
 
 		/*
 		 * Make sure we're not trying to drive multiple connectors
···
 static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
 			    u32 width, u32 height)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
-	struct drm_fb_helper_crtc **crtcs;
 	struct drm_display_mode **modes;
 	struct drm_fb_offset *offsets;
+	struct drm_crtc **crtcs;
 	bool *enabled;
 	int i;
 
···
 	/* prevent concurrent modification of connector_count by hotplug */
 	lockdep_assert_held(&fb_helper->lock);
 
-	crtcs = kcalloc(fb_helper->connector_count,
-			sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
+	crtcs = kcalloc(fb_helper->connector_count, sizeof(*crtcs), GFP_KERNEL);
 	modes = kcalloc(fb_helper->connector_count,
 			sizeof(struct drm_display_mode *), GFP_KERNEL);
 	offsets = kcalloc(fb_helper->connector_count,
···
 		DRM_ERROR("Memory allocation failed\n");
 		goto out;
 	}
+
+	mutex_lock(&client->modeset_mutex);
 
 	mutex_lock(&fb_helper->dev->mode_config.mutex);
 	if (drm_fb_helper_probe_connector_modes(fb_helper, width, height) == 0)
···
 	}
 	mutex_unlock(&fb_helper->dev->mode_config.mutex);
 
-	/* need to set the modesets up here for use later */
-	/* fill out the connector<->crtc mappings into the modesets */
-	for (i = 0; i < fb_helper->crtc_count; i++)
-		drm_fb_helper_modeset_release(fb_helper,
-					      &fb_helper->crtc_info[i].mode_set);
+	drm_client_modeset_release(client);
 
 	drm_fb_helper_for_each_connector(fb_helper, i) {
 		struct drm_display_mode *mode = modes[i];
-		struct drm_fb_helper_crtc *fb_crtc = crtcs[i];
+		struct drm_crtc *crtc = crtcs[i];
 		struct drm_fb_offset *offset = &offsets[i];
 
-		if (mode && fb_crtc) {
-			struct drm_mode_set *modeset = &fb_crtc->mode_set;
+		if (mode && crtc) {
+			struct drm_mode_set *modeset = drm_client_find_modeset(client, crtc);
 			struct drm_connector *connector =
 				fb_helper->connector_info[i]->connector;
 
 			DRM_DEBUG_KMS("desired mode %s set on crtc %d (%d,%d)\n",
-				      mode->name, fb_crtc->mode_set.crtc->base.id, offset->x, offset->y);
+				      mode->name, crtc->base.id, offset->x, offset->y);
+
+			if (WARN_ON_ONCE(modeset->num_connectors == DRM_CLIENT_MAX_CLONED_CONNECTORS ||
+					 (dev->mode_config.num_crtc > 1 && modeset->num_connectors == 1)))
+				break;
 
 			modeset->mode = drm_mode_duplicate(dev, mode);
 			drm_connector_get(connector);
···
 			modeset->y = offset->y;
 		}
 	}
+
+	mutex_unlock(&client->modeset_mutex);
 out:
 	kfree(crtcs);
 	kfree(modes);
···
  */
 static void drm_setup_crtcs_fb(struct drm_fb_helper *fb_helper)
 {
+	struct drm_client_dev *client = &fb_helper->client;
 	struct fb_info *info = fb_helper->fbdev;
 	unsigned int rotation, sw_rotations = 0;
+	struct drm_mode_set *modeset;
 	int i;
 
-	for (i = 0; i < fb_helper->crtc_count; i++) {
-		struct drm_mode_set *modeset = &fb_helper->crtc_info[i].mode_set;
-
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(modeset, client) {
 		if (!modeset->num_connectors)
 			continue;
 
···
 		else
 			sw_rotations |= rotation;
 	}
+	mutex_unlock(&client->modeset_mutex);
 
 	mutex_lock(&fb_helper->dev->mode_config.mutex);
 	drm_fb_helper_for_each_connector(fb_helper, i) {
···
  * @funcs: fbdev helper functions
  * @preferred_bpp: Preferred bits per pixel for the device.
  *                 @dev->mode_config.preferred_depth is used if this is zero.
- * @max_conn_count: Maximum number of connectors.
- *                  @dev->mode_config.num_connector is used if this is zero.
+ * @max_conn_count: Maximum number of connectors (not used)
  *
  * This function sets up fbdev emulation and registers fbdev for access by
  * userspace. If all connectors are disconnected, setup is deferred to the next
···
 	if (!preferred_bpp)
 		preferred_bpp = 32;
 
-	if (!max_conn_count)
-		max_conn_count = dev->mode_config.num_connector;
-	if (!max_conn_count) {
-		DRM_DEV_ERROR(dev->dev, "fbdev: No connectors\n");
-		return -EINVAL;
-	}
-
 	drm_fb_helper_prepare(dev, fb_helper, funcs);
 
-	ret = drm_fb_helper_init(dev, fb_helper, max_conn_count);
+	ret = drm_fb_helper_init(dev, fb_helper, 0);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dev->dev, "fbdev: Failed to initialize (ret=%d)\n", ret);
 		return ret;
···
 
 	drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
 
-	ret = drm_fb_helper_init(dev, fb_helper, dev->mode_config.num_connector);
+	ret = drm_fb_helper_init(dev, fb_helper, 0);
 	if (ret)
 		goto err;
 

include/drm/drm_client.h

···
 #ifndef _DRM_CLIENT_H_
 #define _DRM_CLIENT_H_
 
+#include <linux/lockdep.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
+
+#include <drm/drm_crtc.h>
 
 struct drm_client_dev;
 struct drm_device;
···
 struct drm_gem_object;
 struct drm_minor;
 struct module;
+
+#define DRM_CLIENT_MAX_CLONED_CONNECTORS	8
 
 /**
  * struct drm_client_funcs - DRM client callbacks
···
 	 * @file: DRM file
 	 */
 	struct drm_file *file;
+
+	/**
+	 * @modeset_mutex: Protects @modesets.
+	 */
+	struct mutex modeset_mutex;
+
+	/**
+	 * @modesets: CRTC configurations
+	 */
+	struct drm_mode_set *modesets;
 };
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
···
 struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
+
+int drm_client_modeset_create(struct drm_client_dev *client);
+void drm_client_modeset_free(struct drm_client_dev *client);
+void drm_client_modeset_release(struct drm_client_dev *client);
+struct drm_mode_set *drm_client_find_modeset(struct drm_client_dev *client, struct drm_crtc *crtc);
+
+/**
+ * drm_client_for_each_modeset() - Iterate over client modesets
+ * @modeset: &drm_mode_set loop cursor
+ * @client: DRM client
+ */
+#define drm_client_for_each_modeset(modeset, client) \
+	for (({ lockdep_assert_held(&(client)->modeset_mutex); }), \
+	     modeset = (client)->modesets; modeset->crtc; modeset++)
 
 int drm_client_debugfs_init(struct drm_minor *minor);
 

include/drm/drm_fb_helper.h

···
 	int x, y;
 };
 
-struct drm_fb_helper_crtc {
-	struct drm_mode_set mode_set;
-};
-
 /**
  * struct drm_fb_helper_surface_size - describes fbdev size and scanout surface size
  * @fb_width: fbdev width
···
  * struct drm_fb_helper - main structure to emulate fbdev on top of KMS
  * @fb: Scanout framebuffer object
  * @dev: DRM device
- * @crtc_count: number of possible CRTCs
- * @crtc_info: per-CRTC helper state (mode, x/y offset, etc)
  * @connector_count: number of connected connectors
  * @connector_info_alloc_count: size of connector_info
  * @funcs: driver callbacks for fb helper
···
 
 	struct drm_framebuffer *fb;
 	struct drm_device *dev;
-	int crtc_count;
-	struct drm_fb_helper_crtc *crtc_info;
 	int connector_count;
 	int connector_info_alloc_count;
 	/**