2 * Copyright (c) 2006-2009 Red Hat Inc.
3 * Copyright (c) 2006-2008 Intel Corporation
4 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
6 * DRM framebuffer helper functions
8 * Permission to use, copy, modify, distribute, and sell this software and its
9 * documentation for any purpose is hereby granted without fee, provided that
10 * the above copyright notice appear in all copies and that both that copyright
11 * notice and this permission notice appear in supporting documentation, and
12 * that the name of the copyright holders not be used in advertising or
13 * publicity pertaining to distribution of the software without specific,
14 * written prior permission. The copyright holders make no representations
15 * about the suitability of this software for any purpose. It is provided "as
16 * is" without express or implied warranty.
18 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
19 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
20 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
21 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
22 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
23 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
27 * Dave Airlie <airlied@linux.ie>
28 * Jesse Barnes <jesse.barnes@intel.com>
30 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32 #include <linux/kernel.h>
33 #include <linux/sysrq.h>
34 #include <linux/slab.h>
36 #include <linux/module.h>
38 #include <drm/drm_crtc.h>
39 #include <drm/drm_fb_helper.h>
40 #include <drm/drm_crtc_helper.h>
42 static LIST_HEAD(kernel_fb_helper_list);
47 * The fb helper functions are useful to provide an fbdev on top of a drm kernel
48 * mode setting driver. They can be used mostly independantely from the crtc
49 * helper functions used by many drivers to implement the kernel mode setting
52 * Initialization is done as a three-step process with drm_fb_helper_init(),
53 * drm_fb_helper_single_add_all_connectors() and drm_fb_helper_initial_config().
54 * Drivers with fancier requirements than the default beheviour can override the
55 * second step with their own code. Teardown is done with drm_fb_helper_fini().
57 * At runtime drivers should restore the fbdev console by calling
58 * drm_fb_helper_restore_fbdev_mode() from their ->lastclose callback. They
59 * should also notify the fb helper code from updates to the output
60 * configuration by calling drm_fb_helper_hotplug_event(). For easier
61 * integration with the output polling code in drm_crtc_helper.c the modeset
62 * code proves a ->output_poll_changed callback.
64 * All other functions exported by the fb helper library can be used to
65 * implement the fbdev driver interface by the driver.
69 * drm_fb_helper_single_add_all_connectors() - add all connectors to fbdev
71 * @fb_helper: fbdev initialized with drm_fb_helper_init
73 * This functions adds all the available connectors for use with the given
74 * fb_helper. This is a separate step to allow drivers to freely assign
75 * connectors to the fbdev, e.g. if some are reserved for special purposes or
76 * not adequate to be used for the fbcon.
78 * Since this is part of the initial setup before the fbdev is published, no
79 * locking is required.
81 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
83 struct drm_device *dev = fb_helper->dev;
84 struct drm_connector *connector;
87 list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
88 struct drm_fb_helper_connector *fb_helper_connector;
90 fb_helper_connector = kzalloc(sizeof(struct drm_fb_helper_connector), GFP_KERNEL);
91 if (!fb_helper_connector)
94 fb_helper_connector->connector = connector;
95 fb_helper->connector_info[fb_helper->connector_count++] = fb_helper_connector;
99 for (i = 0; i < fb_helper->connector_count; i++) {
100 kfree(fb_helper->connector_info[i]);
101 fb_helper->connector_info[i] = NULL;
103 fb_helper->connector_count = 0;
106 EXPORT_SYMBOL(drm_fb_helper_single_add_all_connectors);
108 static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
110 struct drm_fb_helper_connector *fb_helper_conn;
113 for (i = 0; i < fb_helper->connector_count; i++) {
114 struct drm_cmdline_mode *mode;
115 struct drm_connector *connector;
118 fb_helper_conn = fb_helper->connector_info[i];
119 connector = fb_helper_conn->connector;
120 mode = &fb_helper_conn->cmdline_mode;
122 /* do something on return - turn off connector maybe */
123 if (fb_get_options(drm_get_connector_name(connector), &option))
126 if (drm_mode_parse_command_line_for_connector(option,
131 switch (mode->force) {
135 case DRM_FORCE_ON_DIGITAL:
144 DRM_INFO("forcing %s connector %s\n",
145 drm_get_connector_name(connector), s);
146 connector->force = mode->force;
149 DRM_DEBUG_KMS("cmdline mode for connector %s %dx%d@%dHz%s%s%s\n",
150 drm_get_connector_name(connector),
151 mode->xres, mode->yres,
152 mode->refresh_specified ? mode->refresh : 60,
153 mode->rb ? " reduced blanking" : "",
154 mode->margins ? " with margins" : "",
155 mode->interlace ? " interlaced" : "");
162 static void drm_fb_helper_save_lut_atomic(struct drm_crtc *crtc, struct drm_fb_helper *helper)
164 uint16_t *r_base, *g_base, *b_base;
167 if (helper->funcs->gamma_get == NULL)
170 r_base = crtc->gamma_store;
171 g_base = r_base + crtc->gamma_size;
172 b_base = g_base + crtc->gamma_size;
174 for (i = 0; i < crtc->gamma_size; i++)
175 helper->funcs->gamma_get(crtc, &r_base[i], &g_base[i], &b_base[i], i);
178 static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
180 uint16_t *r_base, *g_base, *b_base;
182 if (crtc->funcs->gamma_set == NULL)
185 r_base = crtc->gamma_store;
186 g_base = r_base + crtc->gamma_size;
187 b_base = g_base + crtc->gamma_size;
189 crtc->funcs->gamma_set(crtc, r_base, g_base, b_base, 0, crtc->gamma_size);
193 * drm_fb_helper_debug_enter - implementation for ->fb_debug_enter
194 * @info: fbdev registered by the helper
196 int drm_fb_helper_debug_enter(struct fb_info *info)
198 struct drm_fb_helper *helper = info->par;
199 struct drm_crtc_helper_funcs *funcs;
202 if (list_empty(&kernel_fb_helper_list))
205 list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
206 for (i = 0; i < helper->crtc_count; i++) {
207 struct drm_mode_set *mode_set =
208 &helper->crtc_info[i].mode_set;
210 if (!mode_set->crtc->enabled)
213 funcs = mode_set->crtc->helper_private;
214 drm_fb_helper_save_lut_atomic(mode_set->crtc, helper);
215 funcs->mode_set_base_atomic(mode_set->crtc,
219 ENTER_ATOMIC_MODE_SET);
225 EXPORT_SYMBOL(drm_fb_helper_debug_enter);
227 /* Find the real fb for a given fb helper CRTC */
228 static struct drm_framebuffer *drm_mode_config_fb(struct drm_crtc *crtc)
230 struct drm_device *dev = crtc->dev;
233 list_for_each_entry(c, &dev->mode_config.crtc_list, head) {
234 if (crtc->base.id == c->base.id)
235 return c->primary->fb;
242 * drm_fb_helper_debug_leave - implementation for ->fb_debug_leave
243 * @info: fbdev registered by the helper
245 int drm_fb_helper_debug_leave(struct fb_info *info)
247 struct drm_fb_helper *helper = info->par;
248 struct drm_crtc *crtc;
249 struct drm_crtc_helper_funcs *funcs;
250 struct drm_framebuffer *fb;
253 for (i = 0; i < helper->crtc_count; i++) {
254 struct drm_mode_set *mode_set = &helper->crtc_info[i].mode_set;
255 crtc = mode_set->crtc;
256 funcs = crtc->helper_private;
257 fb = drm_mode_config_fb(crtc);
263 DRM_ERROR("no fb to restore??\n");
267 drm_fb_helper_restore_lut_atomic(mode_set->crtc);
268 funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
269 crtc->y, LEAVE_ATOMIC_MODE_SET);
274 EXPORT_SYMBOL(drm_fb_helper_debug_leave);
277 * drm_fb_helper_restore_fbdev_mode - restore fbdev configuration
278 * @fb_helper: fbcon to restore
280 * This should be called from driver's drm ->lastclose callback
281 * when implementing an fbcon on top of kms using this helper. This ensures that
282 * the user isn't greeted with a black screen when e.g. X dies.
284 bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
286 struct drm_device *dev = fb_helper->dev;
287 struct drm_plane *plane;
291 drm_warn_on_modeset_not_all_locked(dev);
293 list_for_each_entry(plane, &dev->mode_config.plane_list, head)
294 if (plane->type != DRM_PLANE_TYPE_PRIMARY)
295 drm_plane_force_disable(plane);
297 for (i = 0; i < fb_helper->crtc_count; i++) {
298 struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
299 struct drm_crtc *crtc = mode_set->crtc;
302 if (crtc->funcs->cursor_set) {
303 ret = crtc->funcs->cursor_set(crtc, NULL, 0, 0, 0);
308 ret = drm_mode_set_config_internal(mode_set);
314 EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode);
317 * restore fbcon display for all kms driver's using this helper, used for sysrq
318 * and panic handling.
320 static bool drm_fb_helper_force_kernel_mode(void)
322 bool ret, error = false;
323 struct drm_fb_helper *helper;
325 if (list_empty(&kernel_fb_helper_list))
328 list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
329 if (helper->dev->switch_power_state == DRM_SWITCH_POWER_OFF)
332 ret = drm_fb_helper_restore_fbdev_mode(helper);
339 static int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
343 * It's a waste of time and effort to switch back to text console
344 * if the kernel should reboot before panic messages can be seen.
346 if (panic_timeout < 0)
349 pr_err("panic occurred, switching back to text console\n");
350 return drm_fb_helper_force_kernel_mode();
353 static struct notifier_block paniced = {
354 .notifier_call = drm_fb_helper_panic,
357 static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper)
359 struct drm_device *dev = fb_helper->dev;
360 struct drm_crtc *crtc;
361 int bound = 0, crtcs_bound = 0;
363 /* Sometimes user space wants everything disabled, so don't steal the
364 * display if there's a master. */
365 if (dev->primary->master)
368 list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
369 if (crtc->primary->fb)
371 if (crtc->primary->fb == fb_helper->fb)
375 if (bound < crtcs_bound)
381 #ifdef CONFIG_MAGIC_SYSRQ
382 static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
385 ret = drm_fb_helper_force_kernel_mode();
387 DRM_ERROR("Failed to restore crtc configuration\n");
389 static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
391 static void drm_fb_helper_sysrq(int dummy1)
393 schedule_work(&drm_fb_helper_restore_work);
396 static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
397 .handler = drm_fb_helper_sysrq,
398 .help_msg = "force-fb(V)",
399 .action_msg = "Restore framebuffer console",
402 static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
405 static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
407 struct drm_fb_helper *fb_helper = info->par;
408 struct drm_device *dev = fb_helper->dev;
409 struct drm_crtc *crtc;
410 struct drm_connector *connector;
414 * fbdev->blank can be called from irq context in case of a panic.
415 * Since we already have our own special panic handler which will
416 * restore the fbdev console mode completely, just bail out early.
418 if (oops_in_progress)
422 * For each CRTC in this fb, turn the connectors on/off.
424 drm_modeset_lock_all(dev);
425 if (!drm_fb_helper_is_bound(fb_helper)) {
426 drm_modeset_unlock_all(dev);
430 for (i = 0; i < fb_helper->crtc_count; i++) {
431 crtc = fb_helper->crtc_info[i].mode_set.crtc;
436 /* Walk the connectors & encoders on this fb turning them on/off */
437 for (j = 0; j < fb_helper->connector_count; j++) {
438 connector = fb_helper->connector_info[j]->connector;
439 connector->funcs->dpms(connector, dpms_mode);
440 drm_object_property_set_value(&connector->base,
441 dev->mode_config.dpms_property, dpms_mode);
444 drm_modeset_unlock_all(dev);
448 * drm_fb_helper_blank - implementation for ->fb_blank
449 * @blank: desired blanking state
450 * @info: fbdev registered by the helper
452 int drm_fb_helper_blank(int blank, struct fb_info *info)
455 /* Display: On; HSync: On, VSync: On */
456 case FB_BLANK_UNBLANK:
457 drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
459 /* Display: Off; HSync: On, VSync: On */
460 case FB_BLANK_NORMAL:
461 drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
463 /* Display: Off; HSync: Off, VSync: On */
464 case FB_BLANK_HSYNC_SUSPEND:
465 drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
467 /* Display: Off; HSync: On, VSync: Off */
468 case FB_BLANK_VSYNC_SUSPEND:
469 drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
471 /* Display: Off; HSync: Off, VSync: Off */
472 case FB_BLANK_POWERDOWN:
473 drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
478 EXPORT_SYMBOL(drm_fb_helper_blank);
480 static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
484 for (i = 0; i < helper->connector_count; i++)
485 kfree(helper->connector_info[i]);
486 kfree(helper->connector_info);
487 for (i = 0; i < helper->crtc_count; i++) {
488 kfree(helper->crtc_info[i].mode_set.connectors);
489 if (helper->crtc_info[i].mode_set.mode)
490 drm_mode_destroy(helper->dev, helper->crtc_info[i].mode_set.mode);
492 kfree(helper->crtc_info);
496 * drm_fb_helper_init - initialize a drm_fb_helper structure
498 * @fb_helper: driver-allocated fbdev helper structure to initialize
499 * @crtc_count: maximum number of crtcs to support in this fbdev emulation
500 * @max_conn_count: max connector count
502 * This allocates the structures for the fbdev helper with the given limits.
503 * Note that this won't yet touch the hardware (through the driver interfaces)
504 * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
505 * to allow driver writes more control over the exact init sequence.
507 * Drivers must set fb_helper->funcs before calling
508 * drm_fb_helper_initial_config().
511 * Zero if everything went ok, nonzero otherwise.
513 int drm_fb_helper_init(struct drm_device *dev,
514 struct drm_fb_helper *fb_helper,
515 int crtc_count, int max_conn_count)
517 struct drm_crtc *crtc;
523 fb_helper->dev = dev;
525 INIT_LIST_HEAD(&fb_helper->kernel_fb_list);
527 fb_helper->crtc_info = kcalloc(crtc_count, sizeof(struct drm_fb_helper_crtc), GFP_KERNEL);
528 if (!fb_helper->crtc_info)
531 fb_helper->crtc_count = crtc_count;
532 fb_helper->connector_info = kcalloc(dev->mode_config.num_connector, sizeof(struct drm_fb_helper_connector *), GFP_KERNEL);
533 if (!fb_helper->connector_info) {
534 kfree(fb_helper->crtc_info);
537 fb_helper->connector_count = 0;
539 for (i = 0; i < crtc_count; i++) {
540 fb_helper->crtc_info[i].mode_set.connectors =
541 kcalloc(max_conn_count,
542 sizeof(struct drm_connector *),
545 if (!fb_helper->crtc_info[i].mode_set.connectors)
547 fb_helper->crtc_info[i].mode_set.num_connectors = 0;
551 list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
552 fb_helper->crtc_info[i].mode_set.crtc = crtc;
558 drm_fb_helper_crtc_free(fb_helper);
561 EXPORT_SYMBOL(drm_fb_helper_init);
563 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
565 if (!list_empty(&fb_helper->kernel_fb_list)) {
566 list_del(&fb_helper->kernel_fb_list);
567 if (list_empty(&kernel_fb_helper_list)) {
568 pr_info("drm: unregistered panic notifier\n");
569 atomic_notifier_chain_unregister(&panic_notifier_list,
571 unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
575 drm_fb_helper_crtc_free(fb_helper);
578 EXPORT_SYMBOL(drm_fb_helper_fini);
580 static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
581 u16 blue, u16 regno, struct fb_info *info)
583 struct drm_fb_helper *fb_helper = info->par;
584 struct drm_framebuffer *fb = fb_helper->fb;
587 if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
590 /* place color in psuedopalette */
593 palette = (u32 *)info->pseudo_palette;
594 red >>= (16 - info->var.red.length);
595 green >>= (16 - info->var.green.length);
596 blue >>= (16 - info->var.blue.length);
597 value = (red << info->var.red.offset) |
598 (green << info->var.green.offset) |
599 (blue << info->var.blue.offset);
600 if (info->var.transp.length > 0) {
601 u32 mask = (1 << info->var.transp.length) - 1;
602 mask <<= info->var.transp.offset;
605 palette[regno] = value;
610 * The driver really shouldn't advertise pseudo/directcolor
611 * visuals if it can't deal with the palette.
613 if (WARN_ON(!fb_helper->funcs->gamma_set ||
614 !fb_helper->funcs->gamma_get))
619 if (fb->bits_per_pixel == 16) {
622 if (fb->depth == 16 && regno > 63)
624 if (fb->depth == 15 && regno > 31)
627 if (fb->depth == 16) {
631 for (i = 0; i < 8; i++)
632 fb_helper->funcs->gamma_set(crtc, red,
633 green, blue, pindex + i);
636 fb_helper->funcs->gamma_get(crtc, &r,
640 for (i = 0; i < 4; i++)
641 fb_helper->funcs->gamma_set(crtc, r,
648 fb_helper->funcs->gamma_set(crtc, red, green, blue, pindex);
653 * drm_fb_helper_setcmap - implementation for ->fb_setcmap
655 * @info: fbdev registered by the helper
657 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
659 struct drm_fb_helper *fb_helper = info->par;
660 struct drm_device *dev = fb_helper->dev;
661 struct drm_crtc_helper_funcs *crtc_funcs;
662 u16 *red, *green, *blue, *transp;
663 struct drm_crtc *crtc;
667 drm_modeset_lock_all(dev);
668 if (!drm_fb_helper_is_bound(fb_helper)) {
669 drm_modeset_unlock_all(dev);
673 for (i = 0; i < fb_helper->crtc_count; i++) {
674 crtc = fb_helper->crtc_info[i].mode_set.crtc;
675 crtc_funcs = crtc->helper_private;
680 transp = cmap->transp;
683 for (j = 0; j < cmap->len; j++) {
684 u16 hred, hgreen, hblue, htransp = 0xffff;
693 rc = setcolreg(crtc, hred, hgreen, hblue, start++, info);
697 if (crtc_funcs->load_lut)
698 crtc_funcs->load_lut(crtc);
701 drm_modeset_unlock_all(dev);
704 EXPORT_SYMBOL(drm_fb_helper_setcmap);
707 * drm_fb_helper_check_var - implementation for ->fb_check_var
708 * @var: screeninfo to check
709 * @info: fbdev registered by the helper
711 int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
712 struct fb_info *info)
714 struct drm_fb_helper *fb_helper = info->par;
715 struct drm_framebuffer *fb = fb_helper->fb;
718 if (var->pixclock != 0 || in_dbg_master())
721 /* Need to resize the fb object !!! */
722 if (var->bits_per_pixel > fb->bits_per_pixel ||
723 var->xres > fb->width || var->yres > fb->height ||
724 var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
725 DRM_DEBUG("fb userspace requested width/height/bpp is greater than current fb "
726 "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
727 var->xres, var->yres, var->bits_per_pixel,
728 var->xres_virtual, var->yres_virtual,
729 fb->width, fb->height, fb->bits_per_pixel);
733 switch (var->bits_per_pixel) {
735 depth = (var->green.length == 6) ? 16 : 15;
738 depth = (var->transp.length > 0) ? 32 : 24;
741 depth = var->bits_per_pixel;
748 var->green.offset = 0;
749 var->blue.offset = 0;
751 var->green.length = 8;
752 var->blue.length = 8;
753 var->transp.length = 0;
754 var->transp.offset = 0;
757 var->red.offset = 10;
758 var->green.offset = 5;
759 var->blue.offset = 0;
761 var->green.length = 5;
762 var->blue.length = 5;
763 var->transp.length = 1;
764 var->transp.offset = 15;
767 var->red.offset = 11;
768 var->green.offset = 5;
769 var->blue.offset = 0;
771 var->green.length = 6;
772 var->blue.length = 5;
773 var->transp.length = 0;
774 var->transp.offset = 0;
777 var->red.offset = 16;
778 var->green.offset = 8;
779 var->blue.offset = 0;
781 var->green.length = 8;
782 var->blue.length = 8;
783 var->transp.length = 0;
784 var->transp.offset = 0;
787 var->red.offset = 16;
788 var->green.offset = 8;
789 var->blue.offset = 0;
791 var->green.length = 8;
792 var->blue.length = 8;
793 var->transp.length = 8;
794 var->transp.offset = 24;
801 EXPORT_SYMBOL(drm_fb_helper_check_var);
804 * drm_fb_helper_set_par - implementation for ->fb_set_par
805 * @info: fbdev registered by the helper
807 * This will let fbcon do the mode init and is called at initialization time by
808 * the fbdev core when registering the driver, and later on through the hotplug
811 int drm_fb_helper_set_par(struct fb_info *info)
813 struct drm_fb_helper *fb_helper = info->par;
814 struct drm_device *dev = fb_helper->dev;
815 struct fb_var_screeninfo *var = &info->var;
817 if (var->pixclock != 0) {
818 DRM_ERROR("PIXEL CLOCK SET\n");
822 drm_modeset_lock_all(dev);
823 drm_fb_helper_restore_fbdev_mode(fb_helper);
824 drm_modeset_unlock_all(dev);
826 if (fb_helper->delayed_hotplug) {
827 fb_helper->delayed_hotplug = false;
828 drm_fb_helper_hotplug_event(fb_helper);
832 EXPORT_SYMBOL(drm_fb_helper_set_par);
835 * drm_fb_helper_pan_display - implementation for ->fb_pan_display
836 * @var: updated screen information
837 * @info: fbdev registered by the helper
839 int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
840 struct fb_info *info)
842 struct drm_fb_helper *fb_helper = info->par;
843 struct drm_device *dev = fb_helper->dev;
844 struct drm_mode_set *modeset;
848 drm_modeset_lock_all(dev);
849 if (!drm_fb_helper_is_bound(fb_helper)) {
850 drm_modeset_unlock_all(dev);
854 for (i = 0; i < fb_helper->crtc_count; i++) {
855 modeset = &fb_helper->crtc_info[i].mode_set;
857 modeset->x = var->xoffset;
858 modeset->y = var->yoffset;
860 if (modeset->num_connectors) {
861 ret = drm_mode_set_config_internal(modeset);
863 info->var.xoffset = var->xoffset;
864 info->var.yoffset = var->yoffset;
868 drm_modeset_unlock_all(dev);
871 EXPORT_SYMBOL(drm_fb_helper_pan_display);
874 * Allocates the backing storage and sets up the fbdev info structure through
875 * the ->fb_probe callback and then registers the fbdev and sets up the panic
878 static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
884 struct fb_info *info;
885 struct drm_fb_helper_surface_size sizes;
888 memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
889 sizes.surface_depth = 24;
890 sizes.surface_bpp = 32;
891 sizes.fb_width = (unsigned)-1;
892 sizes.fb_height = (unsigned)-1;
894 /* if driver picks 8 or 16 by default use that
895 for both depth/bpp */
896 if (preferred_bpp != sizes.surface_bpp)
897 sizes.surface_depth = sizes.surface_bpp = preferred_bpp;
899 /* first up get a count of crtcs now in use and new min/maxes width/heights */
900 for (i = 0; i < fb_helper->connector_count; i++) {
901 struct drm_fb_helper_connector *fb_helper_conn = fb_helper->connector_info[i];
902 struct drm_cmdline_mode *cmdline_mode;
904 cmdline_mode = &fb_helper_conn->cmdline_mode;
906 if (cmdline_mode->bpp_specified) {
907 switch (cmdline_mode->bpp) {
909 sizes.surface_depth = sizes.surface_bpp = 8;
912 sizes.surface_depth = 15;
913 sizes.surface_bpp = 16;
916 sizes.surface_depth = sizes.surface_bpp = 16;
919 sizes.surface_depth = sizes.surface_bpp = 24;
922 sizes.surface_depth = 24;
923 sizes.surface_bpp = 32;
931 for (i = 0; i < fb_helper->crtc_count; i++) {
932 struct drm_display_mode *desired_mode;
933 desired_mode = fb_helper->crtc_info[i].desired_mode;
937 gamma_size = fb_helper->crtc_info[i].mode_set.crtc->gamma_size;
938 if (desired_mode->hdisplay < sizes.fb_width)
939 sizes.fb_width = desired_mode->hdisplay;
940 if (desired_mode->vdisplay < sizes.fb_height)
941 sizes.fb_height = desired_mode->vdisplay;
942 if (desired_mode->hdisplay > sizes.surface_width)
943 sizes.surface_width = desired_mode->hdisplay;
944 if (desired_mode->vdisplay > sizes.surface_height)
945 sizes.surface_height = desired_mode->vdisplay;
950 if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
951 /* hmm everyone went away - assume VGA cable just fell out
952 and will come back later. */
953 DRM_INFO("Cannot find any crtc or sizes - going 1024x768\n");
954 sizes.fb_width = sizes.surface_width = 1024;
955 sizes.fb_height = sizes.surface_height = 768;
958 /* push down into drivers */
959 ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
963 info = fb_helper->fbdev;
966 * Set the fb pointer - usually drm_setup_crtcs does this for hotplug
967 * events, but at init time drm_setup_crtcs needs to be called before
968 * the fb is allocated (since we need to figure out the desired size of
969 * the fb before we can allocate it ...). Hence we need to fix things up
972 for (i = 0; i < fb_helper->crtc_count; i++)
973 if (fb_helper->crtc_info[i].mode_set.num_connectors)
974 fb_helper->crtc_info[i].mode_set.fb = fb_helper->fb;
977 info->var.pixclock = 0;
978 if (register_framebuffer(info) < 0)
981 dev_info(fb_helper->dev->dev, "fb%d: %s frame buffer device\n",
982 info->node, info->fix.id);
984 /* Switch back to kernel console on panic */
985 /* multi card linked list maybe */
986 if (list_empty(&kernel_fb_helper_list)) {
987 dev_info(fb_helper->dev->dev, "registered panic notifier\n");
988 atomic_notifier_chain_register(&panic_notifier_list,
990 register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
993 list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
999 * drm_fb_helper_fill_fix - initializes fixed fbdev information
1000 * @info: fbdev registered by the helper
1001 * @pitch: desired pitch
1002 * @depth: desired depth
1004 * Helper to fill in the fixed fbdev information useful for a non-accelerated
1005 * fbdev emulations. Drivers which support acceleration methods which impose
1006 * additional constraints need to set up their own limits.
1008 * Drivers should call this (or their equivalent setup code) from their
1009 * ->fb_probe callback.
1011 void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
1014 info->fix.type = FB_TYPE_PACKED_PIXELS;
1015 info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
1016 FB_VISUAL_TRUECOLOR;
1017 info->fix.mmio_start = 0;
1018 info->fix.mmio_len = 0;
1019 info->fix.type_aux = 0;
1020 info->fix.xpanstep = 1; /* doing it in hw */
1021 info->fix.ypanstep = 1; /* doing it in hw */
1022 info->fix.ywrapstep = 0;
1023 info->fix.accel = FB_ACCEL_NONE;
1024 info->fix.type_aux = 0;
1026 info->fix.line_length = pitch;
1029 EXPORT_SYMBOL(drm_fb_helper_fill_fix);
1032 * drm_fb_helper_fill_var - initalizes variable fbdev information
1033 * @info: fbdev instance to set up
1034 * @fb_helper: fb helper instance to use as template
1035 * @fb_width: desired fb width
1036 * @fb_height: desired fb height
1038 * Sets up the variable fbdev metainformation from the given fb helper instance
1039 * and the drm framebuffer allocated in fb_helper->fb.
1041 * Drivers should call this (or their equivalent setup code) from their
1042 * ->fb_probe callback after having allocated the fbdev backing
1043 * storage framebuffer.
1045 void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
1046 uint32_t fb_width, uint32_t fb_height)
1048 struct drm_framebuffer *fb = fb_helper->fb;
1049 info->pseudo_palette = fb_helper->pseudo_palette;
1050 info->var.xres_virtual = fb->width;
1051 info->var.yres_virtual = fb->height;
1052 info->var.bits_per_pixel = fb->bits_per_pixel;
1053 info->var.accel_flags = FB_ACCELF_TEXT;
1054 info->var.xoffset = 0;
1055 info->var.yoffset = 0;
1056 info->var.activate = FB_ACTIVATE_NOW;
1057 info->var.height = -1;
1058 info->var.width = -1;
1060 switch (fb->depth) {
1062 info->var.red.offset = 0;
1063 info->var.green.offset = 0;
1064 info->var.blue.offset = 0;
1065 info->var.red.length = 8; /* 8bit DAC */
1066 info->var.green.length = 8;
1067 info->var.blue.length = 8;
1068 info->var.transp.offset = 0;
1069 info->var.transp.length = 0;
1072 info->var.red.offset = 10;
1073 info->var.green.offset = 5;
1074 info->var.blue.offset = 0;
1075 info->var.red.length = 5;
1076 info->var.green.length = 5;
1077 info->var.blue.length = 5;
1078 info->var.transp.offset = 15;
1079 info->var.transp.length = 1;
1082 info->var.red.offset = 11;
1083 info->var.green.offset = 5;
1084 info->var.blue.offset = 0;
1085 info->var.red.length = 5;
1086 info->var.green.length = 6;
1087 info->var.blue.length = 5;
1088 info->var.transp.offset = 0;
1091 info->var.red.offset = 16;
1092 info->var.green.offset = 8;
1093 info->var.blue.offset = 0;
1094 info->var.red.length = 8;
1095 info->var.green.length = 8;
1096 info->var.blue.length = 8;
1097 info->var.transp.offset = 0;
1098 info->var.transp.length = 0;
1101 info->var.red.offset = 16;
1102 info->var.green.offset = 8;
1103 info->var.blue.offset = 0;
1104 info->var.red.length = 8;
1105 info->var.green.length = 8;
1106 info->var.blue.length = 8;
1107 info->var.transp.offset = 24;
1108 info->var.transp.length = 8;
1114 info->var.xres = fb_width;
1115 info->var.yres = fb_height;
1117 EXPORT_SYMBOL(drm_fb_helper_fill_var);
1119 static int drm_fb_helper_probe_connector_modes(struct drm_fb_helper *fb_helper,
1123 struct drm_connector *connector;
1127 for (i = 0; i < fb_helper->connector_count; i++) {
1128 connector = fb_helper->connector_info[i]->connector;
1129 count += connector->funcs->fill_modes(connector, maxX, maxY);
1135 struct drm_display_mode *drm_has_preferred_mode(struct drm_fb_helper_connector *fb_connector, int width, int height)
1137 struct drm_display_mode *mode;
1139 list_for_each_entry(mode, &fb_connector->connector->modes, head) {
1140 if (mode->hdisplay > width ||
1141 mode->vdisplay > height)
1143 if (mode->type & DRM_MODE_TYPE_PREFERRED)
1148 EXPORT_SYMBOL(drm_has_preferred_mode);
1150 static bool drm_has_cmdline_mode(struct drm_fb_helper_connector *fb_connector)
1152 struct drm_cmdline_mode *cmdline_mode;
1153 cmdline_mode = &fb_connector->cmdline_mode;
1154 return cmdline_mode->specified;
1157 struct drm_display_mode *drm_pick_cmdline_mode(struct drm_fb_helper_connector *fb_helper_conn,
1158 int width, int height)
1160 struct drm_cmdline_mode *cmdline_mode;
1161 struct drm_display_mode *mode = NULL;
1162 bool prefer_non_interlace;
1164 cmdline_mode = &fb_helper_conn->cmdline_mode;
1165 if (cmdline_mode->specified == false)
1168 /* attempt to find a matching mode in the list of modes
1169 * we have gotten so far, if not add a CVT mode that conforms
1171 if (cmdline_mode->rb || cmdline_mode->margins)
1174 prefer_non_interlace = !cmdline_mode->interlace;
1176 list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
1177 /* check width/height */
1178 if (mode->hdisplay != cmdline_mode->xres ||
1179 mode->vdisplay != cmdline_mode->yres)
1182 if (cmdline_mode->refresh_specified) {
1183 if (mode->vrefresh != cmdline_mode->refresh)
1187 if (cmdline_mode->interlace) {
1188 if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
1190 } else if (prefer_non_interlace) {
1191 if (mode->flags & DRM_MODE_FLAG_INTERLACE)
1197 if (prefer_non_interlace) {
1198 prefer_non_interlace = false;
1203 mode = drm_mode_create_from_cmdline_mode(fb_helper_conn->connector->dev,
1205 list_add(&mode->head, &fb_helper_conn->connector->modes);
1208 EXPORT_SYMBOL(drm_pick_cmdline_mode);
1210 static bool drm_connector_enabled(struct drm_connector *connector, bool strict)
1215 enable = connector->status == connector_status_connected;
1217 enable = connector->status != connector_status_disconnected;
1222 static void drm_enable_connectors(struct drm_fb_helper *fb_helper,
1225 bool any_enabled = false;
1226 struct drm_connector *connector;
1229 for (i = 0; i < fb_helper->connector_count; i++) {
1230 connector = fb_helper->connector_info[i]->connector;
1231 enabled[i] = drm_connector_enabled(connector, true);
1232 DRM_DEBUG_KMS("connector %d enabled? %s\n", connector->base.id,
1233 enabled[i] ? "yes" : "no");
1234 any_enabled |= enabled[i];
1240 for (i = 0; i < fb_helper->connector_count; i++) {
1241 connector = fb_helper->connector_info[i]->connector;
1242 enabled[i] = drm_connector_enabled(connector, false);
1246 static bool drm_target_cloned(struct drm_fb_helper *fb_helper,
1247 struct drm_display_mode **modes,
1248 bool *enabled, int width, int height)
1251 bool can_clone = false;
1252 struct drm_fb_helper_connector *fb_helper_conn;
1253 struct drm_display_mode *dmt_mode, *mode;
1255 /* only contemplate cloning in the single crtc case */
1256 if (fb_helper->crtc_count > 1)
1260 for (i = 0; i < fb_helper->connector_count; i++) {
1265 /* only contemplate cloning if more than one connector is enabled */
1269 /* check the command line or if nothing common pick 1024x768 */
1271 for (i = 0; i < fb_helper->connector_count; i++) {
1274 fb_helper_conn = fb_helper->connector_info[i];
1275 modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
1280 for (j = 0; j < i; j++) {
1283 if (!drm_mode_equal(modes[j], modes[i]))
1289 DRM_DEBUG_KMS("can clone using command line\n");
1293 /* try and find a 1024x768 mode on each connector */
1295 dmt_mode = drm_mode_find_dmt(fb_helper->dev, 1024, 768, 60, false);
1297 for (i = 0; i < fb_helper->connector_count; i++) {
1302 fb_helper_conn = fb_helper->connector_info[i];
1303 list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
1304 if (drm_mode_equal(mode, dmt_mode))
1312 DRM_DEBUG_KMS("can clone using 1024x768\n");
1315 DRM_INFO("kms: can't enable cloning when we probably wanted to.\n");
1319 static bool drm_target_preferred(struct drm_fb_helper *fb_helper,
1320 struct drm_display_mode **modes,
1321 bool *enabled, int width, int height)
1323 struct drm_fb_helper_connector *fb_helper_conn;
1326 for (i = 0; i < fb_helper->connector_count; i++) {
1327 fb_helper_conn = fb_helper->connector_info[i];
1329 if (enabled[i] == false)
1332 DRM_DEBUG_KMS("looking for cmdline mode on connector %d\n",
1333 fb_helper_conn->connector->base.id);
1335 /* got for command line mode first */
1336 modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
1338 DRM_DEBUG_KMS("looking for preferred mode on connector %d\n",
1339 fb_helper_conn->connector->base.id);
1340 modes[i] = drm_has_preferred_mode(fb_helper_conn, width, height);
1342 /* No preferred modes, pick one off the list */
1343 if (!modes[i] && !list_empty(&fb_helper_conn->connector->modes)) {
1344 list_for_each_entry(modes[i], &fb_helper_conn->connector->modes, head)
1347 DRM_DEBUG_KMS("found mode %s\n", modes[i] ? modes[i]->name :
1353 static int drm_pick_crtcs(struct drm_fb_helper *fb_helper,
1354 struct drm_fb_helper_crtc **best_crtcs,
1355 struct drm_display_mode **modes,
1356 int n, int width, int height)
1359 struct drm_device *dev = fb_helper->dev;
1360 struct drm_connector *connector;
1361 struct drm_connector_helper_funcs *connector_funcs;
1362 struct drm_encoder *encoder;
1363 int my_score, best_score, score;
1364 struct drm_fb_helper_crtc **crtcs, *crtc;
1365 struct drm_fb_helper_connector *fb_helper_conn;
1367 if (n == fb_helper->connector_count)
1370 fb_helper_conn = fb_helper->connector_info[n];
1371 connector = fb_helper_conn->connector;
1373 best_crtcs[n] = NULL;
1374 best_score = drm_pick_crtcs(fb_helper, best_crtcs, modes, n+1, width, height);
1375 if (modes[n] == NULL)
1378 crtcs = kzalloc(dev->mode_config.num_connector *
1379 sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
1384 if (connector->status == connector_status_connected)
1386 if (drm_has_cmdline_mode(fb_helper_conn))
1388 if (drm_has_preferred_mode(fb_helper_conn, width, height))
1391 connector_funcs = connector->helper_private;
1392 encoder = connector_funcs->best_encoder(connector);
1396 /* select a crtc for this connector and then attempt to configure
1397 remaining connectors */
1398 for (c = 0; c < fb_helper->crtc_count; c++) {
1399 crtc = &fb_helper->crtc_info[c];
1401 if ((encoder->possible_crtcs & (1 << c)) == 0)
1404 for (o = 0; o < n; o++)
1405 if (best_crtcs[o] == crtc)
1409 /* ignore cloning unless only a single crtc */
1410 if (fb_helper->crtc_count > 1)
1413 if (!drm_mode_equal(modes[o], modes[n]))
1418 memcpy(crtcs, best_crtcs, n * sizeof(struct drm_fb_helper_crtc *));
1419 score = my_score + drm_pick_crtcs(fb_helper, crtcs, modes, n + 1,
1421 if (score > best_score) {
1423 memcpy(best_crtcs, crtcs,
1424 dev->mode_config.num_connector *
1425 sizeof(struct drm_fb_helper_crtc *));
1433 static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
1435 struct drm_device *dev = fb_helper->dev;
1436 struct drm_fb_helper_crtc **crtcs;
1437 struct drm_display_mode **modes;
1438 struct drm_mode_set *modeset;
1443 DRM_DEBUG_KMS("\n");
1445 width = dev->mode_config.max_width;
1446 height = dev->mode_config.max_height;
1448 crtcs = kcalloc(dev->mode_config.num_connector,
1449 sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
1450 modes = kcalloc(dev->mode_config.num_connector,
1451 sizeof(struct drm_display_mode *), GFP_KERNEL);
1452 enabled = kcalloc(dev->mode_config.num_connector,
1453 sizeof(bool), GFP_KERNEL);
1454 if (!crtcs || !modes || !enabled) {
1455 DRM_ERROR("Memory allocation failed\n");
1460 drm_enable_connectors(fb_helper, enabled);
1462 if (!(fb_helper->funcs->initial_config &&
1463 fb_helper->funcs->initial_config(fb_helper, crtcs, modes,
1464 enabled, width, height))) {
1465 memset(modes, 0, dev->mode_config.num_connector*sizeof(modes[0]));
1466 memset(crtcs, 0, dev->mode_config.num_connector*sizeof(crtcs[0]));
1468 if (!drm_target_cloned(fb_helper,
1469 modes, enabled, width, height) &&
1470 !drm_target_preferred(fb_helper,
1471 modes, enabled, width, height))
1472 DRM_ERROR("Unable to find initial modes\n");
1474 DRM_DEBUG_KMS("picking CRTCs for %dx%d config\n",
1477 drm_pick_crtcs(fb_helper, crtcs, modes, 0, width, height);
1480 /* need to set the modesets up here for use later */
1481 /* fill out the connector<->crtc mappings into the modesets */
1482 for (i = 0; i < fb_helper->crtc_count; i++) {
1483 modeset = &fb_helper->crtc_info[i].mode_set;
1484 modeset->num_connectors = 0;
1488 for (i = 0; i < fb_helper->connector_count; i++) {
1489 struct drm_display_mode *mode = modes[i];
1490 struct drm_fb_helper_crtc *fb_crtc = crtcs[i];
1491 modeset = &fb_crtc->mode_set;
1493 if (mode && fb_crtc) {
1494 DRM_DEBUG_KMS("desired mode %s set on crtc %d\n",
1495 mode->name, fb_crtc->mode_set.crtc->base.id);
1496 fb_crtc->desired_mode = mode;
1498 drm_mode_destroy(dev, modeset->mode);
1499 modeset->mode = drm_mode_duplicate(dev,
1500 fb_crtc->desired_mode);
1501 modeset->connectors[modeset->num_connectors++] = fb_helper->connector_info[i]->connector;
1502 modeset->fb = fb_helper->fb;
1506 /* Clear out any old modes if there are no more connected outputs. */
1507 for (i = 0; i < fb_helper->crtc_count; i++) {
1508 modeset = &fb_helper->crtc_info[i].mode_set;
1509 if (modeset->num_connectors == 0) {
1510 BUG_ON(modeset->fb);
1511 BUG_ON(modeset->num_connectors);
1513 drm_mode_destroy(dev, modeset->mode);
1514 modeset->mode = NULL;
1524 * drm_fb_helper_initial_config - setup a sane initial connector configuration
1525 * @fb_helper: fb_helper device struct
1526 * @bpp_sel: bpp value to use for the framebuffer configuration
1528 * Scans the CRTCs and connectors and tries to put together an initial setup.
1529 * At the moment, this is a cloned configuration across all heads with
1530 * a new framebuffer object as the backing store.
1532 * Note that this also registers the fbdev and so allows userspace to call into
1533 * the driver through the fbdev interfaces.
1535 * This function will call down into the ->fb_probe callback to let
1536 * the driver allocate and initialize the fbdev info structure and the drm
1537 * framebuffer used to back the fbdev. drm_fb_helper_fill_var() and
1538 * drm_fb_helper_fill_fix() are provided as helpers to setup simple default
1539 * values for the fbdev info structure.
1542 * Zero if everything went ok, nonzero otherwise.
1544 bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
1546 struct drm_device *dev = fb_helper->dev;
1549 drm_fb_helper_parse_command_line(fb_helper);
1551 mutex_lock(&dev->mode_config.mutex);
1552 count = drm_fb_helper_probe_connector_modes(fb_helper,
1553 dev->mode_config.max_width,
1554 dev->mode_config.max_height);
1555 mutex_unlock(&dev->mode_config.mutex);
1557 * we shouldn't end up with no modes here.
1560 dev_info(fb_helper->dev->dev, "No connectors reported connected with modes\n");
1562 drm_setup_crtcs(fb_helper);
1564 return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
1566 EXPORT_SYMBOL(drm_fb_helper_initial_config);
1569 * drm_fb_helper_hotplug_event - respond to a hotplug notification by
1570 * probing all the outputs attached to the fb
1571 * @fb_helper: the drm_fb_helper
1573 * Scan the connectors attached to the fb_helper and try to put together a
1574 * setup after *notification of a change in output configuration.
1576 * Called at runtime, takes the mode config locks to be able to check/change the
1577 * modeset configuration. Must be run from process context (which usually means
1578 * either the output polling work or a work item launched from the driver's
1579 * hotplug interrupt).
1581 * Note that the driver must ensure that this is only called _after_ the fb has
1582 * been fully set up, i.e. after the call to drm_fb_helper_initial_config.
1585 * 0 on success and a non-zero error code otherwise.
1587 int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
1589 struct drm_device *dev = fb_helper->dev;
1590 u32 max_width, max_height;
1595 mutex_lock(&fb_helper->dev->mode_config.mutex);
1596 if (!drm_fb_helper_is_bound(fb_helper)) {
1597 fb_helper->delayed_hotplug = true;
1598 mutex_unlock(&fb_helper->dev->mode_config.mutex);
1601 DRM_DEBUG_KMS("\n");
1603 max_width = fb_helper->fb->width;
1604 max_height = fb_helper->fb->height;
1606 drm_fb_helper_probe_connector_modes(fb_helper, max_width, max_height);
1607 mutex_unlock(&fb_helper->dev->mode_config.mutex);
1609 drm_modeset_lock_all(dev);
1610 drm_setup_crtcs(fb_helper);
1611 drm_modeset_unlock_all(dev);
1612 drm_fb_helper_set_par(fb_helper->fbdev);
1616 EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
1618 /* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
1619 * but the module doesn't depend on any fb console symbols. At least
1620 * attempt to load fbcon to avoid leaving the system without a usable console.
1622 #if defined(CONFIG_FRAMEBUFFER_CONSOLE_MODULE) && !defined(CONFIG_EXPERT)
1623 static int __init drm_fb_helper_modinit(void)
1625 const char *name = "fbcon";
1626 struct module *fbcon;
1628 mutex_lock(&module_mutex);
1629 fbcon = find_module(name);
1630 mutex_unlock(&module_mutex);
1633 request_module_nowait(name);
1637 module_init(drm_fb_helper_modinit);