2 * Copyright (C) 2015 Red Hat Inc.
3 * Hans de Goede <hdegoede@redhat.com>
4 * Copyright (C) 2008 SuSE Linux Products GmbH
5 * Thomas Renninger <trenn@suse.de>
7 * May be copied or modified under the terms of the GNU General Public License
10 * After PCI devices are glued with ACPI devices
11 * acpi_get_pci_dev() can be called to identify ACPI graphics
12 * devices for which a real graphics card is plugged in
14 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
15 * are available, video.ko should be used to handle the device.
17 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
18 * sony_acpi,... can take care about backlight brightness.
20 * Backlight drivers can use acpi_video_get_backlight_type() to determine which
21 * driver should handle the backlight. RAW/GPU-driver backlight drivers must
22 * use the acpi_video_backlight_use_native() helper for this.
24 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
25 * this file will not be compiled and acpi_video_get_backlight_type() will
26 * always return acpi_backlight_vendor.
29 #include <linux/export.h>
30 #include <linux/acpi.h>
31 #include <linux/apple-gmux.h>
32 #include <linux/backlight.h>
33 #include <linux/dmi.h>
34 #include <linux/module.h>
35 #include <linux/pci.h>
36 #include <linux/platform_data/x86/nvidia-wmi-ec-backlight.h>
37 #include <linux/types.h>
38 #include <linux/workqueue.h>
39 #include <acpi/video.h>
41 static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
42 static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
44 static void acpi_video_parse_cmdline(void)
46 if (!strcmp("vendor", acpi_video_backlight_string))
47 acpi_backlight_cmdline = acpi_backlight_vendor;
48 if (!strcmp("video", acpi_video_backlight_string))
49 acpi_backlight_cmdline = acpi_backlight_video;
50 if (!strcmp("native", acpi_video_backlight_string))
51 acpi_backlight_cmdline = acpi_backlight_native;
52 if (!strcmp("none", acpi_video_backlight_string))
53 acpi_backlight_cmdline = acpi_backlight_none;
57 find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
59 struct acpi_device *acpi_dev = acpi_fetch_acpi_dev(handle);
63 static const struct acpi_device_id video_ids[] = {
68 if (acpi_dev && !acpi_match_device_ids(acpi_dev, video_ids)) {
69 dev = acpi_get_pci_dev(handle);
73 *cap |= acpi_is_video_device(handle);
78 /* This depends on ACPI_WMI which is X86 only */
80 static bool nvidia_wmi_ec_supported(void)
82 struct wmi_brightness_args args = {
83 .mode = WMI_BRIGHTNESS_MODE_GET,
87 struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
90 status = wmi_evaluate_method(WMI_BRIGHTNESS_GUID, 0,
91 WMI_BRIGHTNESS_METHOD_SOURCE, &buf, &buf);
92 if (ACPI_FAILURE(status))
96 * If brightness is handled by the EC then nvidia-wmi-ec-backlight
97 * should be used, else the GPU driver(s) should be used.
99 return args.ret == WMI_BRIGHTNESS_SOURCE_EC;
102 static bool nvidia_wmi_ec_supported(void)
108 /* Force to use vendor driver when the ACPI device is known to be
110 static int video_detect_force_vendor(const struct dmi_system_id *d)
112 acpi_backlight_dmi = acpi_backlight_vendor;
116 static int video_detect_force_video(const struct dmi_system_id *d)
118 acpi_backlight_dmi = acpi_backlight_video;
122 static int video_detect_force_native(const struct dmi_system_id *d)
124 acpi_backlight_dmi = acpi_backlight_native;
128 static int video_detect_force_none(const struct dmi_system_id *d)
130 acpi_backlight_dmi = acpi_backlight_none;
134 static const struct dmi_system_id video_detect_dmi_table[] = {
136 * Models which should use the vendor backlight interface,
137 * because of broken ACPI video backlight control.
140 /* https://bugzilla.redhat.com/show_bug.cgi?id=1128309 */
141 .callback = video_detect_force_vendor,
144 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
145 DMI_MATCH(DMI_PRODUCT_NAME, "KAV80"),
149 .callback = video_detect_force_vendor,
152 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
153 DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
157 .callback = video_detect_force_vendor,
160 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
161 DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
165 .callback = video_detect_force_vendor,
168 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
169 DMI_MATCH(DMI_PRODUCT_NAME, "X55U"),
173 .callback = video_detect_force_vendor,
176 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
177 DMI_MATCH(DMI_PRODUCT_NAME, "X101CH"),
181 .callback = video_detect_force_vendor,
184 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
185 DMI_MATCH(DMI_PRODUCT_NAME, "X401U"),
189 .callback = video_detect_force_vendor,
192 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
193 DMI_MATCH(DMI_PRODUCT_NAME, "X501U"),
197 .callback = video_detect_force_vendor,
200 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
201 DMI_MATCH(DMI_PRODUCT_NAME, "1015CX"),
205 .callback = video_detect_force_vendor,
206 /* Samsung N150/N210/N220 */
208 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
209 DMI_MATCH(DMI_PRODUCT_NAME, "N150/N210/N220"),
210 DMI_MATCH(DMI_BOARD_NAME, "N150/N210/N220"),
214 .callback = video_detect_force_vendor,
215 /* Samsung NF110/NF210/NF310 */
217 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
218 DMI_MATCH(DMI_PRODUCT_NAME, "NF110/NF210/NF310"),
219 DMI_MATCH(DMI_BOARD_NAME, "NF110/NF210/NF310"),
223 .callback = video_detect_force_vendor,
226 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
227 DMI_MATCH(DMI_PRODUCT_NAME, "NC210/NC110"),
228 DMI_MATCH(DMI_BOARD_NAME, "NC210/NC110"),
232 .callback = video_detect_force_vendor,
233 /* Xiaomi Mi Pad 2 */
235 DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
236 DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
241 * Models which should use the vendor backlight interface,
242 * because of broken native backlight control.
245 .callback = video_detect_force_vendor,
246 /* Sony Vaio PCG-FRV35 */
248 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
249 DMI_MATCH(DMI_PRODUCT_NAME, "PCG-FRV35"),
254 * Toshiba models with Transflective display, these need to use
255 * the toshiba_acpi vendor driver for proper Transflective handling.
258 .callback = video_detect_force_vendor,
260 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
261 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R500"),
265 .callback = video_detect_force_vendor,
267 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
268 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R600"),
273 * These models have a working acpi_video backlight control, and using
274 * native backlight causes a regression where backlight does not work
275 * when userspace is not handling brightness key events. Disable
276 * native_backlight on these to fix this:
277 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
280 .callback = video_detect_force_video,
283 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
284 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
288 .callback = video_detect_force_video,
291 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
292 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
296 .callback = video_detect_force_video,
299 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
300 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
304 .callback = video_detect_force_video,
307 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
308 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201T"),
312 /* The native backlight controls do not work on some older machines */
314 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
315 .callback = video_detect_force_video,
316 /* HP ENVY 15 Notebook */
318 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
319 DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
323 .callback = video_detect_force_video,
324 /* SAMSUNG 870Z5E/880Z5E/680Z5E */
326 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
327 DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
331 .callback = video_detect_force_video,
332 /* SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V */
334 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
335 DMI_MATCH(DMI_PRODUCT_NAME,
336 "370R4E/370R4V/370R5E/3570RE/370R5V"),
340 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
341 .callback = video_detect_force_video,
342 /* SAMSUNG 3570R/370R/470R/450R/510R/4450RV */
344 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
345 DMI_MATCH(DMI_PRODUCT_NAME,
346 "3570R/370R/470R/450R/510R/4450RV"),
350 /* https://bugzilla.redhat.com/show_bug.cgi?id=1557060 */
351 .callback = video_detect_force_video,
354 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
355 DMI_MATCH(DMI_PRODUCT_NAME, "670Z5E"),
359 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
360 .callback = video_detect_force_video,
361 /* SAMSUNG 730U3E/740U3E */
363 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
364 DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
368 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
369 .callback = video_detect_force_video,
370 /* SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D */
372 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
373 DMI_MATCH(DMI_PRODUCT_NAME,
374 "900X3C/900X3D/900X3E/900X4C/900X4D"),
378 /* https://bugzilla.redhat.com/show_bug.cgi?id=1272633 */
379 .callback = video_detect_force_video,
380 /* Dell XPS14 L421X */
382 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
383 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
387 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
388 .callback = video_detect_force_video,
389 /* Dell XPS15 L521X */
391 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
392 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
396 /* https://bugzilla.kernel.org/show_bug.cgi?id=108971 */
397 .callback = video_detect_force_video,
398 /* SAMSUNG 530U4E/540U4E */
400 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
401 DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
404 /* https://bugs.launchpad.net/bugs/1894667 */
406 .callback = video_detect_force_video,
407 /* HP 635 Notebook */
409 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
410 DMI_MATCH(DMI_PRODUCT_NAME, "HP 635 Notebook PC"),
414 /* Non win8 machines which need native backlight nevertheless */
416 /* https://bugzilla.redhat.com/show_bug.cgi?id=1201530 */
417 .callback = video_detect_force_native,
418 /* Lenovo Ideapad S405 */
420 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
421 DMI_MATCH(DMI_BOARD_NAME, "Lenovo IdeaPad S405"),
425 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
426 .callback = video_detect_force_native,
427 /* Lenovo Ideapad Z570 */
429 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
430 DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
434 .callback = video_detect_force_native,
437 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
438 DMI_MATCH(DMI_PRODUCT_NAME, "81FS"),
442 .callback = video_detect_force_native,
445 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
446 DMI_MATCH(DMI_PRODUCT_NAME, "82BK"),
450 /* https://bugzilla.redhat.com/show_bug.cgi?id=1217249 */
451 .callback = video_detect_force_native,
452 /* Apple MacBook Pro 12,1 */
454 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
455 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
459 .callback = video_detect_force_native,
460 /* Dell Inspiron N4010 */
462 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
463 DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron N4010"),
467 .callback = video_detect_force_native,
468 /* Dell Vostro V131 */
470 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
471 DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
475 /* https://bugzilla.redhat.com/show_bug.cgi?id=1123661 */
476 .callback = video_detect_force_native,
477 /* Dell XPS 17 L702X */
479 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
480 DMI_MATCH(DMI_PRODUCT_NAME, "Dell System XPS L702X"),
484 .callback = video_detect_force_native,
485 /* Dell Precision 7510 */
487 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
488 DMI_MATCH(DMI_PRODUCT_NAME, "Precision 7510"),
492 .callback = video_detect_force_native,
493 /* Acer Aspire 5738z */
495 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
496 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5738"),
497 DMI_MATCH(DMI_BOARD_NAME, "JV50"),
501 /* https://bugzilla.redhat.com/show_bug.cgi?id=1012674 */
502 .callback = video_detect_force_native,
503 /* Acer Aspire 5741 */
505 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
506 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5741"),
510 /* https://bugzilla.kernel.org/show_bug.cgi?id=42993 */
511 .callback = video_detect_force_native,
512 /* Acer Aspire 5750 */
514 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
515 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5750"),
519 /* https://bugzilla.kernel.org/show_bug.cgi?id=42833 */
520 .callback = video_detect_force_native,
521 /* Acer Extensa 5235 */
523 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
524 DMI_MATCH(DMI_PRODUCT_NAME, "Extensa 5235"),
528 .callback = video_detect_force_native,
529 /* Acer TravelMate 4750 */
531 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
532 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 4750"),
536 /* https://bugzilla.kernel.org/show_bug.cgi?id=207835 */
537 .callback = video_detect_force_native,
538 /* Acer TravelMate 5735Z */
540 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
541 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 5735Z"),
542 DMI_MATCH(DMI_BOARD_NAME, "BA51_MV"),
546 /* https://bugzilla.kernel.org/show_bug.cgi?id=36322 */
547 .callback = video_detect_force_native,
548 /* Acer TravelMate 5760 */
550 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
551 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 5760"),
555 .callback = video_detect_force_native,
556 /* ASUSTeK COMPUTER INC. GA401 */
558 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
559 DMI_MATCH(DMI_PRODUCT_NAME, "GA401"),
563 .callback = video_detect_force_native,
564 /* ASUSTeK COMPUTER INC. GA502 */
566 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
567 DMI_MATCH(DMI_PRODUCT_NAME, "GA502"),
571 .callback = video_detect_force_native,
572 /* ASUSTeK COMPUTER INC. GA503 */
574 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
575 DMI_MATCH(DMI_PRODUCT_NAME, "GA503"),
579 .callback = video_detect_force_native,
582 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
583 DMI_MATCH(DMI_PRODUCT_NAME, "UX303UB"),
587 .callback = video_detect_force_native,
590 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
591 DMI_MATCH(DMI_PRODUCT_NAME, "N150P"),
592 DMI_MATCH(DMI_BOARD_NAME, "N150P"),
596 .callback = video_detect_force_native,
597 /* Samsung N145P/N250P/N260P */
599 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
600 DMI_MATCH(DMI_PRODUCT_NAME, "N145P/N250P/N260P"),
601 DMI_MATCH(DMI_BOARD_NAME, "N145P/N250P/N260P"),
605 .callback = video_detect_force_native,
608 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
609 DMI_MATCH(DMI_PRODUCT_NAME, "N250P"),
610 DMI_MATCH(DMI_BOARD_NAME, "N250P"),
614 /* https://bugzilla.kernel.org/show_bug.cgi?id=202401 */
615 .callback = video_detect_force_native,
616 /* Sony Vaio VPCEH3U1E */
618 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
619 DMI_MATCH(DMI_PRODUCT_NAME, "VPCEH3U1E"),
623 .callback = video_detect_force_native,
624 /* Sony Vaio VPCY11S1E */
626 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
627 DMI_MATCH(DMI_PRODUCT_NAME, "VPCY11S1E"),
632 * These Toshibas have a broken acpi-video interface for brightness
633 * control. They also have an issue where the panel is off after
634 * suspend until a special firmware call is made to turn it back
635 * on. This is handled by the toshiba_acpi kernel module, so that
636 * module must be enabled for these models to work correctly.
639 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
640 .callback = video_detect_force_native,
641 /* Toshiba Portégé R700 */
643 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
644 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R700"),
648 /* Portégé: https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
649 /* Satellite: https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
650 .callback = video_detect_force_native,
651 /* Toshiba Satellite/Portégé R830 */
653 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
654 DMI_MATCH(DMI_PRODUCT_NAME, "R830"),
658 .callback = video_detect_force_native,
659 /* Toshiba Satellite/Portégé Z830 */
661 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
662 DMI_MATCH(DMI_PRODUCT_NAME, "Z830"),
667 * Models which have nvidia-ec-wmi support, but should not use it.
668 * Note this indicates a likely firmware bug on these models and should
669 * be revisited if/when Linux gets support for dynamic mux mode.
672 .callback = video_detect_force_native,
675 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
676 DMI_MATCH(DMI_PRODUCT_NAME, "Dell G15 5515"),
681 * Desktops which falsely report a backlight and which our heuristics
682 * for this do not catch.
685 .callback = video_detect_force_none,
686 /* Dell OptiPlex 9020M */
688 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
689 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 9020M"),
693 .callback = video_detect_force_none,
694 /* GIGABYTE GB-BXBT-2807 */
696 DMI_MATCH(DMI_SYS_VENDOR, "GIGABYTE"),
697 DMI_MATCH(DMI_PRODUCT_NAME, "GB-BXBT-2807"),
701 .callback = video_detect_force_none,
704 DMI_MATCH(DMI_SYS_VENDOR, "MSI"),
705 DMI_MATCH(DMI_PRODUCT_NAME, "MS-7721"),
711 static bool google_cros_ec_present(void)
713 return acpi_dev_found("GOOG0004") || acpi_dev_found("GOOG000C");
717 * Determine which type of backlight interface to use on this system,
718 * First check cmdline, then dmi quirks, then do autodetect.
720 static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
722 static DEFINE_MUTEX(init_mutex);
723 static bool nvidia_wmi_ec_present;
724 static bool native_available;
725 static bool init_done;
726 static long video_caps;
728 /* Parse cmdline, dmi and acpi only once */
729 mutex_lock(&init_mutex);
731 acpi_video_parse_cmdline();
732 dmi_check_system(video_detect_dmi_table);
733 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
734 ACPI_UINT32_MAX, find_video, NULL,
736 nvidia_wmi_ec_present = nvidia_wmi_ec_supported();
740 native_available = true;
741 mutex_unlock(&init_mutex);
744 * The below heuristics / detection steps are in order of descending
745 * presedence. The commandline takes presedence over anything else.
747 if (acpi_backlight_cmdline != acpi_backlight_undef)
748 return acpi_backlight_cmdline;
750 /* DMI quirks override any autodetection. */
751 if (acpi_backlight_dmi != acpi_backlight_undef)
752 return acpi_backlight_dmi;
754 /* Special cases such as nvidia_wmi_ec and apple gmux. */
755 if (nvidia_wmi_ec_present)
756 return acpi_backlight_nvidia_wmi_ec;
758 if (apple_gmux_present())
759 return acpi_backlight_apple_gmux;
761 /* Chromebooks should always prefer native backlight control. */
762 if (google_cros_ec_present() && native_available)
763 return acpi_backlight_native;
765 /* On systems with ACPI video use either native or ACPI video. */
766 if (video_caps & ACPI_VIDEO_BACKLIGHT) {
768 * Windows 8 and newer no longer use the ACPI video interface,
769 * so it often does not work. If the ACPI tables are written
770 * for win8 and native brightness ctl is available, use that.
772 * The native check deliberately is inside the if acpi-video
773 * block on older devices without acpi-video support native
774 * is usually not the best choice.
776 if (acpi_osi_is_win8() && native_available)
777 return acpi_backlight_native;
779 return acpi_backlight_video;
782 /* No ACPI video (old hw), use vendor specific fw methods. */
783 return acpi_backlight_vendor;
786 enum acpi_backlight_type acpi_video_get_backlight_type(void)
788 return __acpi_video_get_backlight_type(false);
790 EXPORT_SYMBOL(acpi_video_get_backlight_type);
792 bool acpi_video_backlight_use_native(void)
795 * Call __acpi_video_get_backlight_type() to let it know that
796 * a native backlight is available.
798 __acpi_video_get_backlight_type(true);
801 * For now just always return true. There is a whole bunch of laptop
802 * models where (video_caps & ACPI_VIDEO_BACKLIGHT) is false causing
803 * __acpi_video_get_backlight_type() to return vendor, while these
804 * models only have a native backlight control.
808 EXPORT_SYMBOL(acpi_video_backlight_use_native);