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 /* https://bugzilla.redhat.com/show_bug.cgi?id=1128309 */
137 .callback = video_detect_force_vendor,
140 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
141 DMI_MATCH(DMI_PRODUCT_NAME, "KAV80"),
145 .callback = video_detect_force_vendor,
148 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
149 DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
153 .callback = video_detect_force_vendor,
156 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
157 DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
161 .callback = video_detect_force_vendor,
164 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
165 DMI_MATCH(DMI_PRODUCT_NAME, "X55U"),
169 .callback = video_detect_force_vendor,
172 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
173 DMI_MATCH(DMI_PRODUCT_NAME, "X101CH"),
177 .callback = video_detect_force_vendor,
180 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
181 DMI_MATCH(DMI_PRODUCT_NAME, "X401U"),
185 .callback = video_detect_force_vendor,
188 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
189 DMI_MATCH(DMI_PRODUCT_NAME, "X501U"),
193 .callback = video_detect_force_vendor,
196 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
197 DMI_MATCH(DMI_PRODUCT_NAME, "1015CX"),
201 .callback = video_detect_force_vendor,
202 /* Samsung N150/N210/N220 */
204 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
205 DMI_MATCH(DMI_PRODUCT_NAME, "N150/N210/N220"),
206 DMI_MATCH(DMI_BOARD_NAME, "N150/N210/N220"),
210 .callback = video_detect_force_vendor,
211 /* Samsung NF110/NF210/NF310 */
213 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
214 DMI_MATCH(DMI_PRODUCT_NAME, "NF110/NF210/NF310"),
215 DMI_MATCH(DMI_BOARD_NAME, "NF110/NF210/NF310"),
219 .callback = video_detect_force_vendor,
222 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
223 DMI_MATCH(DMI_PRODUCT_NAME, "NC210/NC110"),
224 DMI_MATCH(DMI_BOARD_NAME, "NC210/NC110"),
228 .callback = video_detect_force_vendor,
231 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
232 DMI_MATCH(DMI_PRODUCT_NAME, "VPCEH3U1E"),
236 .callback = video_detect_force_vendor,
237 /* Xiaomi Mi Pad 2 */
239 DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
240 DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
245 * Toshiba models with Transflective display, these need to use
246 * the toshiba_acpi vendor driver for proper Transflective handling.
249 .callback = video_detect_force_vendor,
251 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
252 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R500"),
256 .callback = video_detect_force_vendor,
258 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
259 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R600"),
264 * These models have a working acpi_video backlight control, and using
265 * native backlight causes a regression where backlight does not work
266 * when userspace is not handling brightness key events. Disable
267 * native_backlight on these to fix this:
268 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
271 .callback = video_detect_force_video,
274 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
275 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
279 .callback = video_detect_force_video,
282 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
283 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
287 .callback = video_detect_force_video,
290 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
291 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
295 .callback = video_detect_force_video,
298 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
299 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201T"),
303 /* The native backlight controls do not work on some older machines */
305 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
306 .callback = video_detect_force_video,
307 /* HP ENVY 15 Notebook */
309 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
310 DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
314 .callback = video_detect_force_video,
315 /* SAMSUNG 870Z5E/880Z5E/680Z5E */
317 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
318 DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
322 .callback = video_detect_force_video,
323 /* SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V */
325 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
326 DMI_MATCH(DMI_PRODUCT_NAME,
327 "370R4E/370R4V/370R5E/3570RE/370R5V"),
331 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
332 .callback = video_detect_force_video,
333 /* SAMSUNG 3570R/370R/470R/450R/510R/4450RV */
335 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
336 DMI_MATCH(DMI_PRODUCT_NAME,
337 "3570R/370R/470R/450R/510R/4450RV"),
341 /* https://bugzilla.redhat.com/show_bug.cgi?id=1557060 */
342 .callback = video_detect_force_video,
345 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
346 DMI_MATCH(DMI_PRODUCT_NAME, "670Z5E"),
350 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
351 .callback = video_detect_force_video,
352 /* SAMSUNG 730U3E/740U3E */
354 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
355 DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
359 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
360 .callback = video_detect_force_video,
361 /* SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D */
363 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
364 DMI_MATCH(DMI_PRODUCT_NAME,
365 "900X3C/900X3D/900X3E/900X4C/900X4D"),
369 /* https://bugzilla.redhat.com/show_bug.cgi?id=1272633 */
370 .callback = video_detect_force_video,
371 /* Dell XPS14 L421X */
373 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
374 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
378 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
379 .callback = video_detect_force_video,
380 /* Dell XPS15 L521X */
382 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
383 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
387 /* https://bugzilla.kernel.org/show_bug.cgi?id=108971 */
388 .callback = video_detect_force_video,
389 /* SAMSUNG 530U4E/540U4E */
391 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
392 DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
395 /* https://bugs.launchpad.net/bugs/1894667 */
397 .callback = video_detect_force_video,
398 /* HP 635 Notebook */
400 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
401 DMI_MATCH(DMI_PRODUCT_NAME, "HP 635 Notebook PC"),
405 /* Non win8 machines which need native backlight nevertheless */
407 /* https://bugzilla.redhat.com/show_bug.cgi?id=1201530 */
408 .callback = video_detect_force_native,
409 /* Lenovo Ideapad S405 */
411 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
412 DMI_MATCH(DMI_BOARD_NAME, "Lenovo IdeaPad S405"),
416 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
417 .callback = video_detect_force_native,
418 /* Lenovo Ideapad Z570 */
420 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
421 DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
425 .callback = video_detect_force_native,
428 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
429 DMI_MATCH(DMI_PRODUCT_NAME, "81FS"),
433 .callback = video_detect_force_native,
436 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
437 DMI_MATCH(DMI_PRODUCT_NAME, "82BK"),
441 /* https://bugzilla.redhat.com/show_bug.cgi?id=1217249 */
442 .callback = video_detect_force_native,
443 /* Apple MacBook Pro 12,1 */
445 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
446 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
450 .callback = video_detect_force_native,
451 /* Dell Inspiron N4010 */
453 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
454 DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron N4010"),
458 .callback = video_detect_force_native,
459 /* Dell Vostro V131 */
461 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
462 DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
466 /* https://bugzilla.redhat.com/show_bug.cgi?id=1123661 */
467 .callback = video_detect_force_native,
468 /* Dell XPS 17 L702X */
470 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
471 DMI_MATCH(DMI_PRODUCT_NAME, "Dell System XPS L702X"),
475 .callback = video_detect_force_native,
476 /* Dell Precision 7510 */
478 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
479 DMI_MATCH(DMI_PRODUCT_NAME, "Precision 7510"),
483 .callback = video_detect_force_native,
484 /* Acer Aspire 5738z */
486 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
487 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5738"),
488 DMI_MATCH(DMI_BOARD_NAME, "JV50"),
492 /* https://bugzilla.redhat.com/show_bug.cgi?id=1012674 */
493 .callback = video_detect_force_native,
494 /* Acer Aspire 5741 */
496 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
497 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5741"),
501 /* https://bugzilla.kernel.org/show_bug.cgi?id=42993 */
502 .callback = video_detect_force_native,
503 /* Acer Aspire 5750 */
505 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
506 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5750"),
510 /* https://bugzilla.kernel.org/show_bug.cgi?id=42833 */
511 .callback = video_detect_force_native,
512 /* Acer Extensa 5235 */
514 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
515 DMI_MATCH(DMI_PRODUCT_NAME, "Extensa 5235"),
519 .callback = video_detect_force_native,
520 /* Acer TravelMate 4750 */
522 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
523 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 4750"),
527 /* https://bugzilla.kernel.org/show_bug.cgi?id=207835 */
528 .callback = video_detect_force_native,
529 /* Acer TravelMate 5735Z */
531 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
532 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 5735Z"),
533 DMI_MATCH(DMI_BOARD_NAME, "BA51_MV"),
537 /* https://bugzilla.kernel.org/show_bug.cgi?id=36322 */
538 .callback = video_detect_force_native,
539 /* Acer TravelMate 5760 */
541 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
542 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 5760"),
546 .callback = video_detect_force_native,
547 /* ASUSTeK COMPUTER INC. GA401 */
549 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
550 DMI_MATCH(DMI_PRODUCT_NAME, "GA401"),
554 .callback = video_detect_force_native,
555 /* ASUSTeK COMPUTER INC. GA502 */
557 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
558 DMI_MATCH(DMI_PRODUCT_NAME, "GA502"),
562 .callback = video_detect_force_native,
563 /* ASUSTeK COMPUTER INC. GA503 */
565 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
566 DMI_MATCH(DMI_PRODUCT_NAME, "GA503"),
570 .callback = video_detect_force_native,
573 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
574 DMI_MATCH(DMI_PRODUCT_NAME, "UX303UB"),
578 .callback = video_detect_force_native,
581 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
582 DMI_MATCH(DMI_PRODUCT_NAME, "N150P"),
583 DMI_MATCH(DMI_BOARD_NAME, "N150P"),
587 .callback = video_detect_force_native,
588 /* Samsung N145P/N250P/N260P */
590 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
591 DMI_MATCH(DMI_PRODUCT_NAME, "N145P/N250P/N260P"),
592 DMI_MATCH(DMI_BOARD_NAME, "N145P/N250P/N260P"),
596 .callback = video_detect_force_native,
599 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
600 DMI_MATCH(DMI_PRODUCT_NAME, "N250P"),
601 DMI_MATCH(DMI_BOARD_NAME, "N250P"),
606 * These Toshibas have a broken acpi-video interface for brightness
607 * control. They also have an issue where the panel is off after
608 * suspend until a special firmware call is made to turn it back
609 * on. This is handled by the toshiba_acpi kernel module, so that
610 * module must be enabled for these models to work correctly.
613 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
614 .callback = video_detect_force_native,
615 /* Toshiba Portégé R700 */
617 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
618 DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R700"),
622 /* Portégé: https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
623 /* Satellite: https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
624 .callback = video_detect_force_native,
625 /* Toshiba Satellite/Portégé R830 */
627 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
628 DMI_MATCH(DMI_PRODUCT_NAME, "R830"),
632 .callback = video_detect_force_native,
633 /* Toshiba Satellite/Portégé Z830 */
635 DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
636 DMI_MATCH(DMI_PRODUCT_NAME, "Z830"),
641 * Models which have nvidia-ec-wmi support, but should not use it.
642 * Note this indicates a likely firmware bug on these models and should
643 * be revisited if/when Linux gets support for dynamic mux mode.
646 .callback = video_detect_force_native,
649 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
650 DMI_MATCH(DMI_PRODUCT_NAME, "Dell G15 5515"),
655 * Desktops which falsely report a backlight and which our heuristics
656 * for this do not catch.
659 .callback = video_detect_force_none,
660 /* Dell OptiPlex 9020M */
662 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
663 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 9020M"),
667 .callback = video_detect_force_none,
668 /* GIGABYTE GB-BXBT-2807 */
670 DMI_MATCH(DMI_SYS_VENDOR, "GIGABYTE"),
671 DMI_MATCH(DMI_PRODUCT_NAME, "GB-BXBT-2807"),
675 .callback = video_detect_force_none,
678 DMI_MATCH(DMI_SYS_VENDOR, "MSI"),
679 DMI_MATCH(DMI_PRODUCT_NAME, "MS-7721"),
685 static bool google_cros_ec_present(void)
687 return acpi_dev_found("GOOG0004") || acpi_dev_found("GOOG000C");
691 * Determine which type of backlight interface to use on this system,
692 * First check cmdline, then dmi quirks, then do autodetect.
694 static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
696 static DEFINE_MUTEX(init_mutex);
697 static bool nvidia_wmi_ec_present;
698 static bool native_available;
699 static bool init_done;
700 static long video_caps;
702 /* Parse cmdline, dmi and acpi only once */
703 mutex_lock(&init_mutex);
705 acpi_video_parse_cmdline();
706 dmi_check_system(video_detect_dmi_table);
707 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
708 ACPI_UINT32_MAX, find_video, NULL,
710 nvidia_wmi_ec_present = nvidia_wmi_ec_supported();
714 native_available = true;
715 mutex_unlock(&init_mutex);
718 * The below heuristics / detection steps are in order of descending
719 * presedence. The commandline takes presedence over anything else.
721 if (acpi_backlight_cmdline != acpi_backlight_undef)
722 return acpi_backlight_cmdline;
724 /* DMI quirks override any autodetection. */
725 if (acpi_backlight_dmi != acpi_backlight_undef)
726 return acpi_backlight_dmi;
728 /* Special cases such as nvidia_wmi_ec and apple gmux. */
729 if (nvidia_wmi_ec_present)
730 return acpi_backlight_nvidia_wmi_ec;
732 if (apple_gmux_present())
733 return acpi_backlight_apple_gmux;
735 /* Chromebooks should always prefer native backlight control. */
736 if (google_cros_ec_present() && native_available)
737 return acpi_backlight_native;
739 /* On systems with ACPI video use either native or ACPI video. */
740 if (video_caps & ACPI_VIDEO_BACKLIGHT) {
742 * Windows 8 and newer no longer use the ACPI video interface,
743 * so it often does not work. If the ACPI tables are written
744 * for win8 and native brightness ctl is available, use that.
746 * The native check deliberately is inside the if acpi-video
747 * block on older devices without acpi-video support native
748 * is usually not the best choice.
750 if (acpi_osi_is_win8() && native_available)
751 return acpi_backlight_native;
753 return acpi_backlight_video;
756 /* No ACPI video (old hw), use vendor specific fw methods. */
757 return acpi_backlight_vendor;
760 enum acpi_backlight_type acpi_video_get_backlight_type(void)
762 return __acpi_video_get_backlight_type(false);
764 EXPORT_SYMBOL(acpi_video_get_backlight_type);
766 bool acpi_video_backlight_use_native(void)
769 * Call __acpi_video_get_backlight_type() to let it know that
770 * a native backlight is available.
772 __acpi_video_get_backlight_type(true);
775 * For now just always return true. There is a whole bunch of laptop
776 * models where (video_caps & ACPI_VIDEO_BACKLIGHT) is false causing
777 * __acpi_video_get_backlight_type() to return vendor, while these
778 * models only have a native backlight control.
782 EXPORT_SYMBOL(acpi_video_backlight_use_native);