tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
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>
6 *
7 * May be copied or modified under the terms of the GNU General Public License
8 *
9 * video_detect.c:
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
13 *
14 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
15 * are available, video.ko should be used to handle the device.
16 *
17 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
18 * sony_acpi,... can take care about backlight brightness.
19 *
20 * Backlight drivers can use acpi_video_get_backlight_type() to determine
21 * which driver should handle the backlight.
22 *
23 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
24 * this file will not be compiled and acpi_video_get_backlight_type() will
25 * always return acpi_backlight_vendor.
26 */
27
28#include <linux/export.h>
29#include <linux/acpi.h>
30#include <linux/backlight.h>
31#include <linux/dmi.h>
32#include <linux/module.h>
33#include <linux/pci.h>
34#include <linux/types.h>
35#include <linux/workqueue.h>
36#include <acpi/video.h>
37
38void acpi_video_unregister_backlight(void);
39
40static bool backlight_notifier_registered;
41static struct notifier_block backlight_nb;
42static struct work_struct backlight_notify_work;
43
44static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
45static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
46
47static void acpi_video_parse_cmdline(void)
48{
49 if (!strcmp("vendor", acpi_video_backlight_string))
50 acpi_backlight_cmdline = acpi_backlight_vendor;
51 if (!strcmp("video", acpi_video_backlight_string))
52 acpi_backlight_cmdline = acpi_backlight_video;
53 if (!strcmp("native", acpi_video_backlight_string))
54 acpi_backlight_cmdline = acpi_backlight_native;
55 if (!strcmp("none", acpi_video_backlight_string))
56 acpi_backlight_cmdline = acpi_backlight_none;
57}
58
59static acpi_status
60find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
61{
62 struct acpi_device *acpi_dev = acpi_fetch_acpi_dev(handle);
63 long *cap = context;
64 struct pci_dev *dev;
65
66 static const struct acpi_device_id video_ids[] = {
67 {ACPI_VIDEO_HID, 0},
68 {"", 0},
69 };
70
71 if (acpi_dev && !acpi_match_device_ids(acpi_dev, video_ids)) {
72 dev = acpi_get_pci_dev(handle);
73 if (!dev)
74 return AE_OK;
75 pci_dev_put(dev);
76 *cap |= acpi_is_video_device(handle);
77 }
78 return AE_OK;
79}
80
81/* Force to use vendor driver when the ACPI device is known to be
82 * buggy */
83static int video_detect_force_vendor(const struct dmi_system_id *d)
84{
85 acpi_backlight_dmi = acpi_backlight_vendor;
86 return 0;
87}
88
89static int video_detect_force_video(const struct dmi_system_id *d)
90{
91 acpi_backlight_dmi = acpi_backlight_video;
92 return 0;
93}
94
95static int video_detect_force_native(const struct dmi_system_id *d)
96{
97 acpi_backlight_dmi = acpi_backlight_native;
98 return 0;
99}
100
101static int video_detect_force_none(const struct dmi_system_id *d)
102{
103 acpi_backlight_dmi = acpi_backlight_none;
104 return 0;
105}
106
107static const struct dmi_system_id video_detect_dmi_table[] = {
108 /* On Samsung X360, the BIOS will set a flag (VDRV) if generic
109 * ACPI backlight device is used. This flag will definitively break
110 * the backlight interface (even the vendor interface) until next
111 * reboot. It's why we should prevent video.ko from being used here
112 * and we can't rely on a later call to acpi_video_unregister().
113 */
114 {
115 .callback = video_detect_force_vendor,
116 /* X360 */
117 .matches = {
118 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
119 DMI_MATCH(DMI_PRODUCT_NAME, "X360"),
120 DMI_MATCH(DMI_BOARD_NAME, "X360"),
121 },
122 },
123 {
124 .callback = video_detect_force_vendor,
125 /* Asus UL30VT */
126 .matches = {
127 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
128 DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
129 },
130 },
131 {
132 .callback = video_detect_force_vendor,
133 /* Asus UL30A */
134 .matches = {
135 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
136 DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
137 },
138 },
139 {
140 .callback = video_detect_force_vendor,
141 /* GIGABYTE GB-BXBT-2807 */
142 .matches = {
143 DMI_MATCH(DMI_SYS_VENDOR, "GIGABYTE"),
144 DMI_MATCH(DMI_PRODUCT_NAME, "GB-BXBT-2807"),
145 },
146 },
147 {
148 .callback = video_detect_force_vendor,
149 /* Sony VPCEH3U1E */
150 .matches = {
151 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
152 DMI_MATCH(DMI_PRODUCT_NAME, "VPCEH3U1E"),
153 },
154 },
155 {
156 .callback = video_detect_force_vendor,
157 /* Xiaomi Mi Pad 2 */
158 .matches = {
159 DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
160 DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
161 },
162 },
163
164 /*
165 * These models have a working acpi_video backlight control, and using
166 * native backlight causes a regression where backlight does not work
167 * when userspace is not handling brightness key events. Disable
168 * native_backlight on these to fix this:
169 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
170 */
171 {
172 .callback = video_detect_force_video,
173 /* ThinkPad T420 */
174 .matches = {
175 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
176 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
177 },
178 },
179 {
180 .callback = video_detect_force_video,
181 /* ThinkPad T520 */
182 .matches = {
183 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
184 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
185 },
186 },
187 {
188 .callback = video_detect_force_video,
189 /* ThinkPad X201s */
190 .matches = {
191 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
192 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
193 },
194 },
195 {
196 .callback = video_detect_force_video,
197 /* ThinkPad X201T */
198 .matches = {
199 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
200 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201T"),
201 },
202 },
203
204 /* The native backlight controls do not work on some older machines */
205 {
206 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
207 .callback = video_detect_force_video,
208 /* HP ENVY 15 Notebook */
209 .matches = {
210 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
211 DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
212 },
213 },
214 {
215 .callback = video_detect_force_video,
216 /* SAMSUNG 870Z5E/880Z5E/680Z5E */
217 .matches = {
218 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
219 DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
220 },
221 },
222 {
223 .callback = video_detect_force_video,
224 /* SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V */
225 .matches = {
226 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
227 DMI_MATCH(DMI_PRODUCT_NAME,
228 "370R4E/370R4V/370R5E/3570RE/370R5V"),
229 },
230 },
231 {
232 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
233 .callback = video_detect_force_video,
234 /* SAMSUNG 3570R/370R/470R/450R/510R/4450RV */
235 .matches = {
236 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
237 DMI_MATCH(DMI_PRODUCT_NAME,
238 "3570R/370R/470R/450R/510R/4450RV"),
239 },
240 },
241 {
242 /* https://bugzilla.redhat.com/show_bug.cgi?id=1557060 */
243 .callback = video_detect_force_video,
244 /* SAMSUNG 670Z5E */
245 .matches = {
246 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
247 DMI_MATCH(DMI_PRODUCT_NAME, "670Z5E"),
248 },
249 },
250 {
251 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
252 .callback = video_detect_force_video,
253 /* SAMSUNG 730U3E/740U3E */
254 .matches = {
255 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
256 DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
257 },
258 },
259 {
260 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
261 .callback = video_detect_force_video,
262 /* SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D */
263 .matches = {
264 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
265 DMI_MATCH(DMI_PRODUCT_NAME,
266 "900X3C/900X3D/900X3E/900X4C/900X4D"),
267 },
268 },
269 {
270 /* https://bugzilla.redhat.com/show_bug.cgi?id=1272633 */
271 .callback = video_detect_force_video,
272 /* Dell XPS14 L421X */
273 .matches = {
274 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
275 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
276 },
277 },
278 {
279 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
280 .callback = video_detect_force_video,
281 /* Dell XPS15 L521X */
282 .matches = {
283 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
284 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
285 },
286 },
287 {
288 /* https://bugzilla.kernel.org/show_bug.cgi?id=108971 */
289 .callback = video_detect_force_video,
290 /* SAMSUNG 530U4E/540U4E */
291 .matches = {
292 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
293 DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
294 },
295 },
296 /* https://bugs.launchpad.net/bugs/1894667 */
297 {
298 .callback = video_detect_force_video,
299 /* HP 635 Notebook */
300 .matches = {
301 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
302 DMI_MATCH(DMI_PRODUCT_NAME, "HP 635 Notebook PC"),
303 },
304 },
305
306 /* Non win8 machines which need native backlight nevertheless */
307 {
308 /* https://bugzilla.redhat.com/show_bug.cgi?id=1201530 */
309 .callback = video_detect_force_native,
310 /* Lenovo Ideapad S405 */
311 .matches = {
312 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
313 DMI_MATCH(DMI_BOARD_NAME, "Lenovo IdeaPad S405"),
314 },
315 },
316 {
317 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
318 .callback = video_detect_force_native,
319 /* Lenovo Ideapad Z570 */
320 .matches = {
321 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
322 DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
323 },
324 },
325 {
326 .callback = video_detect_force_native,
327 /* Lenovo E41-25 */
328 .matches = {
329 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
330 DMI_MATCH(DMI_PRODUCT_NAME, "81FS"),
331 },
332 },
333 {
334 .callback = video_detect_force_native,
335 /* Lenovo E41-45 */
336 .matches = {
337 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
338 DMI_MATCH(DMI_PRODUCT_NAME, "82BK"),
339 },
340 },
341 {
342 /* https://bugzilla.redhat.com/show_bug.cgi?id=1217249 */
343 .callback = video_detect_force_native,
344 /* Apple MacBook Pro 12,1 */
345 .matches = {
346 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
347 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
348 },
349 },
350 {
351 .callback = video_detect_force_native,
352 /* Dell Inspiron N4010 */
353 .matches = {
354 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
355 DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron N4010"),
356 },
357 },
358 {
359 .callback = video_detect_force_native,
360 /* Dell Vostro V131 */
361 .matches = {
362 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
363 DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
364 },
365 },
366 {
367 /* https://bugzilla.redhat.com/show_bug.cgi?id=1123661 */
368 .callback = video_detect_force_native,
369 /* Dell XPS 17 L702X */
370 .matches = {
371 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
372 DMI_MATCH(DMI_PRODUCT_NAME, "Dell System XPS L702X"),
373 },
374 },
375 {
376 .callback = video_detect_force_native,
377 /* Dell Precision 7510 */
378 .matches = {
379 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
380 DMI_MATCH(DMI_PRODUCT_NAME, "Precision 7510"),
381 },
382 },
383 {
384 .callback = video_detect_force_native,
385 /* Acer Aspire 5738z */
386 .matches = {
387 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
388 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5738"),
389 DMI_MATCH(DMI_BOARD_NAME, "JV50"),
390 },
391 },
392 {
393 /* https://bugzilla.kernel.org/show_bug.cgi?id=207835 */
394 .callback = video_detect_force_native,
395 /* Acer TravelMate 5735Z */
396 .matches = {
397 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
398 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 5735Z"),
399 DMI_MATCH(DMI_BOARD_NAME, "BA51_MV"),
400 },
401 },
402 {
403 .callback = video_detect_force_native,
404 /* ASUSTeK COMPUTER INC. GA401 */
405 .matches = {
406 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
407 DMI_MATCH(DMI_PRODUCT_NAME, "GA401"),
408 },
409 },
410 {
411 .callback = video_detect_force_native,
412 /* ASUSTeK COMPUTER INC. GA502 */
413 .matches = {
414 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
415 DMI_MATCH(DMI_PRODUCT_NAME, "GA502"),
416 },
417 },
418 {
419 .callback = video_detect_force_native,
420 /* ASUSTeK COMPUTER INC. GA503 */
421 .matches = {
422 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
423 DMI_MATCH(DMI_PRODUCT_NAME, "GA503"),
424 },
425 },
426 /*
427 * Clevo NL5xRU and NL5xNU/TUXEDO Aura 15 Gen1 and Gen2 have both a
428 * working native and video interface. However the default detection
429 * mechanism first registers the video interface before unregistering
430 * it again and switching to the native interface during boot. This
431 * results in a dangling SBIOS request for backlight change for some
432 * reason, causing the backlight to switch to ~2% once per boot on the
433 * first power cord connect or disconnect event. Setting the native
434 * interface explicitly circumvents this buggy behaviour, by avoiding
435 * the unregistering process.
436 */
437 {
438 .callback = video_detect_force_native,
439 .ident = "Clevo NL5xRU",
440 .matches = {
441 DMI_MATCH(DMI_BOARD_NAME, "NL5xRU"),
442 },
443 },
444 {
445 .callback = video_detect_force_native,
446 .ident = "Clevo NL5xRU",
447 .matches = {
448 DMI_MATCH(DMI_SYS_VENDOR, "TUXEDO"),
449 DMI_MATCH(DMI_BOARD_NAME, "AURA1501"),
450 },
451 },
452 {
453 .callback = video_detect_force_native,
454 .ident = "Clevo NL5xRU",
455 .matches = {
456 DMI_MATCH(DMI_SYS_VENDOR, "TUXEDO"),
457 DMI_MATCH(DMI_BOARD_NAME, "EDUBOOK1502"),
458 },
459 },
460 {
461 .callback = video_detect_force_native,
462 .ident = "Clevo NL5xNU",
463 .matches = {
464 DMI_MATCH(DMI_BOARD_NAME, "NL5xNU"),
465 },
466 },
467 /*
468 * The TongFang PF5PU1G, PF4NU1F, PF5NU1G, and PF5LUXG/TUXEDO BA15 Gen10,
469 * Pulse 14/15 Gen1, and Pulse 15 Gen2 have the same problem as the Clevo
470 * NL5xRU and NL5xNU/TUXEDO Aura 15 Gen1 and Gen2. See the description
471 * above.
472 */
473 {
474 .callback = video_detect_force_native,
475 .ident = "TongFang PF5PU1G",
476 .matches = {
477 DMI_MATCH(DMI_BOARD_NAME, "PF5PU1G"),
478 },
479 },
480 {
481 .callback = video_detect_force_native,
482 .ident = "TongFang PF4NU1F",
483 .matches = {
484 DMI_MATCH(DMI_BOARD_NAME, "PF4NU1F"),
485 },
486 },
487 {
488 .callback = video_detect_force_native,
489 .ident = "TongFang PF4NU1F",
490 .matches = {
491 DMI_MATCH(DMI_SYS_VENDOR, "TUXEDO"),
492 DMI_MATCH(DMI_BOARD_NAME, "PULSE1401"),
493 },
494 },
495 {
496 .callback = video_detect_force_native,
497 .ident = "TongFang PF5NU1G",
498 .matches = {
499 DMI_MATCH(DMI_BOARD_NAME, "PF5NU1G"),
500 },
501 },
502 {
503 .callback = video_detect_force_native,
504 .ident = "TongFang PF5NU1G",
505 .matches = {
506 DMI_MATCH(DMI_SYS_VENDOR, "TUXEDO"),
507 DMI_MATCH(DMI_BOARD_NAME, "PULSE1501"),
508 },
509 },
510 {
511 .callback = video_detect_force_native,
512 .ident = "TongFang PF5LUXG",
513 .matches = {
514 DMI_MATCH(DMI_BOARD_NAME, "PF5LUXG"),
515 },
516 },
517 /*
518 * Desktops which falsely report a backlight and which our heuristics
519 * for this do not catch.
520 */
521 {
522 .callback = video_detect_force_none,
523 /* Dell OptiPlex 9020M */
524 .matches = {
525 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
526 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 9020M"),
527 },
528 },
529 {
530 .callback = video_detect_force_none,
531 /* MSI MS-7721 */
532 .matches = {
533 DMI_MATCH(DMI_SYS_VENDOR, "MSI"),
534 DMI_MATCH(DMI_PRODUCT_NAME, "MS-7721"),
535 },
536 },
537 { },
538};
539
540/* This uses a workqueue to avoid various locking ordering issues */
541static void acpi_video_backlight_notify_work(struct work_struct *work)
542{
543 if (acpi_video_get_backlight_type() != acpi_backlight_video)
544 acpi_video_unregister_backlight();
545}
546
547static int acpi_video_backlight_notify(struct notifier_block *nb,
548 unsigned long val, void *bd)
549{
550 struct backlight_device *backlight = bd;
551
552 /* A raw bl registering may change video -> native */
553 if (backlight->props.type == BACKLIGHT_RAW &&
554 val == BACKLIGHT_REGISTERED)
555 schedule_work(&backlight_notify_work);
556
557 return NOTIFY_OK;
558}
559
560/*
561 * Determine which type of backlight interface to use on this system,
562 * First check cmdline, then dmi quirks, then do autodetect.
563 *
564 * The autodetect order is:
565 * 1) Is the acpi-video backlight interface supported ->
566 * no, use a vendor interface
567 * 2) Is this a win8 "ready" BIOS and do we have a native interface ->
568 * yes, use a native interface
569 * 3) Else use the acpi-video interface
570 *
571 * Arguably the native on win8 check should be done first, but that would
572 * be a behavior change, which may causes issues.
573 */
574enum acpi_backlight_type acpi_video_get_backlight_type(void)
575{
576 static DEFINE_MUTEX(init_mutex);
577 static bool init_done;
578 static long video_caps;
579
580 /* Parse cmdline, dmi and acpi only once */
581 mutex_lock(&init_mutex);
582 if (!init_done) {
583 acpi_video_parse_cmdline();
584 dmi_check_system(video_detect_dmi_table);
585 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
586 ACPI_UINT32_MAX, find_video, NULL,
587 &video_caps, NULL);
588 INIT_WORK(&backlight_notify_work,
589 acpi_video_backlight_notify_work);
590 backlight_nb.notifier_call = acpi_video_backlight_notify;
591 backlight_nb.priority = 0;
592 if (backlight_register_notifier(&backlight_nb) == 0)
593 backlight_notifier_registered = true;
594 init_done = true;
595 }
596 mutex_unlock(&init_mutex);
597
598 if (acpi_backlight_cmdline != acpi_backlight_undef)
599 return acpi_backlight_cmdline;
600
601 if (acpi_backlight_dmi != acpi_backlight_undef)
602 return acpi_backlight_dmi;
603
604 if (!(video_caps & ACPI_VIDEO_BACKLIGHT))
605 return acpi_backlight_vendor;
606
607 if (acpi_osi_is_win8() && backlight_device_get_by_type(BACKLIGHT_RAW))
608 return acpi_backlight_native;
609
610 return acpi_backlight_video;
611}
612EXPORT_SYMBOL(acpi_video_get_backlight_type);
613
614/*
615 * Set the preferred backlight interface type based on DMI info.
616 * This function allows DMI blacklists to be implemented by external
617 * platform drivers instead of putting a big blacklist in video_detect.c
618 */
619void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
620{
621 acpi_backlight_dmi = type;
622 /* Remove acpi-video backlight interface if it is no longer desired */
623 if (acpi_video_get_backlight_type() != acpi_backlight_video)
624 acpi_video_unregister_backlight();
625}
626EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);
627
628void __exit acpi_video_detect_exit(void)
629{
630 if (backlight_notifier_registered)
631 backlight_unregister_notifier(&backlight_nb);
632}