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1/*
2 * Copyright (C) 2008 SuSE Linux Products GmbH
3 * Thomas Renninger <trenn@suse.de>
4 *
5 * May be copied or modified under the terms of the GNU General Public License
6 *
7 * video_detect.c:
8 * Provides acpi_is_video_device() for early scanning of ACPI devices in scan.c
9 * There a Linux specific (Spec does not provide a HID for video devices) is
10 * assigned
11 *
12 * After PCI devices are glued with ACPI devices
13 * acpi_get_pci_dev() can be called to identify ACPI graphics
14 * devices for which a real graphics card is plugged in
15 *
16 * Now acpi_video_get_capabilities() can be called to check which
17 * capabilities the graphics cards plugged in support. The check for general
18 * video capabilities will be triggered by the first caller of
19 * acpi_video_get_capabilities(NULL); which will happen when the first
20 * backlight switching supporting driver calls:
21 * acpi_video_backlight_support();
22 *
23 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
24 * are available, video.ko should be used to handle the device.
25 *
26 * Otherwise vendor specific drivers like thinkpad_acpi, asus_acpi,
27 * sony_acpi,... can take care about backlight brightness.
28 *
29 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
30 * this file will not be compiled, acpi_video_get_capabilities() and
31 * acpi_video_backlight_support() will always return 0 and vendor specific
32 * drivers always can handle backlight.
33 *
34 */
35
36#include <linux/acpi.h>
37#include <linux/dmi.h>
38#include <linux/pci.h>
39
40#define PREFIX "ACPI: "
41
42ACPI_MODULE_NAME("video");
43#define _COMPONENT ACPI_VIDEO_COMPONENT
44
45static long acpi_video_support;
46static bool acpi_video_caps_checked;
47
48static acpi_status
49acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
50 void **retyurn_value)
51{
52 long *cap = context;
53 acpi_handle h_dummy;
54
55 if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
56 ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
57 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
58 "support\n"));
59 *cap |= ACPI_VIDEO_BACKLIGHT;
60 if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
61 printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
62 "cannot determine initial brightness\n");
63 /* We have backlight support, no need to scan further */
64 return AE_CTRL_TERMINATE;
65 }
66 return 0;
67}
68
69/* Returns true if the device is a video device which can be handled by
70 * video.ko.
71 * The device will get a Linux specific CID added in scan.c to
72 * identify the device as an ACPI graphics device
73 * Be aware that the graphics device may not be physically present
74 * Use acpi_video_get_capabilities() to detect general ACPI video
75 * capabilities of present cards
76 */
77long acpi_is_video_device(struct acpi_device *device)
78{
79 acpi_handle h_dummy;
80 long video_caps = 0;
81
82 if (!device)
83 return 0;
84
85 /* Is this device able to support video switching ? */
86 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) ||
87 ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
88 video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
89
90 /* Is this device able to retrieve a video ROM ? */
91 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
92 video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
93
94 /* Is this device able to configure which video head to be POSTed ? */
95 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
96 ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
97 ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
98 video_caps |= ACPI_VIDEO_DEVICE_POSTING;
99
100 /* Only check for backlight functionality if one of the above hit. */
101 if (video_caps)
102 acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
103 ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
104 &video_caps, NULL);
105
106 return video_caps;
107}
108EXPORT_SYMBOL(acpi_is_video_device);
109
110static acpi_status
111find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
112{
113 long *cap = context;
114 struct pci_dev *dev;
115 struct acpi_device *acpi_dev;
116
117 const struct acpi_device_id video_ids[] = {
118 {ACPI_VIDEO_HID, 0},
119 {"", 0},
120 };
121 if (acpi_bus_get_device(handle, &acpi_dev))
122 return AE_OK;
123
124 if (!acpi_match_device_ids(acpi_dev, video_ids)) {
125 dev = acpi_get_pci_dev(handle);
126 if (!dev)
127 return AE_OK;
128 pci_dev_put(dev);
129 *cap |= acpi_is_video_device(acpi_dev);
130 }
131 return AE_OK;
132}
133
134/*
135 * Returns the video capabilities of a specific ACPI graphics device
136 *
137 * if NULL is passed as argument all ACPI devices are enumerated and
138 * all graphics capabilities of physically present devices are
139 * summarized and returned. This is cached and done only once.
140 */
141long acpi_video_get_capabilities(acpi_handle graphics_handle)
142{
143 long caps = 0;
144 struct acpi_device *tmp_dev;
145 acpi_status status;
146
147 if (acpi_video_caps_checked && graphics_handle == NULL)
148 return acpi_video_support;
149
150 if (!graphics_handle) {
151 /* Only do the global walk through all graphics devices once */
152 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
153 ACPI_UINT32_MAX, find_video, NULL,
154 &caps, NULL);
155 /* There might be boot param flags set already... */
156 acpi_video_support |= caps;
157 acpi_video_caps_checked = 1;
158 /* Add blacklists here. Be careful to use the right *DMI* bits
159 * to still be able to override logic via boot params, e.g.:
160 *
161 * if (dmi_name_in_vendors("XY")) {
162 * acpi_video_support |=
163 * ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
164 *}
165 */
166 } else {
167 status = acpi_bus_get_device(graphics_handle, &tmp_dev);
168 if (ACPI_FAILURE(status)) {
169 ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
170 return 0;
171 }
172 acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
173 ACPI_UINT32_MAX, find_video, NULL,
174 &caps, NULL);
175 }
176 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
177 graphics_handle ? caps : acpi_video_support,
178 graphics_handle ? "on device " : "in general",
179 graphics_handle ? acpi_device_bid(tmp_dev) : ""));
180 return caps;
181}
182EXPORT_SYMBOL(acpi_video_get_capabilities);
183
184/* Returns true if video.ko can do backlight switching */
185int acpi_video_backlight_support(void)
186{
187 /*
188 * We must check whether the ACPI graphics device is physically plugged
189 * in. Therefore this must be called after binding PCI and ACPI devices
190 */
191 if (!acpi_video_caps_checked)
192 acpi_video_get_capabilities(NULL);
193
194 /* First check for boot param -> highest prio */
195 if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
196 return 0;
197 else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
198 return 1;
199
200 /* Then check for DMI blacklist -> second highest prio */
201 if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
202 return 0;
203 else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
204 return 1;
205
206 /* Then go the default way */
207 return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
208}
209EXPORT_SYMBOL(acpi_video_backlight_support);
210
211/*
212 * Use acpi_backlight=vendor/video to force that backlight switching
213 * is processed by vendor specific acpi drivers or video.ko driver.
214 */
215static int __init acpi_backlight(char *str)
216{
217 if (str == NULL || *str == '\0')
218 return 1;
219 else {
220 if (!strcmp("vendor", str))
221 acpi_video_support |=
222 ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
223 if (!strcmp("video", str))
224 acpi_video_support |=
225 ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
226 }
227 return 1;
228}
229__setup("acpi_backlight=", acpi_backlight);
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
38ACPI_MODULE_NAME("video");
39#define _COMPONENT ACPI_VIDEO_COMPONENT
40
41void acpi_video_unregister_backlight(void);
42
43static bool backlight_notifier_registered;
44static struct notifier_block backlight_nb;
45static struct work_struct backlight_notify_work;
46
47static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
48static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
49
50static void acpi_video_parse_cmdline(void)
51{
52 if (!strcmp("vendor", acpi_video_backlight_string))
53 acpi_backlight_cmdline = acpi_backlight_vendor;
54 if (!strcmp("video", acpi_video_backlight_string))
55 acpi_backlight_cmdline = acpi_backlight_video;
56 if (!strcmp("native", acpi_video_backlight_string))
57 acpi_backlight_cmdline = acpi_backlight_native;
58 if (!strcmp("none", acpi_video_backlight_string))
59 acpi_backlight_cmdline = acpi_backlight_none;
60}
61
62static acpi_status
63find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
64{
65 long *cap = context;
66 struct pci_dev *dev;
67 struct acpi_device *acpi_dev;
68
69 static const struct acpi_device_id video_ids[] = {
70 {ACPI_VIDEO_HID, 0},
71 {"", 0},
72 };
73 if (acpi_bus_get_device(handle, &acpi_dev))
74 return AE_OK;
75
76 if (!acpi_match_device_ids(acpi_dev, video_ids)) {
77 dev = acpi_get_pci_dev(handle);
78 if (!dev)
79 return AE_OK;
80 pci_dev_put(dev);
81 *cap |= acpi_is_video_device(handle);
82 }
83 return AE_OK;
84}
85
86/* Force to use vendor driver when the ACPI device is known to be
87 * buggy */
88static int video_detect_force_vendor(const struct dmi_system_id *d)
89{
90 acpi_backlight_dmi = acpi_backlight_vendor;
91 return 0;
92}
93
94static int video_detect_force_video(const struct dmi_system_id *d)
95{
96 acpi_backlight_dmi = acpi_backlight_video;
97 return 0;
98}
99
100static int video_detect_force_native(const struct dmi_system_id *d)
101{
102 acpi_backlight_dmi = acpi_backlight_native;
103 return 0;
104}
105
106static const struct dmi_system_id video_detect_dmi_table[] = {
107 /* On Samsung X360, the BIOS will set a flag (VDRV) if generic
108 * ACPI backlight device is used. This flag will definitively break
109 * the backlight interface (even the vendor interface) untill next
110 * reboot. It's why we should prevent video.ko from being used here
111 * and we can't rely on a later call to acpi_video_unregister().
112 */
113 {
114 .callback = video_detect_force_vendor,
115 .ident = "X360",
116 .matches = {
117 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
118 DMI_MATCH(DMI_PRODUCT_NAME, "X360"),
119 DMI_MATCH(DMI_BOARD_NAME, "X360"),
120 },
121 },
122 {
123 .callback = video_detect_force_vendor,
124 .ident = "Asus UL30VT",
125 .matches = {
126 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
127 DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
128 },
129 },
130 {
131 .callback = video_detect_force_vendor,
132 .ident = "Asus UL30A",
133 .matches = {
134 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
135 DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
136 },
137 },
138
139 /*
140 * These models have a working acpi_video backlight control, and using
141 * native backlight causes a regression where backlight does not work
142 * when userspace is not handling brightness key events. Disable
143 * native_backlight on these to fix this:
144 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
145 */
146 {
147 .callback = video_detect_force_video,
148 .ident = "ThinkPad T420",
149 .matches = {
150 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
151 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
152 },
153 },
154 {
155 .callback = video_detect_force_video,
156 .ident = "ThinkPad T520",
157 .matches = {
158 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
159 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
160 },
161 },
162 {
163 .callback = video_detect_force_video,
164 .ident = "ThinkPad X201s",
165 .matches = {
166 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
167 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
168 },
169 },
170
171 /* The native backlight controls do not work on some older machines */
172 {
173 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
174 .callback = video_detect_force_video,
175 .ident = "HP ENVY 15 Notebook",
176 .matches = {
177 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
178 DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
179 },
180 },
181 {
182 .callback = video_detect_force_video,
183 .ident = "SAMSUNG 870Z5E/880Z5E/680Z5E",
184 .matches = {
185 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
186 DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
187 },
188 },
189 {
190 .callback = video_detect_force_video,
191 .ident = "SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V",
192 .matches = {
193 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
194 DMI_MATCH(DMI_PRODUCT_NAME,
195 "370R4E/370R4V/370R5E/3570RE/370R5V"),
196 },
197 },
198 {
199 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
200 .callback = video_detect_force_video,
201 .ident = "SAMSUNG 3570R/370R/470R/450R/510R/4450RV",
202 .matches = {
203 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
204 DMI_MATCH(DMI_PRODUCT_NAME,
205 "3570R/370R/470R/450R/510R/4450RV"),
206 },
207 },
208 {
209 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
210 .callback = video_detect_force_video,
211 .ident = "SAMSUNG 730U3E/740U3E",
212 .matches = {
213 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
214 DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
215 },
216 },
217 {
218 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
219 .callback = video_detect_force_video,
220 .ident = "SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D",
221 .matches = {
222 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
223 DMI_MATCH(DMI_PRODUCT_NAME,
224 "900X3C/900X3D/900X3E/900X4C/900X4D"),
225 },
226 },
227 {
228 /* https://bugzilla.redhat.com/show_bug.cgi?id=1272633 */
229 .callback = video_detect_force_video,
230 .ident = "Dell XPS14 L421X",
231 .matches = {
232 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
233 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
234 },
235 },
236 {
237 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
238 .callback = video_detect_force_video,
239 .ident = "Dell XPS15 L521X",
240 .matches = {
241 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
242 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
243 },
244 },
245 {
246 /* https://bugzilla.kernel.org/show_bug.cgi?id=108971 */
247 .callback = video_detect_force_video,
248 .ident = "SAMSUNG 530U4E/540U4E",
249 .matches = {
250 DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
251 DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
252 },
253 },
254
255 /* Non win8 machines which need native backlight nevertheless */
256 {
257 /* https://bugzilla.redhat.com/show_bug.cgi?id=1201530 */
258 .callback = video_detect_force_native,
259 .ident = "Lenovo Ideapad S405",
260 .matches = {
261 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
262 DMI_MATCH(DMI_BOARD_NAME, "Lenovo IdeaPad S405"),
263 },
264 },
265 {
266 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
267 .callback = video_detect_force_native,
268 .ident = "Lenovo Ideapad Z570",
269 .matches = {
270 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
271 DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
272 },
273 },
274 {
275 /* https://bugzilla.redhat.com/show_bug.cgi?id=1217249 */
276 .callback = video_detect_force_native,
277 .ident = "Apple MacBook Pro 12,1",
278 .matches = {
279 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
280 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro12,1"),
281 },
282 },
283 {
284 .callback = video_detect_force_native,
285 .ident = "Dell Vostro V131",
286 .matches = {
287 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
288 DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
289 },
290 },
291 { },
292};
293
294/* This uses a workqueue to avoid various locking ordering issues */
295static void acpi_video_backlight_notify_work(struct work_struct *work)
296{
297 if (acpi_video_get_backlight_type() != acpi_backlight_video)
298 acpi_video_unregister_backlight();
299}
300
301static int acpi_video_backlight_notify(struct notifier_block *nb,
302 unsigned long val, void *bd)
303{
304 struct backlight_device *backlight = bd;
305
306 /* A raw bl registering may change video -> native */
307 if (backlight->props.type == BACKLIGHT_RAW &&
308 val == BACKLIGHT_REGISTERED)
309 schedule_work(&backlight_notify_work);
310
311 return NOTIFY_OK;
312}
313
314/*
315 * Determine which type of backlight interface to use on this system,
316 * First check cmdline, then dmi quirks, then do autodetect.
317 *
318 * The autodetect order is:
319 * 1) Is the acpi-video backlight interface supported ->
320 * no, use a vendor interface
321 * 2) Is this a win8 "ready" BIOS and do we have a native interface ->
322 * yes, use a native interface
323 * 3) Else use the acpi-video interface
324 *
325 * Arguably the native on win8 check should be done first, but that would
326 * be a behavior change, which may causes issues.
327 */
328enum acpi_backlight_type acpi_video_get_backlight_type(void)
329{
330 static DEFINE_MUTEX(init_mutex);
331 static bool init_done;
332 static long video_caps;
333
334 /* Parse cmdline, dmi and acpi only once */
335 mutex_lock(&init_mutex);
336 if (!init_done) {
337 acpi_video_parse_cmdline();
338 dmi_check_system(video_detect_dmi_table);
339 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
340 ACPI_UINT32_MAX, find_video, NULL,
341 &video_caps, NULL);
342 INIT_WORK(&backlight_notify_work,
343 acpi_video_backlight_notify_work);
344 backlight_nb.notifier_call = acpi_video_backlight_notify;
345 backlight_nb.priority = 0;
346 if (backlight_register_notifier(&backlight_nb) == 0)
347 backlight_notifier_registered = true;
348 init_done = true;
349 }
350 mutex_unlock(&init_mutex);
351
352 if (acpi_backlight_cmdline != acpi_backlight_undef)
353 return acpi_backlight_cmdline;
354
355 if (acpi_backlight_dmi != acpi_backlight_undef)
356 return acpi_backlight_dmi;
357
358 if (!(video_caps & ACPI_VIDEO_BACKLIGHT))
359 return acpi_backlight_vendor;
360
361 if (acpi_osi_is_win8() && backlight_device_registered(BACKLIGHT_RAW))
362 return acpi_backlight_native;
363
364 return acpi_backlight_video;
365}
366EXPORT_SYMBOL(acpi_video_get_backlight_type);
367
368/*
369 * Set the preferred backlight interface type based on DMI info.
370 * This function allows DMI blacklists to be implemented by external
371 * platform drivers instead of putting a big blacklist in video_detect.c
372 */
373void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
374{
375 acpi_backlight_dmi = type;
376 /* Remove acpi-video backlight interface if it is no longer desired */
377 if (acpi_video_get_backlight_type() != acpi_backlight_video)
378 acpi_video_unregister_backlight();
379}
380EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);
381
382void __exit acpi_video_detect_exit(void)
383{
384 if (backlight_notifier_registered)
385 backlight_unregister_notifier(&backlight_nb);
386}