2 * Copyright (C) 2008 SuSE Linux Products GmbH
3 * Thomas Renninger <trenn@suse.de>
5 * May be copied or modified under the terms of the GNU General Public License
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
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
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();
23 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
24 * are available, video.ko should be used to handle the device.
26 * Otherwise vendor specific drivers like thinkpad_acpi, asus_acpi,
27 * sony_acpi,... can take care about backlight brightness.
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.
36 #include <linux/acpi.h>
37 #include <linux/dmi.h>
38 #include <linux/pci.h>
40 #define PREFIX "ACPI: "
42 ACPI_MODULE_NAME("video");
43 #define _COMPONENT ACPI_VIDEO_COMPONENT
45 static long acpi_video_support
;
46 static bool acpi_video_caps_checked
;
49 acpi_backlight_cap_match(acpi_handle handle
, u32 level
, void *context
,
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 "
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
;
69 /* Returns true if the device is a video device which can be handled by
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
77 long acpi_is_video_device(struct acpi_device
*device
)
85 /* Is this device able to retrieve a video ROM ? */
86 if (ACPI_SUCCESS(acpi_get_handle(device
->handle
, "_ROM", &h_dummy
)))
87 video_caps
|= ACPI_VIDEO_ROM_AVAILABLE
;
89 /* Is this device able to configure which video head to be POSTed ? */
90 if (ACPI_SUCCESS(acpi_get_handle(device
->handle
, "_VPO", &h_dummy
)) &&
91 ACPI_SUCCESS(acpi_get_handle(device
->handle
, "_GPD", &h_dummy
)) &&
92 ACPI_SUCCESS(acpi_get_handle(device
->handle
, "_SPD", &h_dummy
)))
93 video_caps
|= ACPI_VIDEO_DEVICE_POSTING
;
95 /* Only check for backlight functionality if one of the above hit. */
97 acpi_walk_namespace(ACPI_TYPE_DEVICE
, device
->handle
,
98 ACPI_UINT32_MAX
, acpi_backlight_cap_match
, NULL
,
103 EXPORT_SYMBOL(acpi_is_video_device
);
106 find_video(acpi_handle handle
, u32 lvl
, void *context
, void **rv
)
110 struct acpi_device
*acpi_dev
;
112 const struct acpi_device_id video_ids
[] = {
116 if (acpi_bus_get_device(handle
, &acpi_dev
))
119 if (!acpi_match_device_ids(acpi_dev
, video_ids
)) {
120 dev
= acpi_get_pci_dev(handle
);
124 *cap
|= acpi_is_video_device(acpi_dev
);
130 * Returns the video capabilities of a specific ACPI graphics device
132 * if NULL is passed as argument all ACPI devices are enumerated and
133 * all graphics capabilities of physically present devices are
134 * summarized and returned. This is cached and done only once.
136 long acpi_video_get_capabilities(acpi_handle graphics_handle
)
139 struct acpi_device
*tmp_dev
;
142 if (acpi_video_caps_checked
&& graphics_handle
== NULL
)
143 return acpi_video_support
;
145 if (!graphics_handle
) {
146 /* Only do the global walk through all graphics devices once */
147 acpi_walk_namespace(ACPI_TYPE_DEVICE
, ACPI_ROOT_OBJECT
,
148 ACPI_UINT32_MAX
, find_video
, NULL
,
150 /* There might be boot param flags set already... */
151 acpi_video_support
|= caps
;
152 acpi_video_caps_checked
= 1;
153 /* Add blacklists here. Be careful to use the right *DMI* bits
154 * to still be able to override logic via boot params, e.g.:
156 * if (dmi_name_in_vendors("XY")) {
157 * acpi_video_support |=
158 * ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
162 status
= acpi_bus_get_device(graphics_handle
, &tmp_dev
);
163 if (ACPI_FAILURE(status
)) {
164 ACPI_EXCEPTION((AE_INFO
, status
, "Invalid device"));
167 acpi_walk_namespace(ACPI_TYPE_DEVICE
, graphics_handle
,
168 ACPI_UINT32_MAX
, find_video
, NULL
,
171 ACPI_DEBUG_PRINT((ACPI_DB_INFO
, "We have 0x%lX video support %s %s\n",
172 graphics_handle
? caps
: acpi_video_support
,
173 graphics_handle
? "on device " : "in general",
174 graphics_handle
? acpi_device_bid(tmp_dev
) : ""));
177 EXPORT_SYMBOL(acpi_video_get_capabilities
);
179 /* Returns true if video.ko can do backlight switching */
180 int acpi_video_backlight_support(void)
183 * We must check whether the ACPI graphics device is physically plugged
184 * in. Therefore this must be called after binding PCI and ACPI devices
186 if (!acpi_video_caps_checked
)
187 acpi_video_get_capabilities(NULL
);
189 /* First check for boot param -> highest prio */
190 if (acpi_video_support
& ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR
)
192 else if (acpi_video_support
& ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO
)
195 /* Then check for DMI blacklist -> second highest prio */
196 if (acpi_video_support
& ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
)
198 else if (acpi_video_support
& ACPI_VIDEO_BACKLIGHT_DMI_VIDEO
)
201 /* Then go the default way */
202 return acpi_video_support
& ACPI_VIDEO_BACKLIGHT
;
204 EXPORT_SYMBOL(acpi_video_backlight_support
);
207 * Use acpi_backlight=vendor/video to force that backlight switching
208 * is processed by vendor specific acpi drivers or video.ko driver.
210 static int __init
acpi_backlight(char *str
)
212 if (str
== NULL
|| *str
== '\0')
215 if (!strcmp("vendor", str
))
216 acpi_video_support
|=
217 ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR
;
218 if (!strcmp("video", str
))
219 acpi_video_support
|=
220 ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO
;
224 __setup("acpi_backlight=", acpi_backlight
);