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_physical_pci_device() 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 (or display output) 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 and display output
30 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
31 * this file will not be compiled, acpi_video_get_capabilities() and
32 * acpi_video_backlight_support() will always return 0 and vendor specific
33 * drivers always can handle backlight.
37 #include <linux/acpi.h>
38 #include <linux/dmi.h>
40 ACPI_MODULE_NAME("video");
41 #define _COMPONENT ACPI_VIDEO_COMPONENT
43 static long acpi_video_support;
44 static bool acpi_video_caps_checked;
47 acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
53 if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
54 ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
55 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
57 *cap |= ACPI_VIDEO_BACKLIGHT;
58 if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
59 printk(KERN_WARNING FW_BUG PREFIX "ACPI brightness "
60 "control misses _BQC function\n");
61 /* We have backlight support, no need to scan further */
62 return AE_CTRL_TERMINATE;
67 /* Returns true if the device is a video device which can be handled by
69 * The device will get a Linux specific CID added in scan.c to
70 * identify the device as an ACPI graphics device
71 * Be aware that the graphics device may not be physically present
72 * Use acpi_video_get_capabilities() to detect general ACPI video
73 * capabilities of present cards
75 long acpi_is_video_device(struct acpi_device *device)
83 /* Does this device able to support video switching ? */
84 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) &&
85 ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
86 video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
88 /* Does this device able to retrieve a video ROM ? */
89 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
90 video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
92 /* Does this device able to configure which video head to be POSTed ? */
93 if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
94 ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
95 ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
96 video_caps |= ACPI_VIDEO_DEVICE_POSTING;
98 /* Only check for backlight functionality if one of the above hit. */
100 acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
101 ACPI_UINT32_MAX, acpi_backlight_cap_match,
106 EXPORT_SYMBOL(acpi_is_video_device);
109 find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
113 struct acpi_device *acpi_dev;
115 const struct acpi_device_id video_ids[] = {
119 if (acpi_bus_get_device(handle, &acpi_dev))
122 if (!acpi_match_device_ids(acpi_dev, video_ids)) {
123 dev = acpi_get_physical_pci_device(handle);
127 *cap |= acpi_is_video_device(acpi_dev);
133 * Returns the video capabilities of a specific ACPI graphics device
135 * if NULL is passed as argument all ACPI devices are enumerated and
136 * all graphics capabilities of physically present devices are
137 * summerized and returned. This is cached and done only once.
139 long acpi_video_get_capabilities(acpi_handle graphics_handle)
142 struct acpi_device *tmp_dev;
145 if (acpi_video_caps_checked && graphics_handle == NULL)
146 return acpi_video_support;
148 if (!graphics_handle) {
149 /* Only do the global walk through all graphics devices once */
150 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
151 ACPI_UINT32_MAX, find_video,
153 /* There might be boot param flags set already... */
154 acpi_video_support |= caps;
155 acpi_video_caps_checked = 1;
156 /* Add blacklists here. Be careful to use the right *DMI* bits
157 * to still be able to override logic via boot params, e.g.:
159 * if (dmi_name_in_vendors("XY")) {
160 * acpi_video_support |=
161 * ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR;
162 * acpi_video_support |=
163 * ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
167 status = acpi_bus_get_device(graphics_handle, &tmp_dev);
168 if (ACPI_FAILURE(status)) {
169 ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
172 acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
173 ACPI_UINT32_MAX, find_video,
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) : ""));
182 EXPORT_SYMBOL(acpi_video_get_capabilities);
184 /* Returns true if video.ko can do backlight switching */
185 int acpi_video_backlight_support(void)
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
191 if (!acpi_video_caps_checked)
192 acpi_video_get_capabilities(NULL);
194 /* First check for boot param -> highest prio */
195 if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
197 else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
200 /* Then check for DMI blacklist -> second highest prio */
201 if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
203 else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
206 /* Then go the default way */
207 return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
209 EXPORT_SYMBOL(acpi_video_backlight_support);
212 * Returns true if video.ko can do display output switching.
213 * This does not work well/at all with binary graphics drivers
214 * which disable system io ranges and do it on their own.
216 int acpi_video_display_switch_support(void)
218 if (!acpi_video_caps_checked)
219 acpi_video_get_capabilities(NULL);
221 if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VENDOR)
223 else if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO)
226 if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR)
228 else if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VIDEO)
231 return acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING;
233 EXPORT_SYMBOL(acpi_video_display_switch_support);
236 * Use acpi_display_output=vendor/video or acpi_backlight=vendor/video
237 * To force that backlight or display output switching is processed by vendor
238 * specific acpi drivers or video.ko driver.
240 static int __init acpi_backlight(char *str)
242 if (str == NULL || *str == '\0')
245 if (!strcmp("vendor", str))
246 acpi_video_support |=
247 ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
248 if (!strcmp("video", str))
249 acpi_video_support |=
250 ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
254 __setup("acpi_backlight=", acpi_backlight);
256 static int __init acpi_display_output(char *str)
258 if (str == NULL || *str == '\0')
261 if (!strcmp("vendor", str))
262 acpi_video_support |=
263 ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VENDOR;
264 if (!strcmp("video", str))
265 acpi_video_support |=
266 ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
270 __setup("acpi_display_output=", acpi_display_output);