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8e5c2b776a
We attempted to address a regression introduced by commita57f7f9(ACPICA: Add Windows8/Server2012 string for _OSI method.) after which ACPI video backlight support doesn't work on a number of systems, because the relevant AML methods in the ACPI tables in their BIOSes become useless after the BIOS has been told that the OS is compatible with Windows 8. That problem is tracked by the bug entry at: https://bugzilla.kernel.org/show_bug.cgi?id=51231 Commit8c5bd7a(ACPI / video / i915: No ACPI backlight if firmware expects Windows 8) introduced for this purpose essentially prevented the ACPI backlight support from being used if the BIOS had been told that the OS was compatible with Windows 8 and the i915 driver was loaded, in which case the backlight would always be handled by i915. Unfortunately, however, that turned out to cause problems with backlight to appear on multiple systems with symptoms indicating that i915 was unable to control the backlight on those systems as expected. For this reason, revert commit8c5bd7a, but leave the function acpi_video_backlight_quirks() introduced by it, because another commit on top of it uses that function. References: https://lkml.org/lkml/2013/7/21/119 References: https://lkml.org/lkml/2013/7/22/261 References: https://lkml.org/lkml/2013/7/23/429 References: https://lkml.org/lkml/2013/7/23/459 References: https://lkml.org/lkml/2013/7/23/81 References: https://lkml.org/lkml/2013/7/24/27 Reported-and-tested-by: James Hogan <james@albanarts.com> Reported-and-tested-by: Kamal Mostafa <kamal@canonical.com> Reported-and-tested-by: Jörg Otte <jrg.otte@gmail.com> Reported-and-tested-by: Steven Newbury <steve@snewbury.org.uk> Reported-by: Martin Steigerwald <Martin@lichtvoll.de> Reported-by: Kalle Valo <kvalo@adurom.com> Tested-by: Joerg Platte <jplatte@naasa.net> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
35 lines
958 B
C
35 lines
958 B
C
#ifndef __ACPI_VIDEO_H
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#define __ACPI_VIDEO_H
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#include <linux/errno.h> /* for ENODEV */
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struct acpi_device;
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#define ACPI_VIDEO_CLASS "video"
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#define ACPI_VIDEO_DISPLAY_CRT 1
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#define ACPI_VIDEO_DISPLAY_TV 2
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#define ACPI_VIDEO_DISPLAY_DVI 3
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#define ACPI_VIDEO_DISPLAY_LCD 4
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#define ACPI_VIDEO_DISPLAY_LEGACY_MONITOR 0x0100
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#define ACPI_VIDEO_DISPLAY_LEGACY_PANEL 0x0110
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#define ACPI_VIDEO_DISPLAY_LEGACY_TV 0x0200
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#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
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extern int acpi_video_register(void);
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extern void acpi_video_unregister(void);
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extern int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid);
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#else
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static inline int acpi_video_register(void) { return 0; }
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static inline void acpi_video_unregister(void) { return; }
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static inline int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid)
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{
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return -ENODEV;
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}
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#endif
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#endif
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