From 8e5c2b776ae4c35f54547c017e0a943429f5748a Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 25 Jul 2013 21:43:39 +0200 Subject: Revert "ACPI / video / i915: No ACPI backlight if firmware expects Windows 8" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We attempted to address a regression introduced by commit a57f7f9 (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 Commit 8c5bd7a (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 commit 8c5bd7a, 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 Reported-and-tested-by: Kamal Mostafa Reported-and-tested-by: Jörg Otte Reported-and-tested-by: Steven Newbury Reported-by: Martin Steigerwald Reported-by: Kalle Valo Tested-by: Joerg Platte Signed-off-by: Rafael J. Wysocki --- drivers/gpu/drm/i915/i915_dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/i915_dma.c') diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index cf188ab7051..adb319b53ec 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -1648,7 +1648,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) if (INTEL_INFO(dev)->num_pipes) { /* Must be done after probing outputs */ intel_opregion_init(dev); - acpi_video_register_with_quirks(); + acpi_video_register(); } if (IS_GEN5(dev)) -- cgit v1.2.3-70-g09d2