On Friday, July 05, 2013 02:20:14 PM Rafael J. Wysocki wrote: > On Sunday, June 09, 2013 07:01:39 PM Matthew Garrett wrote: > > Windows 8 leaves backlight control up to individual graphics drivers rather > > than making ACPI calls itself. There's plenty of evidence to suggest that > > the Intel driver for Windows doesn't use the ACPI interface, including the > > fact that it's broken on a bunch of machines when the OS claims to support > > Windows 8. The simplest thing to do appears to be to disable the ACPI > > backlight interface on these systems. > > > > Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/i915_dma.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > > index 3b315ba..23b6292 100644 > > --- a/drivers/gpu/drm/i915/i915_dma.c > > +++ b/drivers/gpu/drm/i915/i915_dma.c > > @@ -1661,6 +1661,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > > /* Must be done after probing outputs */ > > intel_opregion_init(dev); > > acpi_video_register(); > > + /* Don't use ACPI backlight functions on Windows 8 platforms */ > > + if (acpi_osi_version() >= ACPI_OSI_WIN_8) > > + acpi_video_backlight_unregister(); > > } > > > > if (IS_GEN5(dev)) > > > > Well, this causes build failures to happen when the ACPI video driver is > modular and the graphics driver is not. > > I'm not sure how to resolve that, so suggestions are welcome. Actually, that happened with the radeon patch. That said, ACPI_OSI_WIN_8 doesn't make much sense for !CONFIG_ACPI, for example. What about making acpi_video_register() do the quirk instead? We could add an argument to it indicating whether or not quirks should be applied. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
