On Friday, July 05, 2013 10:00:55 PM Rafael J. Wysocki wrote: > 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 at nebula.com> > > > --- > > > 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. Actually, I wonder what about the appended patch (on top of the Aaron's https://patchwork.kernel.org/patch/2812951/) instead of [1-3/3] from this series. Thanks, Rafael --- drivers/acpi/video_detect.c | 11 +++++++++-- include/linux/acpi.h | 1 + 2 files changed, 10 insertions(+), 2 deletions(-) Index: linux-pm/drivers/acpi/video_detect.c =================================================================== --- linux-pm.orig/drivers/acpi/video_detect.c +++ linux-pm/drivers/acpi/video_detect.c @@ -203,6 +203,9 @@ long acpi_video_get_capabilities(acpi_ha */ dmi_check_system(video_detect_dmi_table); + + if (acpi_gbl_osi_data >= ACPI_OSI_WIN_8) + acpi_video_support |= ACPI_VIDEO_FORCE_NO_BACKLIGHT; } else { status = acpi_bus_get_device(graphics_handle, &tmp_dev); if (ACPI_FAILURE(status)) { @@ -258,13 +261,17 @@ int acpi_video_backlight_support(void) { acpi_video_caps_check(); - /* First check for boot param -> highest prio */ + /* First, check if no backlight support has been forced upon us. */ + if (acpi_video_support & ACPI_VIDEO_FORCE_NO_BACKLIGHT) + return 0; + + /* Next check for boot param -> second highest prio */ if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR) return 0; else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO) return 1; - /* Then check for DMI blacklist -> second highest prio */ + /* Then check for DMI blacklist -> third highest prio */ if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR) return 0; else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO) Index: linux-pm/include/linux/acpi.h =================================================================== --- linux-pm.orig/include/linux/acpi.h +++ linux-pm/include/linux/acpi.h @@ -191,6 +191,7 @@ extern bool wmi_has_guid(const char *gui #define ACPI_VIDEO_BACKLIGHT_DMI_VIDEO 0x0200 #define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR 0x0400 #define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VIDEO 0x0800 +#define ACPI_VIDEO_FORCE_NO_BACKLIGHT 0x1000 #if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE)
