http://bugzilla.kernel.org/show_bug.cgi?id=13577
--- Comment #2 from Zhang Rui <rui.zh...@intel.com> 2009-06-24 01:54:24 --- (In reply to comment #0) > When the DSDT detects Windows Vista (which Linux seems to pretend to be), it > disables the WMI method and also disables direct control using the hardware > keys, instead expecting software to react to those keypresses and control it > using the ACPI Video device. > what if you boot with acpi_osi="!Windows 2006"? > > The ACPI Video Interface is broken. There are three devices supported: OVGA, > PEGP.EVGA, and PEGP.NVGA. As far as I can tell, OVGA is supposed to be an > integrated graphics controller that doesn't exist. EVGA and NVGA are very > similar and I don't know which one corresponds to my laptop or how the driver > is supposed to tell between them, but clearly one of them is the correct one > and corresponds to the modular MXM card on the laptop. > > OVGA would work except that it corresponds to a nonexistent PCI device, so > acpi_get_physical_pci_device kills it. Hacking this out makes things work (the > brightness setting is via the EC anyway, and works the same for all three > devices), but that doesn't sound like a good idea. > > EVGA and NVGA fail to register as video devices because they lack the _DOS > method that ACPI specifies as required for backlight functionality. They do > have _DOD, which isn't enough for display output switching support, but at > least identifies them as video devices. They fail the acpi_is_video_device > because that only checks for backlight support if one of the other three > features is fully present. They also fail acpi_video_bus_check because that > again wants one of the three features. > > At this point I'm unsure of what the best way to fix this is. My guess would > be > to make acpi_is_video_device check for brightness controls even if only _DOD > is > present, and also make acpi_video_bus_check consider just _DOD good enough to > pass a device. Then the other issue left would be the duplicated device (the > backlight control is really messed up when it tries to do the same thing to > two > different devices). Applying those two hacks and and manually unbinding one of > the devices from the driver via sysfs makes things work for me. hah, then this is apperantly a BIOS problem to me because _DOS is mandatory according to the ACPI spec. But anyway, we should make it work in Linux. what about this proposal? 1. acpi_is_video_device returns TRUE if only _DOD in found. 2. print a warning message if there is no _DOS method. 3. don't touch _DOS in ACPI video driver if it's not available. patch will be attached later. -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. ------------------------------------------------------------------------------ _______________________________________________ acpi-bugzilla mailing list acpi-bugzilla@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/acpi-bugzilla
