於 五，2013-04-19 於 11:15 +0800，Aaron Lu 提到： > On 04/03/2013 03:04 PM, Ben Jencks wrote: > > On 04/02/2013 09:00 AM, Seth Forshee wrote: > >> On Tue, Apr 02, 2013 at 05:08:23PM +0800, Aaron Lu wrote: > >>> > >>> I really wondered, how Windows handled this, it should have the same > >>> problem, unless they are not using the acpi video interface? > >> > >> I can only guess. > >> > >> I think I remember reading that Windows 8 does smooth backlight > >> transitions, so it may well hit every intermediate brightness value. > >> Lenovo could also be supplying a driver which rounds values to the > >> nearest working value or uses some other interface or something else. > > > > Just checked; Windows 8 doesn't use the ACPI interface. It seems to have > > access to at least 100 distinct brightness levels. > > I just came across a document on win8 backlight control, it has words > like this: > " > In Windows 8, the primary mechanism by which a platform should expose > its display brightness control functionality is the Windows Display > Driver Model (WDDM) miniport Device Driver Interfaces (DDI). > " > So looks like, on win8, ACPI interface is not used for these systems. > > The link for the document is here: > http://msdn.microsoft.com/en-US/library/windows/hardware/jj159305 > > -Aaron > Per WDDM document, OEM/ODM should keep the ACPI methods (_BQL, _BCM, _BQC) available for compliant to the OS that doesn't support WDDM, e.g. XP, Vista. But, I discussed with Acer for this situation at last year, they didn't force their ODM do test ACPI compatibility. They only test through Windows 8 UI with Fn keys. Thanks a lot! Joey Lee -- 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
