Re: [PATCH] ACPI / blacklist: blacklist Win8 OSI for Dell Inspiron 7437

[Matthew Garrett <mjg59@srcf.ucam.org>]

With Windows 8 enabled you're going down this path:

        If (_OSI (WIN8))
        {
            Local0 = 0x81
        }

With it blacklisted, you're going down this path:

        If (_OSI (WIN7))
        {
            Local0 = 0x80
            Local1 = _REV /* \_REV */
            If ((Local1 == 0x05))
            {
                Local0 = 0x40
            }
        }

So your guess about _REV was actually correct - if the OS claims to be 
Windows 7 and returns 5 to _REV, it'll let Local0 to 0x40. This results 
in:

        If ((Local0 == 0x40))
        {
            MIS0 = SMI (0x98, Zero)
            MIS0 &= 0x13
        }

MIS0 appears to be involved in various event delivery paths, so my 
suspicion is that the firmware is deliberately working around a quirk of 
Linux behaviour in order to deliver events appropriately. If so, your 
patch won't help in 4.1 because _REV now returns 2, and so we need to 
root cause the actual problem and fix that instead.

-- 
Matthew Garrett | mjg59@srcf.ucam.org