linux-kernel - Re: Keyboard regression by intel-vbtn

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Date:   Wed, 30 Sep 2020 15:28:23 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Limonciello, Mario" <Mario.Limonciello@...l.com>,
        Barnabás Pőcze <pobrn@...tonmail.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.de>
Subject: Re: Keyboard regression by intel-vbtn

Hi,

On 9/29/20 10:47 PM, Limonciello, Mario wrote:
>>
>> I requested on the Ubuntu bug for someone to provide these.
>>
> 
> Joe Barnett was kind enough to share two ACPI dumps to compare.
> Not affected:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1822394/+attachment/5415318/+files/1.2.0.acpidump
> 
> Affected:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1822394/+attachment/5415405/+files/1.13.0.acpidump

Thank you, I took a look at these (before completing my allow-list fix),
but there is not really much which stands out. The only related thing which
stands out is that the 1.13.0 dsdt.dsl has this new bit:

                             Case (0x08)
                             {
                                 Return (^^PCI0.LPCB.H_EC.VGBI.VGBS ())
                             }

Inside the _DSM of the HIDD / INT33D5 device.

             Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
             {
                 If ((Arg0 == ToUUID ("eeec56b3-4442-408f-a792-4edd4d758054")))

What is interesting here is that the PCI0.LPCB.H_EC.VGBI.VGBS object/method
does not actually exist the correct path is:

^^PCI0.LPCB.ECDV.VGBI.VGBS

So this does suggest that something around the VGBS handling changed
(and since it points to a non existing ACPI object, possibly broke)
in the newer BIOS version. But what exactly is going on on this XPS 2-in-1
cannot really be derived from the acpidumps.

Regards,

Hans