Re: [PATCH 4/5] platform/x86: intel-vbtn: Also handle tablet-mode switch on "Detachable" and "Portable" chassis-types

[Hans de Goede]

Hi,

On 5/5/20 4:27 PM, Andy Shevchenko wrote:
> On Tue, May 5, 2020 at 5:22 PM <Mario.Limonciello@xxxxxxxx> wrote:
> > > -----Original Message-----
> > > From: platform-driver-x86-owner@xxxxxxxxxxxxxxx <platform-driver-x86-
> > > owner@xxxxxxxxxxxxxxx> On Behalf Of Hans de Goede
> > > Sent: Tuesday, May 5, 2020 4:06 AM
> > > To: Limonciello, Mario; dvhart@xxxxxxxxxxxxx; andy@xxxxxxxxxxxxx
> > > Cc: linux-acpi@xxxxxxxxxxxxxxx; platform-driver-x86@xxxxxxxxxxxxxxx; linux-
> > > kernel@xxxxxxxxxxxxxxx
> > > Subject: Re: [PATCH 4/5] platform/x86: intel-vbtn: Also handle tablet-mode
> > > switch on "Detachable" and "Portable" chassis-types
> > >
> > >
> > > [EXTERNAL EMAIL]
> > >
> > > Hi,
> > >
> > > On 5/4/20 5:37 PM, Mario.Limonciello@xxxxxxxx wrote:
> > > > > -----Original Message-----
> > > > > From: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > > > Sent: Saturday, May 2, 2020 1:30 PM
> > > > > To: Darren Hart; Andy Shevchenko; Limonciello, Mario
> > > > > Cc: Hans de Goede; linux-acpi@xxxxxxxxxxxxxxx; platform-driver-
> > > > > x86@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > > > Subject: [PATCH 4/5] platform/x86: intel-vbtn: Also handle tablet-mode
> > > switch
> > > > > on "Detachable" and "Portable" chassis-types
> > > > >
> > > > >
> > > > > [EXTERNAL EMAIL]
> > > > >
> > > > > Commit de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode
> > > > > switch on 2-in-1's") added a DMI chassis-type check to avoid accidentally
> > > > > reporting SW_TABLET_MODE = 1 to userspace on laptops.
> > > > >
> > > > > Some devices with a detachable keyboard and using the intel-vbnt (INT33D6)
> > > > > interface to report if they are in tablet mode (keyboard detached) or not,
> > > > > report 32 / "Detachable" as chassis-type, e.g. the HP Pavilion X2 series.
> > > > >
> > > > > Other devices with a detachable keyboard and using the intel-vbnt (INT33D6)
> > > > > interface to report SW_TABLET_MODE, report 8 / "Portable" as chassis-type.
> > > > > The Dell Venue 11 Pro 7130 is an example of this.
> > > > >
> > > > > Extend the DMI chassis-type check to also accept Portables and Detachables
> > > > > so that the intel-vbtn driver will report SW_TABLET_MODE on these devices.
> > > > >
> > > > > Note the chassis-type check was originally added to avoid a false-positive
> > > > > tablet-mode report on the Dell XPS 9360 laptop. To the best of my knowledge
> > > > > that laptop is using a chassis-type of 9 / "Laptop", so after this commit
> > > > > we still ignore the tablet-switch for that chassis-type.
> > > >
> > > > Yes that's correct.
> > > >
> > > > > Fixes: de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode
> > > > > switch on 2-in-1's")
> > > > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > > > ---
> > > > > Looking at the Microsoft Windows documentation for tablet-mode reporting:
> > > > > https://docs.microsoft.com/en-us/windows-hardware/drivers/gpiobtn/button-
> > > > > implementation
> > > > >
> > > > > Then the presence of a tablet-mode switch is indicated by the presence
> > > > > of a PNP0C60 compatible ACPI devices. There are 2 ways in which this device
> > > > > can report the tablet-mode. 1. Directly providing a GpioInt resource inside
> > > > > the PNP0C60 device, 2. Through injecting events from a Windows driver.
> > > > >
> > > > > It seems that the intel-vbtn / the INT33D6 ACPI device is the ACPI side
> > > > > of Intel's generic solution for the case where the tablet-mode comes from
> > > > > the embedded-controller and needs to be "injected".
> > > > >
> > > > > This all suggests that it might be better to replace the chassis-type
> > > > > check with a acpi_dev_present("PNP0C60", NULL, -1) check.
> > > > >
> > > > > Mario, can you provide an acpidump and alsa-info.sh output for the
> > > > > Dell XPS 9360, so that I can check if that might help with the issue
> > > > > there, and thus is a potential candidate to replace the chassis-type
> > > > > check?
> > > >
> > > > Unfortunately with WFH right now, I don't have access to a XPS 9630 to
> > > > double check the patch series.
> > > >
> > > > However I do agree this should be a good approach.
> > >
> > > Ok, so lets stick with the chassis-type check (as amended by this patch)
> > > for now then. Then once you are able to go to your office again, we
> > > can examine the acpi_dev_present("PNP0C60", NULL, -1) alternative.
> >
> > I know XPS 13's are pretty popular, perhaps someone on the mailing list who has
> > one can share ACPI dump in the interim.
>
> https://github.com/intel/dptfxtract/issues/13

Good one.

So this has:

        Device (CIND)
        {
            Name (_HID, "INT33D3" /* Intel GPIO Buttons */)  // _HID: Hardware I
            Name (_CID, "PNP0C60" /* Display Sensor Device */)  // _CID: Compati
            Method (_STA, 0, Serialized)  // _STA: Status
            {
                If ((OSYS >= 0x07DC))
                {
                    Return (0x0F)
                }

                Return (Zero)
            }
        }

And OSYS >= 0x07DC checks for "Windows 2012" which Linux does advertise,
so despite not having a tablet-mode(switch) the XPS 9360 still has a
PNP0C60 ACPI device and will report 0xf (present) as status for it,
so a acpi_dev_present("PNP0C60", NULL, -1) check will succeed on it.

Conclusion: such a check is not a valid alternative for checking DMI
chassis-types (and from that pov this series thus is ready for merging).

Regards,

Hans