linux-kernel - Re: [PATCH 2/2] Revert "ACPI / button: Change default behavior to lid_init

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Message-ID: <20170515093752.GB11762@mail.corp.redhat.com>
Date:   Mon, 15 May 2017 11:37:52 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Zheng, Lv" <lv.zheng@...el.com>,
        Jiri Eischmann <jeischma@...hat.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] Revert "ACPI / button: Change default behavior to
 lid_init_state=open"

On May 15 2017 or thereabouts, Rafael J. Wysocki wrote:
> On Mon, May 15, 2017 at 9:45 AM, Benjamin Tissoires
> <benjamin.tissoires@...hat.com> wrote:
> > On May 12 2017 or thereabouts, Rafael J. Wysocki wrote:
> >> On Friday, May 12, 2017 02:36:20 AM Zheng, Lv wrote:
> >> > Hi,
> >> >
> >> > > From: Benjamin Tissoires [mailto:benjamin.tissoires@...hat.com]
> >> > > Subject: Re: [PATCH 2/2] Revert "ACPI / button: Change default behavior to lid_init_state=open"
> >> > >
> >> > > On May 11 2017 or thereabouts, Zheng, Lv wrote:
> >> > > > Hi,
> >> > > >
> >> > > > > From: Benjamin Tissoires [mailto:benjamin.tissoires@...hat.com]
> >> > > > > Subject: [PATCH 2/2] Revert "ACPI / button: Change default behavior to lid_init_state=open"
> >> > > > >
> >> > > > > This reverts commit 77e9a4aa9de10cc1418bf9a892366988802a8025.
> >> > > > >
> >> > > > > Even if the method implementation can be buggy on some platform,
> >> > > > > the "open" choice is worse. It breaks docking stations basically
> >> > > > > and there is no way to have a user-space hwdb to fix that.
> >> > > > >
> >> > > > > On the contrary, it's rather easy in user-space to have a hwdb
> >> > > > > with the problematic platforms. Then, libinput (1.7.0+) can fix
> >> > > > > the state of the LID switch for us: you need to set the udev
> >> > > > > property LIBINPUT_ATTR_LID_SWITCH_RELIABILITY to 'write_open'.
> >> > > > >
> >> > > > > When libinput detects internal keyboard events, it will
> >> > > > > overwrite the state of the switch to open, making it reliable
> >> > > > > again. Given that logind only checks the LID switch value after
> >> > > > > a timeout, we can assume the user will use the internal keyboard
> >> > > > > before this timeout expires.
> >> > > > >
> >> > > > > For example, such a hwdb entry is:
> >> > > > >
> >> > > > > libinput:name:*Lid Switch*:dmi:*svnMicrosoftCorporation:pnSurface3:*
> >> > > > >  LIBINPUT_ATTR_LID_SWITCH_RELIABILITY=write_open
> >> > > >
> >
> > [...]
> >
> >>
> >> Well, if it worked in a specific way that users depended on before the commit in
> >> question and now it works differently, then it does break things.
> >>
> >> Benjamin, my understanding is that this is the case, is it correct?
> >
> > That is correct. This patch I reverted introduces regression for professional
> > laptops that expect the LID switch to be reported accurately.
> 
> And from a user's perspective, what does not work any more?

If you boot or resume your laptop with the lid closed on a docking
station while using an external monitor connected to it, both internal
and external displays will light on, while only the external should.

There is a design choice in gdm to only provide the greater on the
internal display when lit on, so users only see a gray area on the
external monitor. Also, the cursor will not show up as it's by default
on the internal display too.

To "fix" that, users have to open the laptop once and close it once
again to sync the state of the switch with the hardware state.

Cheers,
Benjamin

> 
> Thanks,
> Rafael