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

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Date:   Mon, 15 May 2017 15:05:31 +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 11:37 AM, Benjamin Tissoires
> <benjamin.tissoires@...hat.com> wrote:
> > 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.
> 
> OK
> 
> Yeah, that sucks.
> 
> So without the Lv's patch the behavior (on the systems in question) is
> as expected, right?
> 

Yes, reverting these 2 patches restores the pre v4.11 kernel behavior.

Cheers,
Benjamin