linux-kernel - RE: [systemd-devel] [WIP PATCH 0/4] Rework the unreliable LID switch exported by ACPI

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Date:   Tue, 20 Jun 2017 02:45:09 +0000
From:   "Zheng, Lv" <lv.zheng@...el.com>
To:     Bastien Nocera <hadess@...ess.net>
CC:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Peter Hutterer <peter.hutterer@...-t.net>,
        Lennart Poettering <mzxreary@...inter.de>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        "Brown, Len" <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "systemd-devel@...ts.freedesktop.org" 
        <systemd-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>
Subject: RE: [systemd-devel] [WIP PATCH 0/4] Rework the unreliable LID
 switch exported by ACPI

Hi,

> From: Bastien Nocera [mailto:hadess@...ess.net]
> Subject: Re: [systemd-devel] [WIP PATCH 0/4] Rework the unreliable LID switch exported by ACPI
> 
> On Mon, 2017-06-19 at 01:43 +0000, Zheng, Lv wrote:
> > <snip>
> > >
> > > If you implement it in such a way that GNOME settings daemon
> > > behaves weirdly, you'll get my revert
> > > request in the mail. Do. Not. Ever. Lie.
> >
> > First, I don't know what should be reverted...
> > I have 2 solutions here for review, and Benjamin has 1.
> > And none of them has been upstreamed.
> > We are just discussing.
> 
> The discussion is getting tiring quite frankly. We've been over this
> for nearly a year now, and with no end in sight.

We have concerns to introduce too complicated logics to such a
simple button driver especially the logics are related to platform
firmware, input ABI and user space behaviors.

I understand the situation.
Anyway this shouldn't be a big deal.
Let's prepare a smarter series to collect all fixes and solutions
with runtime configurables and get that to the end users.
So that we can figure out which is the simplest solution.

But before that, let me ask several questions about gnome-setting-deamon.

> 
> > However we need to get 1 of them upstreamed in next cycle.
> >
> > I think users won't startup gnome-setting-daemon right after resume.
> > It should have already been started.
> >
> > There is only 1 platform may see delayed state update after resume.
> > Let's see if there is a practical issue.
> > 1. Before suspend, the "lid state" is "close", and
> > 2. After resume, the state might remain "close" for a while
> >    Since libinput won't deliver close to userspace,
> >    and gnome-setting-daemon listens to key switches, there is no
> > wrong behavior.
> 
> It doesn't. It listens to UPower, which tells user-space whether there
> is a lid switch, and whether it's opened or closed.

Thanks for the information.
However I don't see differences here.

> 
> > 3. Then after several seconds, "open" arrives.
> >    gnome-setting-daemon re-arrange monitors and screen layouts in
> > response to the new event.
> 
> Just how is anyone supposed to know that there is an event coming?

Will UPower deliver EV_SW key events to gnome-setting-daemon?

> 
> > So there is no problem. IMO, there is no need to improve for post-
> > resume case.
> >
> > Users will just startup gnome-setting-daemon once after boot.
> > And it's likely that when it is started, the state is correct.
> 
> You cannot rely on when gnome-settings-daemon will be started to make
> *any* decision. Certainly not decisions on how the kernel should
> behave.

My bad wording, I just meant:
When gnome-settings-daemon is started is not related to what we are
discussing.

Do you want to fix regressions?
Or you want to fix new issues on recent platforms?
If you want to fix regressions, I think Benjamin has submitted a revision
to use old method mode, there shouldn't be regressions for
gnome-settings-daemon.

What else we want to do is to fix regressions related to systemd when
we go back to default method mode. Since there is no issue with systemd
233 and after just applying a small change, systemd 229 can also be
worked around, I mean dynamically add/remove input node is not strictly
required for achieving our purposes.

But if you want to fix new issues on new platforms, we can discuss
further and determine which program should be changed and which program
is the best candidate to stop all problems - the ACPI button driver or
the user space.

Cheers
Lv