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

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Date:   Fri, 2 Jun 2017 09:24:26 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Bastien Nocera <hadess@...ess.net>
Cc:     Lv Zheng <lv.zheng@...el.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
        Peter Hutterer <peter.hutterer@...-t.net>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        systemd-devel@...ts.freedesktop.org, linux-input@...r.kernel.org
Subject: Re: [WIP PATCH 0/4] Rework the unreliable LID switch exported by ACPI

On Jun 01 2017 or thereabouts, Bastien Nocera wrote:
> On Thu, 2017-06-01 at 20:46 +0200, Benjamin Tissoires wrote:
> > Hi,
> > 
> > Sending this as a WIP as it still need a few changes, but it mostly
> > works as
> > expected (still not fully compliant yet).
> > 
> > So this is based on Lennart's comment in [1]: if the LID state is not
> > reliable,
> > the kernel should not export the LID switch device as long as we are
> > not sure
> > about its state.
> > 
> > That is the basic idea, and here are some more general comments:
> > Lv described the 5 cases in "RFC PATCH v3" regarding the LID switch.
> > Let me rewrite them here (they are in patch 2):
> > 
> > 1. Some platforms send "open" ACPI notification to the OS and the
> > event
> >    arrive before the button driver is resumed;
> > 2. Some platforms send "open" ACPI notification to the OS, but the
> > event
> >    arrives after the button driver is resumed, ex., Samsung N210+;
> > 3. Some platforms never send an "open" ACPI notification to the OS,
> > but
> >    update the cached _LID return value to "open", and this update
> > arrives
> >    before the button driver is resumed;
> > 4. Some platforms never send an "open" ACPI notification to the OS,
> > but
> >    update the cached _LID return value to "open", but this update
> > arrives
> >    after the button driver is resumed, ex., Surface Pro 3;
> > 5. Some platforms never send an "open" ACPI notification to the OS,
> > and
> >    _LID ACPI method returns a value which stays to "close", ex.,
> >    Surface Pro 1.
> 
> In which case does the Surface 3 lie? I believe we still needed your
> "gpiolib-acpi: make sure we trigger the events at least once" patch to
> make that one work.

Well, the surface 3 is using a different driver for the LID switch
(surface3-wmi). From what I can remember, we don't need this patch when
using this driver (which is why I did not submitted it further). But I
might be wrong...

Cheers,
Benjamin