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

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Date:   Thu, 01 Jun 2017 23:43:54 +0200
From:   Bastien Nocera <hadess@...ess.net>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        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>
Cc:     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 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.

Cheers