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

[Bastien Nocera <hadess@hadess.net>]

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