linux-kernel - Dell WMI Hotkeys on Dell Inspiron 15R SE (7520)

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Date:   Tue, 1 May 2018 13:00:03 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Michał Kępień <kernel@...pniu.pl>,
        qwrd <mistave@...ntermail.com>
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Dell WMI Hotkeys on Dell Inspiron 15R SE (7520)

Hello!

Mistave contacted me, because he has Dell Inspiron 15R SE (7520) on
which are not working 3 hotkeys located in the right upper corner.

After debugging we find out that this Dell Inspirion sends following WMI
event to dell-wmi.c driver:

=====================================================================

----------------------------------------
Left WMI key: Windows Mobility Center
Press:    Key with type 0x0000 and code 0xe026 pressed
Hold:     -
Release:  -

Only the press event was observed. It does not repeat when held down.

----------------------------------------
Middle WMI key: Dell Audio With Preset Switch
Press:    Key with type 0x0000 and code 0xe02a pressed
Hold:     Key with type 0x0000 and code 0xe02b pressed
          (code 0xe02a also repeats continuously)
Release:  Key with type 0x0000 and code 0xe02c pressed

Code 0xe02a repeats, if button is held down. After about 3 seconds a
single code 0xe02b entry will also appear. When released before the code
0xe02b pops up, the code 0xe02c will appear. If released afterwards,
code 0xe02c does not appear.

----------------------------------------
Right WMI key: Dell Instant Launch
Press:    -
Hold:     Key with type 0x0000 and code 0xe025 pressed
Release:  Key with type 0x0000 and code 0xe024 pressed

Code 0xe024 only appears, if the button is released within about 3
seconds. If held down for longer, a single code 0xe025 will appear. If
released after the code 0xe025 appears, the code 0xe024 will not appear.

=====================================================================

Such hold and release events in 3sec time period are strange and I'm not
sure how we should handle them. Any idea?

Also there is another problem. Driver dell-wmi.c ignores 0xe025 events
because on all other machines it is reported also by PS/2 internal
keyboard. But seems not on this Dell Inspirion. How to handle this fact?
Add a new quirk into dell-wmi.c code?

Mario, do you have a documentation or something which can prove above
observation that keys are really reported via such strange WMI events?

-- 
Pali Rohár
pali.rohar@...il.com

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