linux-kernel - RE: [PATCH 3/4] dell-wmi: Add information about other WMI event codes

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Date:	Wed, 22 Jun 2016 14:46:40 +0000
From:	<Mario_Limonciello@...l.com>
To:	<gabriele.mzt@...il.com>, <pali.rohar@...il.com>
CC:	<mjg59@...f.ucam.org>, <dvhart@...radead.org>, <kernel@...pniu.pl>,
	<luto@...nel.org>, <alex.hung@...onical.com>,
	<platform-driver-x86@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 3/4] dell-wmi: Add information about other WMI event codes

> -----Original Message-----
> From: Gabriele Mazzotta [mailto:gabriele.mzt@...il.com]
> Sent: Wednesday, June 22, 2016 9:40 AM
> To: Limonciello, Mario <Mario_Limonciello@...l.com>; pali.rohar@...il.com
> Cc: mjg59@...f.ucam.org; dvhart@...radead.org; kernel@...pniu.pl;
> luto@...nel.org; alex.hung@...onical.com; platform-driver-
> x86@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 3/4] dell-wmi: Add information about other WMI event
> codes
> 
> On 22/06/2016 16:21, Mario_Limonciello@...l.com wrote:
> >> -----Original Message-----
> >> From: Pali Rohár [mailto:pali.rohar@...il.com]
> >> Sent: Wednesday, June 22, 2016 9:13 AM
> >> To: Limonciello, Mario <Mario_Limonciello@...l.com>
> >> Cc: gabriele.mzt@...il.com; mjg59@...f.ucam.org;
> dvhart@...radead.org;
> >> kernel@...pniu.pl; luto@...nel.org; alex.hung@...onical.com;
> platform-
> >> driver-x86@...r.kernel.org; linux-kernel@...r.kernel.org
> >> Subject: Re: [PATCH 3/4] dell-wmi: Add information about other WMI
> event
> >> codes
> >>
> >> On Wednesday 22 June 2016 13:40:57 Mario_Limonciello@...l.com
> wrote:
> >>>>> You aren't seeing this on the DSDT of your Latitude right?
> >>>>
> >>>> Yes, I do not see it on Latitude.
> >>>
> >>> Thanks, the usage of this scan code is specific to consumer BIOSes.
> >>>
> >>>>
> >>>>> Gabriele,
> >>>>>
> >>>>> Your machine is from the year before XPS switched over to running
> the
> >>>>> Dell business client (eg Latitude, Precision, Optiplex) BIOS.
> >>>>>
> >>>>> The EC in that machine does have support for "Battery Health" via that
> >>>>> scancode.  On Windows it's used for relaying battery information to an
> >>>>> application called Quick Set.
> >>>>
> >>>> Do you have some details when it is send to OS? And how to read that
> >> that
> >>>> "battery health"?
> >>>
> >>> When a battery is removed or inserted this event is supposed to be
> >> received
> >>> by quickset over WMI and then Quickset will re-read battery
> information.
> >>
> >> So event is sent only if battery is removed or inserted?
> >>
> >
> > Yeah, that's what my spec says, I haven't tested this on actual system to
> see.
> >
> > I'm guessing what's going on is that during suspend ACPI battery drops
> > off system and comes back up on resume.
> >
> > Maybe Gabriele can comment if any other times were noticed, but in any
> > case I think it's appropriate for dell-wmi driver when receiving this on WMI
> > to not do anything.  Sending KEY_BATTERY would be wrong behavior.
> 
> I think I saw the event only after resume, but I don't read my dmesg
> that often to notice other special cases. Surely it's not related to
> any hotkey nor actual battery removal.
> 
> FYI I have a "battery button" and the associated code is 0xe007. I
> guess most of the laptop nowadays use that code for QuickSet, given
> that the entry for it was added to dell-wmi.c back in 2009.

Ah yes to make sure that's clear - that battery button is 
"Battery Health Meter". For QuickSet that function was for just showing
a little popup with remaining battery life.  For Linux I do think KEY_BATTERY
is still appropriate there.

> 
> I would also like to remind that my laptop receives four WMI events
> with code 0xe00e after resume. If we send an input event for each
> WMI event with code 0xe00e, I'd get four bogus button keypresses.

Yep, exactly why dell-wmi should just ignore this code.