Re: [PATCH v2 2/5] platform/x86: intel-vbtn: Support separate press/release events

From: "Stefan Brüns" <stefan.bruens@rwth-aachen.de>
To: Darren Hart <dvhart@infradead.org>
Cc: <platform-driver-x86@vger.kernel.org>,
	<linux-input@vger.kernel.org>,
	AceLan Kao <acelan.kao@canonical.com>,
	Andy Shevchenko <andy@infradead.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/5] platform/x86: intel-vbtn: Support separate press/release events
Date: Fri, 10 Nov 2017 02:58:36 +0100	[thread overview]
Message-ID: <1637751.MqEGyCB5Qi@pebbles> (raw)
In-Reply-To: <20171110013417.GB9783@fury>

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On Friday, November 10, 2017 2:34:17 AM CET Darren Hart wrote:
> On Thu, Nov 09, 2017 at 11:44:33PM +0100, Stefan Brüns wrote:
> > Currently all key events use autorelease, but this forbids use as a
> > modifier key.
> > 
> > As all event codes come in even/odd pairs, we can lookup the key type
> > (KE_KEY/KE_IGNORE) for the key up event corresponding to the currently
> > handled key down event. If the key up is ignored, we keep setting the
> > autorelease flag for the key down.
> 
> What is the use-case for using these buttons as modifiers? I'm picturing one
> of these devices in tablet mode, with a physical Windows button. What other
> action does a user want to modify by holding the Windows button down? Or is
> there another scenario we're trying to support here?

Windows/KEY_LEFTMETA can be used as a modifier key, e.g. in combination with 
the Volume Up/Down keys. On Windows, the default for Win + VolumeUp creates a 
screenshot.

You can also use this in combination with an onscreen keyboard. Pressing the 
hardware button with the hand holding the tablet and typing with the other 
hand on the OSK is probably easier than hitting both keys on the OSK.

Additionally, the Volume Up/Down currently do not autorepeat, as the key is
autoreleased on the press event. The XPS 12 does issue distinct press/release 
events, so this could be done properly. The same apparently holds for some 
other convertibles, see the links in Patch 1/5.

Kind regards,

Stefan

-- 
Stefan Brüns  /  Bergstraße 21  /  52062 Aachen
home: +49 241 53809034     mobile: +49 151 50412019

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