Message-ID: <4D0A1AD5.1070200@euromail.se>
Date: Thu, 16 Dec 2010 14:57:41 +0100
From: Henrik Rydberg <rydberg@euromail.se>
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To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
CC: Peter Hutterer <peter.hutterer@who-t.net>, Jiri Kosina <jkosina@suse.cz>,
        Ping Cheng <pingc@wacom.com>, Chris Bagwell <chris@cnpbagwell.com>,
        Chase Douglas <chase.douglas@canonical.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC v2] input: Introduce device information ioctl
References: <1292440807-18502-1-git-send-email-rydberg@euromail.se> <20101216002941.GC4952@salty.local> <20101216004358.GA22066@core.coreip.homeip.net>
In-Reply-To: <20101216004358.GA22066@core.coreip.homeip.net>
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>>>  /*

>>> + * Device properties and quirks
>>> + */
>>> +
>>> +#define INPUT_PROP_POINTER		0x00	/* needs a pointer */
>>> +#define INPUT_PROP_DIRECT		0x01	/* direct object manipulation */
>>
>> fwiw, I think the common term for these is "direct input devices", at least
>> that's how a lot of the research literature refers to them. Might be good to
>> use the same term.
>>
>> either way, not sure about this one.  I've worked with devices that were
>> indirect by nature but used directly. e.g. the magic touchpad could quite
>> easily be used as direct input device with an top-down projector. the
>> decision to use it as an indirect device is a UI decision.
>> Likewise, some mountable direct-touch touchscreens can be used indirectly if
>> the touchscreen isn't mounted straight on the display. This is very much a
>> setup-specific property and I'm not sure about the value of this
>> information.
> 
> All of these "props" would have no reflection on the event stream
> generated by the device, and exist solely for the benefits of userspace
> consumers to help them set up the device automatically and interpret the
> data appropriately. As such, if someone uses touchscreen as a tablet, I
> believe userspace should allow it, but at the price of manual setup.
> 
> If we start seeing cuch devices we could consider EVIOCSPROPS so
> infrastructure (udev) could adjust the properties so that upper levels
> (X) can still use the data to set up devices properly.
> 
> What do you think?
> 


I am not 100% convinced. If other things like touchscreen orientation would fit
into that flow as well, then I'd say yes. But if there will always be a
difference between a default device setting and a system-wide device setting,
then it seems reasonable to handle this in userspace.

Henrik
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