Re: [RFC v2] input: Introduce device information ioctl

[Henrik Rydberg <rydberg@euromail.se>]

>>>  /*

>>> + * 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