Re: [PATCH v2 2/4] dt-bindings: touchscreen: add virtual-touchscreen and virtual-buttons properties

[Javier Carrasco <javier.carrasco@wolfvision.net>]

On 16.05.23 10:13, Krzysztof Kozlowski wrote:
> On 16/05/2023 10:10, Krzysztof Kozlowski wrote:
>> On 15/05/2023 17:00, Javier Carrasco wrote:
>>> The virtual-touchscreen object defines an area within the touchscreen
>>> where touch events are reported and their coordinates get converted to
>>> the virtual origin. This object avoids getting events from areas that
>>> are physically hidden by overlay frames.
>>>
>>> For touchscreens where overlay buttons on the touchscreen surface are
>>> provided, the virtual-buttons object contains a node for every button
>>> and the key event that should be reported when pressed.
>>>
>>> Signed-off-by: Javier Carrasco <javier.carrasco@wolfvision.net>
>>> ---
>>
>>
>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> Apologies, second thoughts - why calling all this binding and properties
> "virtual"? That's the word which immediately raises questions, because
> bindings are only for real things, not virtual.
> 
> Touchscreen is just clipped, not virtual, so maybe "clipped-area"
> instead of virtual-touchscreen? Buttons are real, so maybe just "buttons"?
> 
> Best regards,
> Krzysztof
> 
I guess it is a matter of perspective. For a user the buttons and the
clipped area are 100% real, but for a driver developer they are virtual
in the sense that there is not an "active" hardware behind apart from
the original touchscreen.

I just wanted to avoid misunderstandings when implementing this feature
for other drivers. One might wonder if the touchscreen now has
mechanical keys attached to it. With the "virtual-" prefix it is clear
that the objects are not additional pieces of hardware or extensions of
the touchscreen functionality.

For the virtual-touchscreen your point is stronger because there is
indeed a real touchscreen hardware no matter the area you define, but my
approach was keeping homogeneous names for the different objects in case
some new ones might appear in the future: every object that gets on top
of the touchscreen area is virtual, so add a new object type and name it
virtual-xxx.

I have nothing against about doing some renaming and I will do it if it
is required, but with the documentation I think it is now more clear
what everything means and in the end it might make more sense for the
drivers so they can differentiate between real and virtual devices.