Thread (10 messages) 10 messages, 2 authors, 2023-05-17

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

From: Krzysztof Kozlowski <hidden>
Date: 2023-05-17 09:01:04
Also in: linux-devicetree, lkml

On 16/05/2023 11:03, Javier Carrasco wrote:
On 16.05.23 10:13, Krzysztof Kozlowski wrote:
quoted
On 16/05/2023 10:10, Krzysztof Kozlowski wrote:
quoted
On 15/05/2023 17:00, Javier Carrasco wrote:
quoted
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 <redacted>
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.

The feature describes the hardware, not driver. To understand what does
it mean, look from hardware point of view - does it have some virtual
area or clipped area?
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.
But what if actual physical buttons are added there? You still would
have clipped/virtual area, just without virtual buttons.
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.
To me, word "virtual" suggests something which does not exist. Kind of
something abstracted or symbolic. Opposite to "real". Here all this
really exists. You have physical stickers on the touchscreen.

Maybe this should be then "dedicated"? or "isolated"?

Or just "overlay-area"?
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.
Best regards,
Krzysztof
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