Hi, On Thu, Jan 15, 2015 at 08:36:44AM +0100, Dr. H. Nikolaus Schaller wrote: > > 1. Perform conversion in input core rather than individual drivers. I > > think we should allocate a new bitmaps for some transformations and have > > the code do X/Y flip/clip of the coordinates. > > Do you have a suggestion where this should be (I have no clue how > the input system works or is structured - we just know how to extend a > driver that uses it)? > > > 2. Standardize on bindings. We already have of-touchscreen.c doing > > rudimentary parsing, we shoudl look into extending it rather than > > creating myriad of driver-specific bindings. > > Ok, looks reasonable. Documentation is in Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt > > Also, do we need swap and flip or do we simply need rotation (like the > > proposed Broadcom iproc driver has)? > > Well, since the DT should describe hardware, there are 3 sets of wires which > can have a cross-over: X+ and X-, Y+ and Y-, X and Y. > > So IMHO hardware has no “rotation”, just crossover of wires. Rotation is an > interpretation of the result of these connections in combination with some > panel the touch is glued to and should therefore not be represented in the DT. > > As a result we have proposed a scheme without explicit rotation. We specify what > coordinates X- and X+ should report at their ends (min, max) because the DT > programmer has to specify them anyways. Flipping is a result of defining these > coordinates in an ascending or descending way. Only swapping of the X and Y > wires can’t be implicitly defined so it has its own property. So the scheme we > have proposed tries to optimize the efforts needed to adapt new boards and write > DTs and focus the DT on hardware description. > > As a bonus we also specify the min and max value to be reported for the touch > pressure (Z axis) using the same basic principle. > > And it is a pure add-on on top of the existing driver so that it attempts not > to break existing device trees. from what I can see there are no in-tree-users using any of the new properties. > Maybe could you accept it as a first step for this specific driver (and let’s do > the big standardization work later on)? That does not work, since you create an ABI. -- Sebastian -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
