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    SubjectRe: [PATCHv3 1/5] Input: add common DT binding for touchscreens
    On Tue, May 06, 2014 at 01:04:12AM +0200, Sebastian Reichel wrote:
    > On Mon, May 05, 2014 at 12:51:39PM -0700, Dmitry Torokhov wrote:
    > > On Mon, May 05, 2014 at 12:41:26PM -0700, Tony Lindgren wrote:
    > > > * Sebastian Reichel <sre@kernel.org> [140425 16:56]:
    > > > > Add common DT binding documentation for touchscreen devices and
    > > > > implement input_parse_touchscreen_of_params, which parses the common
    > > > > properties and configures the input device accordingly.
    > > > >
    > > > > The method currently does not interpret the axis inversion properties,
    > > > > since there is no matching flag in the generic linux input device.
    > > > >
    > > > > Signed-off-by: Sebastian Reichel <sre@kernel.org>
    > > > > ---
    > > > > .../bindings/input/touchscreen/touchscreen.txt | 27 +++++++++++++++++
    > > > > drivers/input/input.c | 34 ++++++++++++++++++++++
    > > > > include/linux/input.h | 8 +++++
    > > > > 3 files changed, 69 insertions(+)
    > > > > create mode 100644 Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
    > > > >
    > > > > diff --git a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
    > > > > new file mode 100644
    > > > > index 0000000..d8e0616
    > > > > --- /dev/null
    > > > > +++ b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
    > > > > @@ -0,0 +1,27 @@
    > > > > +General Touchscreen Properties:
    > > > > +
    > > > > +Optional properties for Touchscreens:
    > > > > + - touchscreen-size-x : horizontal resolution of touchscreen
    > > > > + (in pixels)
    > > > > + - touchscreen-size-y : vertical resolution of touchscreen
    > > > > + (in pixels)
    > > > > + - touchscreen-max-pressure : maximum reported pressure (arbitrary range
    > > > > + dependent on the controller)
    > > > > + - touchscreen-fuzz-x : horizontal noise value of the absolute input
    > > > > + device (in pixels)
    > > > > + - touchscreen-fuzz-y : vertical noise value of the absolute input
    > > > > + device (in pixels)
    > > > > + - touchscreen-fuzz-pressure : pressure noise value of the absolute input
    > > > > + device (arbitrary range dependent on the
    > > > > + controller)
    > >
    > > Fuzz seems like linux-specific property, not generic one.
    >
    > I don't know about the term "fuzz", but the idea is pretty generic
    > IMHO. It's similar to debouncing switches/buttons.

    OK, fair enough.

    >
    > > > > + - touchscreen-inverted-x : X axis is inverted (boolean)
    > > > > + - touchscreen-inverted-y : Y axis is inverted (boolean)
    > > >
    > > > We probably also need something to swap x and y depending on the
    > > > display orientation in addition to the touchscreen-inverted-x and y.
    > > > Just swapping x and y is not enough depending if we rotate by 270
    > > > degrees instead of 90 degrees.
    > > >
    > > > Naturally that part can be added later.
    > >
    > > So far we've been relying on upper layers (such as tslib) to perform
    > > such transformations rather than re-implementing it in every driver. Are
    > > we saying that we need to implement this in input core?
    >
    > I would appreciate to add this later to move on with this patchset.
    > Having the N900's touchscreen working via DT in 3.16 would be nice
    > now that the display is working :)
    >

    Please remove the "inverted" bits and move touchscreen OF parsing into a
    separate file/module, similarly to support for sparse and matrix keymaps
    that we have - it does not really belong to input core.

    Thanks.

    --
    Dmitry


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