[OE-core] [PATCH] udev: generalize the check in touchscreen rule

[Marko Katić]

Current tslib indeed does use ABS_PRESSURE to signal applied pressure.
BTN_TOUCH is only used to indicate pen up events. This happens in the
input_raw module.
Tslib could be modified to check whether the underlying input device
supports ABS_PRESSURE. if not, it shoud use BTN_TOUCH to signal applied
pressure.


On Wed, Apr 11, 2012 at 12:16 PM, Richard Purdie <
richard.purdie at linuxfoundation.org> wrote:

> On Wed, 2012-04-11 at 10:59 +0200, Andrea Adami wrote:
> > On Mon, Apr 2, 2012 at 11:35 PM, Andrea Adami <andrea.adami at gmail.com>
> wrote:
> > > * The actual rule only works for devices reporting ts pressure
> > > * and ignores the other touchscreens (happens e.g. on ipaq h1940).
> > > * a0,1,*18   a = absolute axes (ABS_X 0x00 ABS_Y 0x01 ABS_PRESSURE
> 0x18)
> > > * (see include/linux/input.h)
> > > *
> > > * Guidelines for touchscreen seem suggesting only ABS_X and ABS_Y are
> mandatory
> > > * (http://kernel.org/doc/Documentation/input/event-codes.txt)
> > > *
> > > * Bump PR
> > >
> > > Signed-off-by: Andrea Adami <andrea.adami at gmail.com>
> > > ---
> > >  meta/recipes-core/udev/udev/local.rules |    3 +--
> > >  meta/recipes-core/udev/udev_164.bb      |    2 +-
> > >  2 files changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/meta/recipes-core/udev/udev/local.rules
> b/meta/recipes-core/udev/udev/local.rules
> > > index 625e49a..49e8d28 100644
> > > --- a/meta/recipes-core/udev/udev/local.rules
> > > +++ b/meta/recipes-core/udev/udev/local.rules
> > > @@ -31,5 +31,4 @@ KERNEL=="rtc0", SYMLINK+="rtc"
> > >  ACTION=="add", DEVPATH=="/devices/*", ENV{MODALIAS}=="?*",
> RUN+="/sbin/modprobe $env{MODALIAS}"
> > >
> > >  # Create a symlink to any touchscreen input device
> > > -SUBSYSTEM=="input", KERNEL=="event[0-9]*",
> ATTRS{modalias}=="input:*-e0*,3,*a0,1,*18,*", SYMLINK+="input/touchscreen0"
> > > -
> > > +SUBSYSTEM=="input", KERNEL=="event[0-9]*",
> ATTRS{modalias}=="input:*-e0*,3,*a0,1,*", SYMLINK+="input/touchscreen0"
> > > diff --git a/meta/recipes-core/udev/udev_164.bbb/meta/recipes-core/udev/
> udev_164.bb
> > > index c5813ec..0462ff2 100644
> > > --- a/meta/recipes-core/udev/udev_164.bb
> > > +++ b/meta/recipes-core/udev/udev_164.bb
> > > @@ -1,6 +1,6 @@
> > >  include udev.inc
> > >
> > > -PR = "r13"
> > > +PR = "r14"
> > >
> > >  SRC_URI += "file://udev-166-v4l1-1.patch"
> > >
> > > --
> > > 1.7.3.4
> > >
> >
> > Bump
> >
> > I'm not linux-input specialist but this fix looks rather harmless.
>
> I'm not 100% convinced about that. There needs to be some mechanism to
> signal to the system when there is pressure applied to the screen and
> when pressure was released. I think there are two ways you can do this,
> BTN_TOUCH and ABS_PRESSURE. Regardless of what the input events codes
> say, I'm really more interested in what tslib accepts.
>
> This code has been like this for a long time and I'm surprised that if
> there were issues it wasn't patched long before now. I'm therefore left
> wondering if the touchscreen driver you're using is doing the right
> things.
>
> Cheers,
>
> Richard
>
>
>
>
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