Re: [PATCH 3/3] Input: synaptics - remove touches over button click area

[Takashi Iwai <tiwai@suse.de>]

At Mon, 11 Oct 2010 10:30:16 -0700,
Dmitry Torokhov wrote:
> 
> On Mon, Oct 11, 2010 at 07:10:33PM +0200, Takashi Iwai wrote:
> > At Mon, 11 Oct 2010 11:24:04 -0500,
> > Chris Bagwell wrote:
> > > 
> > > On Fri, Oct 8, 2010 at 9:58 AM, Chase Douglas
> > > <chase.douglas@canonical.com> wrote:
> > > > Now that we have proper multitouch support, we can handle integrated
> > > > buttons better. If we know the top of the buttons on the touchpad, we
> > > > can ignore any touches that occur within the touchpad area while a
> > > > button is clicked. It may be possible to get the button area by querying
> > > > the device, but for now allow the user to manually set it.
> > > >
> > > > A note on why this works: the Synaptics touchpads have pseudo touch
> > > > tracking. When two touches are on the touchpad, an MT touch packet with
> > > > just the X, Y, and pressure values is sent before a normal Synaptics
> > > > touch packet. When one touch is obviously in motion and the other is
> > > > stationary, the touchpad controller sends the touch in motion in the
> > > > normal packet and the stationary touch in the MT packet. Single touch
> > > > emulation is provided by the normal packet, so an action like clicking
> > > > a button and dragging with another finger still works as expected.
> > > >
> > > > Tested on a Dell Mini 1012 with synaptics_multitouch=1 and
> > > > synaptics_button_thresh=4100.
> > > >
> > > > Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
> > > > ---
> > > >  drivers/input/mouse/synaptics.c |   16 +++++++++++++++-
> > > >  1 files changed, 15 insertions(+), 1 deletions(-)
> > > >
> > > > diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> > > > index 7289d88..e67778d 100644
> > > > --- a/drivers/input/mouse/synaptics.c
> > > > +++ b/drivers/input/mouse/synaptics.c
> > > > @@ -49,6 +49,12 @@ module_param(synaptics_multitouch, bool, 0644);
> > > >  MODULE_PARM_DESC(synaptics_multitouch,
> > > >                 "Enable multitouch mode on Synaptics devices");
> > > >
> > > > +static int synaptics_button_thresh = YMIN_NOMINAL + YMAX_NOMINAL;
> > > > +module_param(synaptics_button_thresh, int, 0644);
> > > > +MODULE_PARM_DESC(synaptics_button_thres,
> > > > +                "Y coordinate threshold of integrated buttons on Synaptics "
> > > > +                "devices");
> > > > +
> > > >  /*****************************************************************************
> > > >  *     Stuff we need even when we do not want native Synaptics support
> > > >  ****************************************************************************/
> > > > @@ -463,6 +469,10 @@ static void synaptics_parse_hw_state(unsigned char buf[], struct synaptics_data
> > > >        }
> > > >  }
> > > >
> > > > +#define TOUCH_OVER_BUTTON(hw) (((hw).left || (hw).middle || (hw).right) && \
> > > > +                              (YMAX_NOMINAL + YMIN_NOMINAL - (hw).y > \
> > > > +                               synaptics_button_thresh))
> > > > +
> > > >  /*
> > > >  *  called for each full received packet from the touchpad
> > > >  */
> > > > @@ -477,7 +487,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
> > > >        synaptics_parse_hw_state(psmouse->packet, priv, &hw);
> > > >
> > > >        if (SYN_MULTITOUCH(priv, &hw)) {
> > > > -               if (hw.z > 0) {
> > > > +               if (hw.z > 0 && !TOUCH_OVER_BUTTON(hw)) {
> > > >                        input_report_abs(dev, ABS_MT_POSITION_X, hw.x);
> > > >                        input_report_abs(dev, ABS_MT_POSITION_Y,
> > > >                                         YMAX_NOMINAL + YMIN_NOMINAL - hw.y);
> > > > @@ -509,6 +519,10 @@ static void synaptics_process_packet(struct psmouse *psmouse)
> > > >                return;
> > > >        }
> > > >
> > > > +       /* If touch occurs over depressed button, ignore it */
> > > > +       if (TOUCH_OVER_BUTTON(hw))
> > > > +               hw.z = 0;
> > > > +
> > > >        if (hw.z > 0) {
> > > >                priv->num_fingers++;
> > > >                finger_width = 5;
> > > > --
> > > > 1.7.1
> > > >
> > > >
> > > 
> > > I'm convinced now that clickpad style touchpads can't work without
> > > multi-touch and something like logic in xf86-input-multitouch.
> > 
> > Actually Clickpad works without multi-touch patch.  With my patches to
> > synaptics, it worked in some level.  There are many restrictions (e.g.
> > pushing the button first then drag), though.
> > 
> 
> I am OK with devices not working perfectly with default/existing
> drivers, but we should allow enough functionality (movement, primary
> - left - click and so on) so that user can go through install and/or
> upgrade of  userpsace component.
> 
> This also mean that we need to have userspace component available before
> changing the behavior that will cause adverse effect for older setups.
> Of course if we could avoid degrading older setups that would be even
> better.

The xorg synaptics patches work with 2.6.34 or later kernel that contains
SYN_CAP_CLICKPAD() in kernel driver.

The question from now on is about the multi-touch patch, I'd say.
One concern is the compatibility.  The multi-touch is definitely
benefit for non-clickpad devices.  I guess integrating mtdev into xorg
synaptics would be a good way to go, while picking up the minimal
support for MT (like my patches) might be a quicker at this moment.

In anyway, I see no merit for implementing clickpad support in the
kernel driver for the time being, especially since the multi-touch can
be better supported in the user-space.


Takashi