Synaptics Palm Detection patch

debug_palm.diff

diff -aur xf86-input-synaptics-1.8.0/src/synaptics.c xf86-input-synaptics-1.8.0.new/src/synaptics.c
--- xf86-input-synaptics-1.8.0/src/synaptics.c	2014-05-12 21:17:46.000000000 -0400
+++ xf86-input-synaptics-1.8.0.new/src/synaptics.c	2014-05-30 14:49:39.123104990 -0400
@@ -1793,28 +1793,19 @@
 
     /* palm detection */
 
-    if ((hw->z > para->palm_min_z) && (hw->fingerWidth > para->palm_min_width))
+    if ((hw->z > para->palm_min_z))
         return FS_BLOCKED;
 
-    if (hw->x == 0 || priv->finger_state == FS_UNTOUCHED)
-        priv->avg_width = 0;
-    else
-        priv->avg_width += (hw->fingerWidth - priv->avg_width + 1) / 2;
-
     if (finger != FS_UNTOUCHED && priv->finger_state == FS_UNTOUCHED) {
-        int safe_width = MAX(hw->fingerWidth, priv->avg_width);
-
         if (hw->numFingers > 1 ||       /* more than one finger -> not a palm */
-            ((safe_width < 6) && (priv->prev_z < para->finger_high)) || /* thin finger, distinct touch -> not a palm */
-            ((safe_width < 7) && (priv->prev_z < para->finger_high / 2))) {     /* thin finger, distinct touch -> not a palm */
+            (priv->prev_z < para->finger_high) || /* thin finger, distinct touch -> not a palm */
+            (priv->prev_z < para->finger_high / 2)) {     /* thin finger, distinct touch -> not a palm */
             /* leave finger value as is */
         }
         else if (hw->z > priv->prev_z + 1)      /* z not stable, may be a palm */
             finger = FS_UNTOUCHED;
         else if (hw->z < priv->prev_z - 5)      /* z not stable, may be a palm */
             finger = FS_UNTOUCHED;
-        else if (hw->fingerWidth > para->palm_min_width)        /* finger width too large -> probably palm */
-            finger = FS_UNTOUCHED;
     }
     priv->prev_z = hw->z;
 

PKGBUILD

# $Id: PKGBUILD 213056 2014-05-18 13:44:18Z andyrtr $
# Maintainer: Jan de Groot <jgc@archlinux.org>
# Contributor: Tobias Powalowski  <tpowa@archlinux.org>
# Contributor: Thomas Bächler <thomas@archlinux.org>
# Contributor: Alexander Baldeck <alexander@archlinux.org>

pkgname=xf86-input-synaptics
pkgver=1.8.0
pkgrel=2
pkgdesc="Synaptics driver for notebook touchpads"
arch=('i686' 'x86_64')
license=('custom')
url="http://xorg.freedesktop.org/"
depends=('libxtst' 'mtdev' 'libevdev')
makedepends=('xorg-server-devel' 'X-ABI-XINPUT_VERSION=20' 'libxi' 'libx11' 'resourceproto' 'scrnsaverproto')
conflicts=('xorg-server<1.15.0' 'X-ABI-XINPUT_VERSION<20' 'X-ABI-XINPUT_VERSION>=21')
replaces=('synaptics')
provides=('synaptics')
conflicts=('synaptics')
groups=('xorg-drivers' 'xorg')
backup=('etc/X11/xorg.conf.d/50-synaptics.conf')
source=(http://xorg.freedesktop.org/releases/individual/driver/${pkgname}-${pkgver}.tar.bz2
        add_tapbuttons.diff
		debug_palm.diff)
sha256sums=('9bf27632aaa6c5e62621ca9c2ca00f9b309c85b039ee33cd592b189fc872c37a'
            '5298d3e871db3768b34cf8516d3f53f9291202e2ea5de3300256e1cd9119a1ec'
            'bc7ea1967a31c4fe5ebdfec7154eeba88c2fac93915f15e37094e4e20bf5fac7')

build() {
  cd ${pkgname}-${pkgver}
  
  # * upstream disabled tapping by default if a physical left button is present - see FS#33282
  # * enable MatchDevicePath directive by default - FS#33291
  patch -Np1 -i ${srcdir}/add_tapbuttons.diff
  # palm detection debugging
  patch -p1 -i ${srcdir}/debug_palm.diff
  
  ./configure --prefix=/usr
  make
}

package() {
  cd ${pkgname}-${pkgver}
  make DESTDIR="${pkgdir}" install
  install -m755 -d "${pkgdir}/etc/X11/xorg.conf.d"
  install -m644 conf/50-synaptics.conf "${pkgdir}/etc/X11/xorg.conf.d/"
  install -m755 -d "${pkgdir}/usr/share/licenses/${pkgname}"
  install -m644 COPYING "${pkgdir}/usr/share/licenses/${pkgname}/"

  rm -rf "${pkgdir}/usr/share/X11"
}

Hi. how do I apply this patch?

Check out xf86-input-synaptics from the Arch Build System, save the patchfile to the directory and overwrite the PKGBUILD with this one before building.

Thanks for this patch! This issue was driving me nuts and basically made my brand new laptop unusable. You have made it enjoyable to use again!

Question from a noob, how do I apply this patch on Ubuntu? I cannot find how to build the PKGBUILD. Thanks!
(Apologies for commenting on an old thread, but being dissatisfied with libinput, I wanted to give this one a try.)