The wcmLinkTouchAndPen function is responsible for associating the pen and
touch interfaces of a tablet. This association can be tripped up if multiple
devices with the same name are connected, so it includes code to prevent
linking to a device which already has been linked up. However, the condition
also checks that the device being considered is a tablet (i.e., stylus/eraser/
cursor; not pad/touch). This latter check seems nonsensical: it allows devices
to link to the first touch device they find, even if that device is already
linked up.
Disallowing multiple links to the same device prevents all three pen/touch/pad
devices from having wcmTouchDevice set up, however. Leaving the stricter
condition as-is could cause devices to be linked up incorrectly (e.g. if the
X server has {touch1, pen1, pad1, touch2, pen2, pad2}, then touch1 and pen1
would get linked, but pad1 and touch2 would get linked, and pen2/pad2 left
unlinked!). To prevent this, we disallow linking of pad interfaces, which
should not be a problem since the pad shouldn't need to use the wcmTouchDevice
variable.
Fixes: 8bb519ef2b ("Update wcmTouchDevice for touch interface")
Signed-off-by: Jason Gerecke <[email protected]>
---
src/wcmConfig.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/wcmConfig.c b/src/wcmConfig.c
index 2402952..f85f1ca 100644
--- a/src/wcmConfig.c
+++ b/src/wcmConfig.c
@@ -492,6 +492,12 @@ static Bool wcmLinkTouchAndPen(InputInfoPtr pInfo)
WacomCommonPtr tmpcommon = NULL;
WacomDevicePtr tmppriv = NULL;
+ if (IsPad(priv))
+ {
+ DBG(4, priv, "No need to link up pad devices.\n");
+ return FALSE;
+ }
+
/* Lookup to find the associated pen and touch */
for (; device != NULL; device = device->next)
{
@@ -504,7 +510,7 @@ static Bool wcmLinkTouchAndPen(InputInfoPtr pInfo)
DBG(4, priv, "Considering link with %s...\n", tmppriv->name);
/* already linked devices */
- if (tmpcommon->wcmTouchDevice && IsTablet(tmppriv))
+ if (tmpcommon->wcmTouchDevice)
{
DBG(4, priv, "A link is already in place. Ignoring.\n");
continue;
--
2.15.1
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