multitouch and synaptics clickpad status

Chase Douglas chase.douglas at
Wed Mar 30 07:29:08 PDT 2011

(Sorry for the line wrap or any ill formatted text. Thunderbird is buggy and won't show me messages when I have soo many unread :). I'm having to use Mail on OS X.)

On Mar 4, 2011, at 1:54 PM, Daniel Kurtz wrote:

> Back in October Chase Douglas [1] kicked off a flurry of patches and discussions on this list about adding Clickpad support, and some form of multitouch gesture processing (well, at least what is possible with Synaptics Advanced Gesture Mode) to the xf86-input-synaptics driver (and/or the kernel).  The patches were commented upon, and rehashed a little... but now everything seems to have died down - and, as far as I can tell, nothing has yet been accepted to xf86-input-synaptics upstream.
> [1] Starting with this:
> I also saw that in late December Henrik Rydberg submitted a patch [2] to linux-input, based on the discussions above, but which just added semi-mt support to the synaptics kernel driver.  This patch, too, has been sitting up there, but it looks as though it has not yet been accepted upstream.
> [2]
> Can anybody update the status of this new kernel driver, and/or the effort to use it from user space?

The synaptics kernel driver now has semi-mt support in 2.6.38.

> Are patches still being reviewed/tested/worked on by someone for xf86-input-synaptics to use AGM mode to improve clickpad performance?

This requires real multitouch support in the X synaptics input module, which will likely be merged when XInput 2.1 is being merged. That doesn't stop anyone from incorporating the multitouch data in the driver itself to enhance single touch usage, but I'd be surprised to see anything of that nature merged before there's full X mt support.

In Ubuntu Natty (11.04), we have a prototype of XInput 2.1 including support in X synaptics. On top of that we are adding a small bit of logic to make the special Dell Mini trackpads (AKA the "trackpad from hell") work better. This is only really possible because our prototype synaptics module has multitouch support. So there is work ongoing for this, and I plan on continuing to develop it and merge it into upstream X when XInput 2.1 is merged.

> Or was a decision made to not bother, and instead only focus on mtdev & xf86-input-multitouch?

mtdev is orthogonal to all this. The X multitouch work will depend upon mtdev itself. xf86-input-multitouch is also an interesting project, and I foresee a merging of code from their into synaptics when multitouch is added.

> What is the status of semi-mt support in mtdev?

mtdev's main purpose is to convert a non-slotted (touch tracking) protocol into a slotted (tracked) protocol. Semi-mt devices only operate through the slotted protocol, so mtdev just passes the data through it. No issues.

> What is the official status of xf86-input-multitouch, anyway?
> It doesn't appear to be an "official" X input driver, supported and maintained on this list.

You'd need to ask Henrik Rydberg (Cc'd).


-- Chase

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