Synaptics multitouch coming - maybe

The Linux driver for Synaptics touchpads does not currently support multitouch mode for the usual reason: Synaptics has not deigned to tell the world how to actually use its hardware. There is hope for change, though: Chase Douglas has recently posted a set of Synaptics driver patches which add touchpad support based on information obtained through reverse engineering. There are evidently still a few glitches to work out, but the mode appears to work. Alas, that does not necessarily mean we'll have Synaptics multitouch support in the near future; the real difficulties may be outside of the technical realm.

When Chase posted his patches, Takashi Iwai - better known for his ALSA sound driver work - responded that he had also worked on multitouch support:

In the ensuing discussion, it became clear that Chase's patch was, in fact, Takashi's patch with some improvements added. Takashi had apparently posted the patch set once before Novell legal called a halt to the exercise; that work had been stashed in a Launchpad page until Chase stumbled across it, made some improvements, and resubmitted the code. (Just to be clear: it does not appear that Chase was trying to take credit for somebody else's work; he just hadn't understood the original source of the code).

Evidently, Takashi sees the independent posting of the code as being sufficient to get around Novell legal's objections to its merging; he responded with enthusiasm despite being allegedly on vacation. Chase's kernel patches have been topped up with a series of X.org patches taking advantage of the new kernel support and adding user-level support for nice things like three-finger and "pinch" gestures. All of this code has seemingly been waiting for its chance to escape into the wild; all it took was for somebody else to start pushing the kernel-side code.

So it seems that the floodgates are open and multitouch support on Synaptics devices will be available to all. But there could yet be a catch. As Chase noted: "If you're the originator of the work, and my patch is accepted, I think we'll need your SOB on it." Without a signoff from Takashi, this code may not be accepted into the mainline. Takashi has suggested that his signoff from the initial posting could be used, but he appears to be unwilling to repost the code with a signoff now.

And that's where the trouble could come: your editor has had no contact with Novell's legal department and has no special knowledge, but it would not be surprising to learn that the concerns that department had about this code might not be swept aside quite so easily. It's possible that the new signoff from Takashi might not be forthcoming. Or, possibly, distributors will get cold feet for the same reason that Novell legal did and decide not to enable the feature. This code has been in the wild for some months now, but it has not found its way into users' systems; the increasing attention being paid to it now may not be enough to change that fact.

The inability to use Takashi's code - if, indeed, it comes to that - would not be a huge problem. The important thing is the information on how the hardware works; given that, some energetic hacker would undoubtedly reimplement the changes in short order. Patent concerns could be harder to work around, though. Without knowledge of which patents were at issue, it's hard to say how big an obstacle they could be. By some accounts, multitouch interfaces in general are patented, though that does not seem to have stopped some companies from incorporating such interfaces into their products. If it stops nervous Linux distributors, though, Linux users as a whole will be the losers.

That, of course, is the nature of the software patent system. But the scenario described above is highly speculative at this point. The important thing is that the code (along with the associated hardware information) is out there and available for those who would incorporate it into their systems. Hopefully it will be more widely distributed soon. Unfortunately, the wait for those nice nice wall-size displays may be just a little bit longer.