On Sun, 29 Aug 2010, Rafi Rubin wrote: > >> +---------- > >> + > >> +Note: values set at load time are global and will apply to all applicable > >> +devices. Adjusting parameters with sysfs will override the load time values, > >> +but only for that one device. > >> + > >> +The following parameters are used to configure filters to reduce noise: > >> + > >> +activate_slack number of fingers to ignore before processing events > >> + > >> +activation_height size threshold to activate immediately > >> +activation_width > >> + > >> +min_height size threshold bellow which fingers are ignored > >> +min_width both to decide activation and during activity > >> + > >> +deactivate_slack the number of "no contact" frames to ignore before > >> + propagating the end of activity events > >> + > >> +When the last finger is removed from the device, it sends a number of empty > >> +frames. By holding off on deactivation for a few frames we can tolerate false > >> +erroneous disconnects, where the sensor may mistakenly not detect a finger that > >> +is still present. Thus deactivate_slack addresses problems where a users might > >> +see breaks in lines during drawing, or drop an object during a long drag. > > > > > > Without contact tracking, it is hard to imagine activation filtering to work > > properly. I would advocate to remove this functionality from the driver, and add > > it in userspace instead. > > > > Henrik > > I don't think its quite time to remove these filters. There still isn't a > proper replacement that's readily accessible to most users. From what I've > heard many still use the wacom driver to support touch in X. > > Tracking only helps if you increase the activation slack to more than 1 contact > (the current default), and only if you assume the you will see ghosts span > multiple frames in two different locations, which may be even less likely than > seeing a ghost in one spot for two frames. > > Maybe in a few more months or another year, it will make more sense to remove > the filters from this driver. In the mean time, is it really preferable to > leave them undocumented? Agreed. I have now applied the patch, thanks Rafi. -- Jiri Kosina SUSE Labs, Novell Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
