Messages in this thread | | | Date | Fri, 27 Aug 2010 14:06:29 +0200 | From | Henrik Rydberg <> | Subject | Re: [PATCH 1/4] Adding documention |
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On 08/26/2010 06:54 AM, Rafi Rubin wrote:
[...]
> +Parameters
> +---------- > + > +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
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