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SubjectRe: [PATCH 1/4] Adding documention
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.


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