On 10/20/09 09:21, Somebody in the thread at some point said:
We have problems when we don't have much pressure and in this case
there is a lot of noise and the events that are reported by the driver
are actually noise. This noise would be more common at pen-down before
the adc readings settle and at pen-up.
Hi Nelson -
Just a FYI, on the board I have been working on there is a capacitive
sensor, AD7174. I wrote a driver for it which again uses the in-kernel
median filter (the original Openmoko version I wrote chopped out at the
moment) heavily and with really excellent results. The median filters
are pretty much like magic for certain common kinds of noise.
However, I just drop the median filter code into my tree in
drivers/input/misc at the moment. What would be really a good result I
think is if the filters turned up in ./lib in an easily reusable way.
I think maybe it's a mistake to focus on the in-kernel filters being
good for a particular touchscreen technology or even specifically
touchscreens. I am sure other drivers doing something completely
different with noisy instantaneously sampled data, that won't fit into
tslib worldview at all, can also benefit from being able to clean up
data in a standardized way before passing it down as an input event or
back to the device or whatever. And once that's possible, touchscreen
drivers of any sort have the standardized option to use it too if they
have a reason.
Just a thought, good luck :-)
-Andy
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