Le lundi 11 juillet 2005 à 13:00 +0200, Vojtech Pavlik a écrit : > On Mon, Jul 11, 2005 at 12:39:31PM +0200, Stelian Pop wrote: > > > > > Using a function like > > > > > > > > return (x_old * 3 + x) / 4; > > > > > > > > eliminates the need for a FIFO, and has similar (if not better) > > > > properties to floating average, because its coefficients are > > > > [ .25 .18 .14 .10 ... ]. > > > > > > Agreed. > > > > Except that this does not work well enough. > > I guess the quick motion compensation in input bites you. The above > equation should do even more smoothing than regular 4-point floating > average.
Possible. The 'fuzz' parameter in input core serves too many usages ihmo. Let me try removing the quick motion compensation and see... > > I already thought about this, one problem is that the sensors do not > > report the pressure but only the amount of surface touched. A person > > with thick fingers will always generate higher pressures then one with > > thin ones, no matter how hard they push on the touchpad. > > That's what all other touchpads do. I thought the hardware is capable of calculating real pressure... > > I don't think this value is reliable enough to be reported to the > > userspace as ABS_PRESSURE... > > I believe it'd still be more useful than a two-value (0 and 100) output. Ok, I'll do it. > > + /* > > + * in the future, we could add here code to search for > > + * a second finger... > > + * for now, scrolling using the synaptics X driver is > > + * much more simpler to achieve. > > + */ > > This could be quite useful, too, for right and middle button taps (2 and > 3 fingers) - since the Macs lack these buttons. Indeed. But this can be a later improvement, let's make one finger work for now :) Stelian. -- Stelian Pop <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
