Touchpad accel, spirals and xset

[James Zaki]

>> To prove, first turn off how the existing module triggers
>> recalibrations

> Reproduced without changing parameters or a nose.

Turning off the recalibrations was just to allow miscalibration to persist
for demonstration purposes. Ie, starting from first principles to show my
reasoning.



> I agree, it does seem that the calibration as a result of jumpiness
> might cause symptoms.

One thing I realised I could have emphasised is that the attempted
recalibration based on jumpiness is self perpetuating. Much like why
post_interrupt_delay didn't work. We're trying to think of things the device
developers would have already thought about.



> I can't think of a way to know when it is safe to recalibrate.

That is where I explained what was described as "spew", being helpful.

I just fired up the tech
specs<http://wiki.laptop.org/go/Image:KGDMFA001-non-confidential.pdf>(the
xo displays it correctly), and page 14 has the point about auto self
recalibration...

---
7) Automatic calibration setting command Enable/Disable       *C ver

   This command sets whether to do the calibration automatically when the
following states are generated.
   a. The high-speed operation not generated in the normal operation when
continuing.
   b. When you continuously generate the same position for ten seconds or
more.
----

For (b), 10 seconds is a long time.
But does anyone know about (a), and if/why we do/dont use auto calib without
the firmware module recalibs?



2010/1/21 James Cameron <quozl at laptop.org>

> On Thu, Jan 21, 2010 at 01:30:06AM +0100, James Zaki wrote:
> > The first thing I suspect most people do while waiting for the gui to
> > become responsive is try to move the curser.
>
> Yes, I've seen children do that.  Or press keyboard keys hoping it will
> go faster booting.  It seems to work for them because their perception
> of time is altered by interacting.
>
> > The init of the psmouse module triggers a calibration.
>
> Tested ... holding a finger on the touchpad during boot ... does cause
> jumpyness.
>
> > To prove, first turn off how the existing module triggers
> > recalibrations (I will explain the problem with one of them in a
> > moment)
> > ---
> > cd /sys/module/psmouse/parameters
> > echo 0 > jumpy_delay; echo 0 >spew_delay
> > ---
> >
> > Now give your xo a 5-finger-salut. The regular 4-finger-salut is here
> > but just before hitting that final fn key, try rest a finger on the
> > touchpad (the nose squished a bit also works too). The bigger the
> > touch, the greater areas are miscalibrated.
>
> Reproduced without changing parameters or a nose.
>
> > One way to reproduce was with a finger in one corner tap the other
> > corner whilst lifting the first finger. Doing something like this a
> > few times (basically triggering the recalibrate by imperfect use) will
> > cause the calibration to occur whilst your fingers are there.
>
> Reproduced easily.  (all above 802 on XO-1)
>
> I agree, it does seem that the calibration as a result of jumpiness
> might cause symptoms.
>
> I can't think of a way to know when it is safe to recalibrate.
>
> --
> James Cameron
> http://quozl.linux.org.au/
>
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