Re: mouse driver bug in 2.6.0-test7?

[4Front Technologies <dev@opensound.com>]

Vojtech Pavlik wrote:
> On Tue, Oct 14, 2003 at 01:04:03PM -0700, 4Front Technologies wrote:
> 
> 
>>>Patch considered. I'll up the samplerate default to 80, but not more,
>>>since samplerates above that cause trouble for a lot of people (keyboard
>>>doesn't work when you're moving the mouse).
>>>
>>>The "set lower rate in case ..." part of the patch doesn't make sense.
>>>If the user gives a too low (less than 10) samples per second, then the
>>>original code will try to set 0, which is stupid, but harmless. The
>>>added code will try to access beyond the bounds of the rates[] array.
>>
>>
>>Hi Martin/Vojtech,
>>
>>Martin, many thanks for your fix - it works perfectly now.
>>
>>Oddly enough the sample rate of 200 seems to have fixed the problem.
>>Vojetech,  Martin's fixes are fully functional.
> 
> 
> Not completely. One reason wht the sample rate of 200 probably fixed the
> problem is that you have very high acceleration settings in X.
> 
> Since with report rate 200 you get a medium speed movement as
> 
> +1 +1 +1 +1 +1 +1 +1 +1 +1
> 
> events, and with report rate 60 you get
> 
>        +3      +3       +3
> 
> and the X mouse acceleration code is stupid enough to judge the mouse
> speed from the event VALUE only, it thinks the mouse is moving much
> faster in the second case.
> 
> You need to up the acceleration threshold (or disable acceleration
> completely).
> 
> This also means that with report rate of 200, mouse acceleration is more
> or less disabled, since you get +1's only even at quite high speeds of
> mouse movement.
> 


Vojtec/Martin

You're right, the original problem still remains. The tracking is still
2x compared to Linux 2.4.

Here's how I did the measurement.
Get a foot-scale and start xev. Ajust xev so that the coordiates of the
window are 0,y (y is y-axis - don't care) in the X root window (my res is 1024x768).

Now align the mouse so that it shows 0,0 on the top left corner in the xev window
and move the mouse exactly one 1 inch and you'll see that under Linux 2.6.0-test7
the x axis position is at something like 325. However repeating the same test under
Linux 2.4.22 puts the mouse at x axis position 170 (gives me a accelearation factor
of about 2x).

This is a horribly crude test but it explains my problem that the mouse driver isn't
tracking correctly.


Hope this helps figuring out the problem.


best regards

Dev Mazumdar
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