Re: mousedev patch

[Vojtech P. <vo...@su...>]

On Tue, Jul 24, 2001 at 08:21:43PM -0700, Charles Duffy wrote:
> On Tue, Jul 24, 2001 at 07:59:32PM -0700, James Simmons wrote:
> > > This patch stops mousedev from dividing by zero when handling events
> > > from (faulty?) drivers which send ABS_* events but don't set
> > > dev->abs{min,max}.
> > 
> > Hm. I have done this :-/  Shouldn't it print a error instead?
> 
> Not necessarily -- situations can exist where the min/max absolute
> values are unavailable and the resolution of the touchpanel matches
> that of the LCD it covers (and thus no scaling is, literally, good
> scaling). While one could try have the user enter the appropriate
> value at configure- or module load-time, the easiest solution here is
> simply to allow the touchpanel driver not to provide a resolution if
> one is unavailable.

I don't think this is good. For absolute devices there should be a
defined range. It's not just mousedev who uses the values.

> The presumption that a touchpanel's resolution matches that of its
> correspending LCD is frequently correct -- I've got four touchpanel
> devices in the testing lab over here; not one of them has a resolution
> different from that of the LCD panel it's connected to.

I have a transparent Gunze touchpanel here whose physical resolution is
1024x1024 (although it has a 3:4 aspect ratio), on a 800x600 TFT screen.

So there exist panels for which you need to scale. But you shouldn't
need mousedev for touchpanels in the first place.

> Thus, I'd like to have this be Correct Behaviour for an event handler.
> (Some changes are also needed to tsdev.c; I'd be glad to provide
> them).

I think much better would be letting mousedev know both the correct
screen and touchpanel resolution.

-- 
Vojtech Pavlik
SuSE Labs