[PATCH libinput 0/4] some acceleration fixes, mostly for high DPI mice

[Peter Hutterer]

On Thu, Oct 30, 2014 at 04:34:12PM -0500, Derek Foreman wrote:
> The acceleration filter currently isn't particularly pleased with gaming mice.
> 
> They generally have high DPI (can be over 8000 DPI) and can have high update
> rates (1000+ per second).  This can result in the accel curve being biased
> heavily towards the high points on the accel curve.
> 
> This patch set allows a way to normalize the deltas to 400DPI so when the
> DPI setting of the mouse is correct, it should feel much the same as a
> normal mouse.
> 
> This is, of course, only a partial solution.  Setting a reasonable default
> is a massive problem that needs to be addressed in the future - for now
> we just set it to 400 (which may actually not be that prevalent any more
> but there doesn't seem to be such thing as a "standard" DPI mouse).

Thanks, I've pushed 1 to 3 (with added comments), not quite happy with
4 yet. As a configuration interface, it's mismatched with the usual quartett
of hooks that we provide for all other config options.

But I think providing a visible API may not be the right approach here
anyway. One idea I had here was to have this provided through udev, set
as something like:
    LIBINPUT_MOUSE_DPI="400 at 80" # dpi @ poll rate

over time, the udev hwdb could add those settings, or we ship them as
extra rules, or users configure them themselves. this is unfortunately a
rather nasty task given the amount of HW out there, but I really can't think
of any other way (short of heuristics which will fail in too many ways).

Any ideas on feasability or better approaches welcome.

Cheers,
   Peter