Re: Logitech Spring FF

["johann deneux" <johann.deneux@gmail.com>]

I'm forwarding this mail to linux-input, that's a better place for
this discussion.
Richard is working on adding support for spring force feedback effects
to the hid-lgff driver.

On 4/7/07, Richard Bolkey <rbolkey@cs.utexas.edu> wrote:
> johann deneux wrote:
> > Yes. It's possible to implement everything using a constant force
> > effect updated at regular intervals.
> > Are you working to extending the driver in the kernel, or are you
> > doing the work in user-space?
> Working off the driver in the kernel.  Can/should I do this in user
> space?  I also noticed with the latest kernels there is a ff-memless.c.

I'm not sure. Doing in the kernel would allow for a shorter update
cycle, I think. I had initially intended to do what you are doing in
the kernel, but I never actually finished the task.
One of the problem I remember encountering was related to computing
sine values when simulating a periodic effect. Is there a math lib
available in the kernel?

> Is that an attempt to do all effect calculations in a single module, and
> a driver like hid-lgff.c would just need to do the device recognitions?

I guess so, but you should check with the author.