From mboxrd@z Thu Jan 1 00:00:00 1970 From: "johann deneux" Subject: Re: Logitech Spring FF Date: Sat, 7 Apr 2007 09:16:11 +0200 Message-ID: <38b3b7c0704070016m27deaa18hf818d21a080c7ba6@mail.gmail.com> References: <461117A0.80905@cs.utexas.edu> <4615D762.4090206@it.uu.se> <4616DC56.80301@cs.utexas.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4616DC56.80301@cs.utexas.edu> Content-Disposition: inline Sender: owner-linux-input@atrey.karlin.mff.cuni.cz List-Help: List-Owner: List-Post: List-Unsubscribe: To: Richard Bolkey , linux-input@atrey.karlin.mff.cuni.cz List-Id: linux-input@vger.kernel.org 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 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.