From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anssi Hannula Subject: Re: Logitech Spring FF Date: Sat, 07 Apr 2007 18:06:58 +0300 Message-ID: <4617B392.4010704@gmail.com> References: <461117A0.80905@cs.utexas.edu> <4615D762.4090206@it.uu.se> <4616DC56.80301@cs.utexas.edu> <38b3b7c0704070016m27deaa18hf818d21a080c7ba6@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <38b3b7c0704070016m27deaa18hf818d21a080c7ba6@mail.gmail.com> Sender: owner-linux-input@atrey.karlin.mff.cuni.cz List-Help: List-Owner: List-Post: List-Unsubscribe: To: johann deneux Cc: Richard Bolkey , linux-input@atrey.karlin.mff.cuni.cz List-Id: linux-input@vger.kernel.org johann deneux wrote: > 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. The correct way to implement this is to do it in ff-memless.c, and it already has the framework to do effect conversions. > 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? There is your fixp-arith.h in /drivers/input and apparently some random math functions in /lib. (and I think the fixp-arith.h should really be in /lib as well) >> 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. > Yes, it is. -- Anssi Hannula