From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anssi Hannula Subject: Re: FF layer restrictions [Was: [PATCH 1/1] Input: add sensable phantom driver] Date: Wed, 14 Mar 2007 20:04:32 +0200 Message-ID: <45F83930.4060401@gmail.com> References: <2460126662758025813@fi.muni.cz> <45EEEAA3.50009@gmail.com> <4af2d03a0703130919nb4893b1ja9ec795dcf4bf53c@mail.gmail.com> <38b3b7c0703131450v2646e63fj2be4b9dda7f928c0@mail.gmail.com> <45F722CE.9000602@gmail.com> <45F82626.8000108@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <45F82626.8000108@gmail.com> Sender: owner-linux-input@atrey.karlin.mff.cuni.cz List-Help: List-Owner: List-Post: List-Unsubscribe: To: Jiri Slaby Cc: Dmitry Torokhov , johann deneux , Linux kernel mailing list , linux-input@atrey.karlin.mff.cuni.cz List-Id: linux-input@vger.kernel.org Jiri Slaby wrote: > Dmitry Torokhov napsal(a): >> On 3/13/07, Jiri Slaby wrote: >>> Why did you remove all Cced people? Anyway I filtered some of them out >>> >>> johann deneux napsal(a): >>>> You are right, the direction in ff_effect is meant to be an angle. >>>> A dirty solution would be to use the 16 bits as two 8-bits angles. Or >>> That would be a problem as I need 3x 16bits. Interesting. What kind of device is that? i.e. what is the third direction value? >>>> maybe we should change the API. I don't think there are many >>>> applications using force feedback yet, so maybe that should be ok? >>>> >>>> If we change the API, we should remove the assumption that a device has >>>> at most two axes to render effects. We could for instance have a >>>> magnitude argument for each axis which is capable of rendering effects. >>>> That might be necessary even for more common gaming devices like racing >>>> wheels: One can think pedals could also be capable of force feedback >>>> some day, not just the steering wheel. >>> I can do that, but in that case, I need to know how people (especially >>> those >>> input one) want me to do... >>> >> Since we have no idea how many programs (if any) are using force >> feedback interface I would be wary of changing existing effcets and > > I definitely agree. > >> rather add new set of 3D effects. > > I was thinking about having "raw" (e.g. FF_RAW) effect, which would be only > X "axes"/entries of u32, where X is about 10 for future use and simply > posting these values further to HW (maybe after clamping or driver specific > processing) from this array. This seems to be augmentation of FF_CONSTANT > but the fact, it doesn't compute forces from direction. I don't like the idea of a driver-specific "raw" effect, I'd rather add real effect types. > Also yet another one such as FF_VECTOR or FF_3D could be considered as one > posibility, but it's still the same -- to have no more than 3 entries to > pass forces... > >> Do we have any idea if there any users of FF out there? > > At least me :). I'm using it for wheel and joystick in modules for locally > developped multiplatform virtual reality system. Wine and BZflag come to mind, though I think the support is quite limited in both. -- Anssi Hannula