On Thu, Jul 07, 2005 at 05:20:59PM +0300, Anssi Hannula wrote: > Vojtech Pavlik wrote: > >On Fri, Apr 08, 2005 at 08:29:52PM +0300, Anssi Hannula wrote: > > > >>This patch adds Force Feedback interface to joydev. I felt this > >>necessary because games usually don't run as root while evdev usually > >>can't be read or written by anyone else. Patch is against 2.6.12-rc2. If > >>there is a reason this can't be applied or needs modifications, please > >>say it :) > > > >Modern distros usually chown() the event devices to the user logged on > >the console, so this shouldn't be a problem. Anyway, I'm not opposed to > >adding the ioctl()s, but you should also add 64-bit compatible versions > >of them. > > > > Well, with Mandriva 10.2 that happens only with jsX. > > But I think we should not apply (with or without 64-bit) the patch (not > yet, anyway), as I'm (slowly) working on restructuring the kernel FF > interface and developing a user space library (and writing a generic HID > PID FF-driver).
That sounds interesting. However - I don't know of many devices that'd be PID compliant except for the MS SideWinder ForceFeedback Pro 2. All the Logitechs, as far as I know don't implement full PID. > As a matter of fact, I have two (lengthy) questions: > > 1. What would be the best way to decide when to delete the effects of a > specific process from the device? Currently it is done when flush is > called. However, if one process holds multiple fd's to the interface > (for example input fd through some gaming-input library and FF fd with > the FF library), when any of these closes, all effects are deleted. Good > way to overcome this would be fd-specific effects instead of > process-specific, but I've got no idea how that would be done. One > possible way would be introducing a new device file solely for the FF > (so there would be no reason to hold multiple fd's to this file by the > same process), but would that be overkill? I don't think that the fact that when a process holds the device open twice, the first close flushes the FF effects is that big a problem. > 2. Many simpler devices do not have any effect memory, for example there > is just one HID report that is used to apply an effect and stop it. They > could share very much of their timing code (they have effect memories > and timers implemented in software in the kernel). These would also need > software handling of envelopes, which is currently not implemented at > all (also some effects could possibly be software emulated). So, should > these be implemented by the kernel at all or should they implemented in > the userspace library? Probably both. The timing sensitive stuff in the kernel, all the rest in an userspace library. -- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/