Hi Benjamin, > I have been reported recently a problem with the Sixaxis controller > (http://www.spinics.net/lists/linux-input/msg28098.html). > The root of the problem comes from hid-input, which maps unknown axis to > ABS_MISC. However, when an event code is already in use, hid-input uses the one > after, leading to uses of ABS_MISC + N, where N is the number of unknown axis. Yes, and clearly we should not do that. :-) > We are encountering a problem with the multitouch protocol here because if a > device has more than 7 unknown axis (which is the case for the PS3 Sixaxis > controller), then the unknown axis get maps to ABS_MT_SLOT and beyond. > > This infers two problems: > - the axis currently mapped on ABS_MT_SLOT is a special case in the kernel, > and it is not updated > - the axis after ABS_MT_SLOT are not filtered anymore, as the kernel things > the device is using a multitouch protocol A. The problem is generic, and ABS_MT_SLOT just happens to be the first value that the hid logic hits. When sevenaxis comes out, we have to do this all over again. > The patch 0001 solves the first problem, whereas the patches 0002 and 0003 > fix the second. Bonus point: the userspace is now correctly notified that one of > the multitouch protocols is in used, so it does not have to rely on bad designed > heuristics. The bad heuristics are lines 918 and onwards in hid-input.c. I am sure we can come up with a way to allocate those axes in a much less fragile way. Thanks, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
