Hello,
if I plug my Xbox 360 controller and run fftest on it, then the
following force feedback modes are listed as supported:
| Force feedback effects types: Periodic, Rumble, Gain,
| Force feedback periodic effects: Square, Triangle, Sine,
If I have a look at the driver itself, then it actually only supports
FF_RUMBLE:
https://github.com/torvalds/linux/blob/master/drivers/input/joystick/xpad.c#L1054
https://github.com/torvalds/linux/blob/master/drivers/input/joystick/xpad.c#L966
So somewhere in the kernel source there has to be some kind of built-in
force feedback effect emulation...
If I do the same in an uinput driver (only report "FF_RUMBLE" as being
supported), then fftest only shows this one effect to be supported by
the device. The "kernel side emulation" does not kick in...
The kernel documentation
(https://www.kernel.org/doc/Documentation/input/ff.txt) says:
| Note: In most cases you should use FF_PERIODIC instead of FF_RUMBLE.
| All devices that support FF_RUMBLE support FF_PERIODIC (square,
| triangle, sine) and the other way around.
But what could be the mistake, which allowed me to create a device
driver which actually only supports FF_RUMBLE? Are there any special
driver parameters that have to be present, so the kernel side emulation
gets active?
Thanks in advance.
Best regards,
Manuel
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