quoted

Regarding the question of emulated vs. real effects, can we extend the
API
so that applications can know which effects are really supported, and
enable/disable emulation somehow?

I suppose that a few extra flags (FF_PERIODIC_EMULATED etc.) defined in
"uapi/linux/input.h" should suffice.

The only problem is that we probably want to maintain backward
compatibility so that older apps still see 'PERIODIC' (even though it is
emulated).
--
#define FF_RUMBLE	0x50
#define FF_PERIODIC	0x51
#define FF_CONSTANT	0x52
#define FF_SPRING	0x53
#define FF_FRICTION	0x54
#define FF_DAMPER	0x55
#define FF_INERTIA	0x56
#define FF_RAMP		0x57
--

Do we therefore have to list extra items in our capabilities?
--
static const signed short lg4ff_wheel_effects[] = {
	FF_CONSTANT,
	FF_PERIODIC,
	FF_PERIODIC_NOT_EMULATED,
	FF_AUTOCENTER,
	-1
};
--

Simon