Which of the FF_* features does evtest report as supported?

Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x46d product 0xc21f version 0x305
Input device name: "Logitech Gamepad F710"
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
Event code 304 (BTN_SOUTH)
Event code 305 (BTN_EAST)
Event code 307 (BTN_NORTH)
Event code 308 (BTN_WEST)
Event code 310 (BTN_TL)
Event code 311 (BTN_TR)
Event code 314 (BTN_SELECT)
Event code 315 (BTN_START)
Event code 316 (BTN_MODE)
Event code 317 (BTN_THUMBL)
Event code 318 (BTN_THUMBR)
Event type 3 (EV_ABS)
Event code 0 (ABS_X)
Value 128
Min -32768
Max 32767
Fuzz 16
Flat 128
Event code 1 (ABS_Y)
Value -129
Min -32768
Max 32767
Fuzz 16
Flat 128
Event code 2 (ABS_Z)
Value 0
Min 0
Max 255
Event code 3 (ABS_RX)
Value 128
Min -32768
Max 32767
Fuzz 16
Flat 128
Event code 4 (ABS_RY)
Value -129
Min -32768
Max 32767
Fuzz 16
Flat 128
Event code 5 (ABS_RZ)
Value 0
Min 0
Max 255
Event code 16 (ABS_HAT0X)
Value 0
Min -1
Max 1
Event code 17 (ABS_HAT0Y)
Value 0
Min -1
Max 1
Event type 21 (EV_FF)
Event code 80 (FF_RUMBLE)
Event code 81 (FF_PERIODIC)
Event code 88 (FF_SQUARE)
Event code 89 (FF_TRIANGLE)
Event code 90 (FF_SINE)
Event code 96 (FF_GAIN)

Only missing the two SAW options, which I don't expect anyone to use on a gamepad. Where is it not working?

basically any steam game I have.
ANd now there's a tricky part - sometimes and only in some games (for example Broforce, Shadow of Mordor) it starts to work. Only after some fiddling with various stuff - switching on/off big picture mode, doing sudo rmmod xpad and reconnecting the pad... Can't find a pattern there.
BUt still there are games like Fez where I never seen it working.

I'm rather clueless. So any suggestions on drivers / system settings I could try would be welcome.

Are you using a buggy version of the xpad drivers? There have been issues with force feedback which have been fixed in the latest release. The fixes have been backported to Ubuntu 16.04, if you use that distribution.

I have also 2x F710 Logitech wireless but I dont see any problem with rumble.
I mean if the game supports rumble is working fine.

Can you tell me a game to test it?

don't know - how can I check that / which ones are good, which bad (and no I don't use Ubuntu) :) ?

Also I've been able to cut random working / not working behaviour in Broforce and Shadow of Mordor ... by using batteries instead of recharchable units (facepalm - the rumble behaves badly even on a freshly recharged unit - guess it may be something related to lower voltage on those)...
Still no joy in a couple of titles like Fez.

I am not using Ubuntu , I am using Manjaro and everything is working fine especially Broforce is very sensitive :)
Fez is also working but not too much rumble on that game just the big explosion at start and when I fall down from something.
(Didnt play Fez much just boring game :P)

I am using Kernel 4.7

thx for the offer wolfyrion - I'm slowly getting the things going :) . Will post if I encounter any more issues with f710.

I had a quick peek at the driver. It runs fully over the code of the xbox360 controller. This also means that only FF_RUMBLE is implemented by the driver. The other FF_ effects are emulated through FF_RUMBLE. This may affect things if games use the periodic effects (which is actually recommended).

Also, did you verify that both the weak and the strong rumble motor operate separately? If one is not working, you could miss out on things as well.