Re: uinput: How to use force feedback?

[Manuel Reimer <Manuel.Spam@nurfuerspam.de>]

Hello,

I just want to add here, that I found the reason for this problem.

It is required that the ff_effects_max field of the uinput_user_dev 
struct is set. Without doing this everything just hangs...

Best regards,

Manuel

On 02/05/2016 04:54 PM, Manuel Reimer wrote:
> On 01/17/2016 04:46 PM, Elias Vanderstuyft wrote:
>> Concerning this,
>> the following may give you an example how to read incoming FF events
>> on uinput:
>> https://github.com/xboxdrv/xboxdrv/blob/8e9fb6b40df568d4e4af63e80518366ee4aa5fd3/src/linux_uinput.cpp#L341
>>
>
> Tried that and I'm pretty close to giving up...
>
> I've added the following to my uinput init function:
>
>    // Set up force feedback parameters
>    ret = ioctl(fd, UI_SET_EVBIT, EV_FF);
>
>    ret = ioctl(fd, UI_SET_FFBIT, FF_PERIODIC);
>    ret = ioctl(fd, UI_SET_FFBIT, FF_RUMBLE);
>    ret = ioctl(fd, UI_SET_FFBIT, FF_GAIN);
>    ret = ioctl(fd, UI_SET_FFBIT, FF_SQUARE);
>    ret = ioctl(fd, UI_SET_FFBIT, FF_TRIANGLE);
>    ret = ioctl(fd, UI_SET_FFBIT, FF_SINE);
>
>  From my device handling thread, I'm starting a separate thread to
> handle the opposite direction of communication. Plan is to do blocking
> read from the open uinput device. I open the device with O_RDWR to be
> able to read and write. The "rumble thread" starts with:
>
>    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
>    pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
>
>    struct input_event event;
>
>    while (1) {
>      ssize_t n = read(args->fduinput, &event, sizeof(event));
>      printf("n: %d\n", n);
>
> Everything beyond this never executes. The read blocks forever.
>
> And even worse: If the read blocks, my "driver", and all programs
> connected to my input device, are deadlocked. No chance to kill them.
>
> And to be honest: After three hours of debugging I'm kind of sick of
> rebooting my machine over and over again.
>
> Any chance to get some hint?
>
> Thanks in advance
>
> Manuel
>
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