Re: uinput: ioctls for UI_BEGIN_FF_UPLOAD fails (returns -1). How to debug?

2016-03-28 10:53 GMT+02:00 Manuel Reimer [off-list ref]:

On 03/27/2016 09:11 PM, Clément VUCHENER wrote:

quoted

Check the value of errno just after the failed call (and use strerror
to get a nice error message).

See the following output of my test program


UI_FF_UPLOAD start
UI_FF_UPLOAD middle
first ioctl failed -1 Inappropriate ioctl for device
second ioctl failed -1 Inappropriate ioctl for device
UI_FF_UPLOAD end

quoted

You also need to check the event code, it must be UI_FF_UPLOAD.

    else if (event.type == EV_UINPUT) {
      printf("EV_UINPUT %d\n", event.code);
      if (event.code == UI_FF_UPLOAD) {
        printf("UI_FF_UPLOAD start\n");
        struct uinput_ff_upload upload;
        memset(&upload, 0, sizeof(upload));

        upload.request_id = event.value;

        printf("UI_FF_UPLOAD middle\n");mulitple
        int ret;
        ret = ioctl(args->fduinput, UI_BEGIN_FF_UPLOAD, &upload);
        if (ret < 0) {
          printf("first ioctl failed %d %s\n", ret, strerror(errno));
        }

        // Remember ID and motor values for playback
        if (upload.effect.type == FF_RUMBLE) {
          effect_id = upload.effect.id;
          strong = upload.effect.u.rumble.strong_magnitude;
          weak = upload.effect.u.rumble.weak_magnitude;
          printf("Effect uploaded\n");
        }

        ret = ioctl(args->fduinput, UI_END_FF_UPLOAD, &upload);
        if (ret < 0) {
          printf("second ioctl failed %d %s\n", ret, strerror(errno));
        }
        printf("UI_FF_UPLOAD end\n");
      }
      else if (event.code == UI_FF_ERASE) {
        struct uinput_ff_erase erase;
        memset(&erase, 0, sizeof(erase));

        erase.request_id = event.value;

        // Doesn't make sense to actually erase something...
        ioctl(args->fduinput, UI_BEGIN_FF_ERASE, &erase);
        ioctl(args->fduinput, UI_END_FF_ERASE, &erase);
        printf("Event erased\n");
      }
    }

This looks fine to me (maybe you should make sure upload.retval is
correctly set before calling UI_END_FF_UPLOAD, but that is not related
to your problem).

I report that my device only supports one effect at once. My idea was that I
maybe try to get ff-memless connected to uinput at a later time to make it
emulate the common "memless configuration" used by the kernel and operate my
one-effect-rumble-only device.

The above code works well as long as nothing was sent out to the open uinput
file descriptor.

As soon as I press a button on my USB input device, it "wakes up" and sends
out information even if no button is pressed. This information is also
forwarded to uinput, so from this point on there is a regular information
stream from my code to the uinput module.

Maybe I have to add that I run dual-threaded. The above code is from my
"reception thread". The sending runs on a separate "sending thread".

Did I currently find out that uinput is not multithread-safe?

I am using uinput with multiple threads without problems (one in a
reading loop like yours, others writing events). You must be doing
something wrong with that file descriptor in that other thread.

Manuel

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