Re: [Question: Drivers/input/evdev.c] What is the use of write function in evdev_fops?

[Peter Hutterer <peter.hutterer@who-t.net>]

On Fri, Aug 15, 2014 at 02:01:48AM +0530, Aniroop Mathur wrote:
[...]
> >> >>
> >> >>2 separate file descriptors like below ?
> >> >>int fd1 = open("/dev/uinput", O_RDWR);
> >> >>int fd2 = open("/dev/uinput", O_RDWR);
> >> >>
> >> >>But my reading data will still come in struct input_event as mentioned
> >> >>above.
> >> >>It has only time, type, code and value.
> >> >>So, how we can use bitmask here ?
> >> >>
> >> >>struct input_event {
> >> >>struct timeval time;
> >> >>__u16 type;
> >> >>__u16 code;
> >> >>__s32 value;
> >> >> };
> >> >
> >> > By opening 2 fds you'll end up creating 2 separate input devices with separate evdev nodes, etc, so you will not mix up input events.
> >> >
> >> > I think at this time you should just try actually using uinput and that should clear things for you.
> >> >
> >>
> >> Can you please explain what do you mean by separate evdev nodes ?
> >> Do you mean two separate evdev nodes for uinput ?
> >> But as we discussed before, there is only one node in case of uinput
> >> i.e. /dev/uinput.
> >
> > Uinput allows to creating input devices driven from userspace. You can
> > create as many separate input devices as you want by opening
> > /dev/uinput several times since it creates a device per file descriptor.
> > Each of these input devices will get evdev attached to it and will get
> > it's own /dev/input/eventX node created.
> >
> > Really, please try using uinput, it will clear a lot if things for you.
> > For example, see what http://www.freedesktop.org/wiki/Evemu/ does.
> >
> 
> 
> Thank you Mr. Torokhov for the discussion and answering my queries. :)
> I will try to explore more.

I recommend you look at libevdev if you're planning to use uinput. evemu
uses that now too and it makes a whole bunch of stuff easier and less likely
to go wrong.
http://freedesktop.org/wiki/Software/libevdev/

specifically:
http://www.freedesktop.org/software/libevdev/doc/1.2/group__uinput.html

Cheers,
   Peter