Re: [linux-usb-devel] detecting when keys are being pressed on a keyboard

["Dmitry Torokhov" <dmitry.torokhov@gmail.com>]

On 9/24/07, Oliver Neukum <oliver@neukum.org> wrote:
> Am Montag 24 September 2007 schrieb Dmitry Torokhov:
> > Hi Oliver,
> >
> > On 9/24/07, Oliver Neukum <oliver@neukum.org> wrote:
> > > Am Freitag 21 September 2007 schrieb Jiri Kosina:
>
> > > > Hi Oliver,
> > > >
> > > > HID doesn't keep any permanent state by itself. If you want to know
> > > > whether a given key is currently pressed or not, you'd have to inspect the
> > > > bitfields inside input_dev*, I am afraid.
> > >
> > > I see no way to do this without a race condition. The field isn't locked
> > > as far as I can tell.
> >
> > You can take input_dev->event_lock to stop event from propagating
> > through input core while you are evaluating the bits. Input lcoking
> > changes are im -mm and will be merged into 2.6.24.
>
> Hi Dmitry,
>
> I was thinking about a second approach. As all keypresses run through
> the interrupt handlers of the hid driver, how about checking the bit field
> in the interrupt handler after calling hid_input_report() ?
>

That should work as well I think.

-- 
Dmitry