From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dmitry Torokhov" Subject: Re: [linux-usb-devel] detecting when keys are being pressed on a keyboard Date: Mon, 24 Sep 2007 09:45:46 -0400 Message-ID: References: <200709211033.09698.oliver@neukum.org> <200709241256.05300.oliver@neukum.org> <200709241539.19610.oliver@neukum.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200709241539.19610.oliver@neukum.org> Content-Disposition: inline Sender: owner-linux-input@atrey.karlin.mff.cuni.cz List-Help: List-Owner: List-Post: List-Unsubscribe: To: Oliver Neukum Cc: linux-usb-devel@lists.sourceforge.net, linux-input@atrey.karlin.mff.cuni.cz List-Id: linux-input@vger.kernel.org On 9/24/07, Oliver Neukum wrote: > Am Montag 24 September 2007 schrieb Dmitry Torokhov: > > Hi Oliver, > > > > On 9/24/07, Oliver Neukum 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