From mboxrd@z Thu Jan 1 00:00:00 1970 From: simon@mungewell.org Subject: Rewriting wheels HID descriptor for complete functionality Date: Wed, 1 Dec 2010 13:23:15 -0500 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from host171.canaca.com ([67.55.55.225]:46265 "EHLO host171.canaca.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751475Ab0LASXR (ORCPT ); Wed, 1 Dec 2010 13:23:17 -0500 Received: from localhost ([127.0.0.1] helo=host171.canaca.com) by host171.canaca.com with esmtpa (Exim 4.69) (envelope-from ) id 1PNrKl-0001Ui-MW for linux-input@vger.kernel.org; Wed, 01 Dec 2010 13:23:15 -0500 Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: linux-input@vger.kernel.org I am working on a driver for a Logitech gaming wheel where the HID descriptor presents a 'joystick' with X and Y axis, the Y is a combined acc/brake value even though the wheel has separate paddles for each. There are 'vendor defined' variables for both the acc/brake within the HID descriptor, but these are not (by Linux) tied to their function. On the Windows, the specialised Logitech driver gives the option to use either combined or separate acc/brake. I am considering re-writing the HID descriptor to expose these separate values as 'proper' axis, as they would provide both better resolution and better functionality (ie. left foot braking). Q1. Is this an acceptable thing to do? Q2. In the case where there is significant change to the HID descriptor, is it OK to just re-write the whole block (rather than patch/swap a couple of bytes)? Q3. In re-writing descriptor for the combined acc/brake. Is there a particular 'variable' I should change it to (X, Y and Z would already be used), or should I just make it 'vendor defined'? Thanks in advance, Simon (aka Mungewell)