From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from ti-out-0910.google.com ([209.85.142.187]:46043 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753222AbZBLWpC (ORCPT ); Thu, 12 Feb 2009 17:45:02 -0500 Received: by ti-out-0910.google.com with SMTP id d10so613394tib.23 for ; Thu, 12 Feb 2009 14:45:00 -0800 (PST) Message-ID: <4994A667.2000909@gmail.com> Date: Fri, 13 Feb 2009 09:44:55 +1100 From: gilles MIME-Version: 1.0 To: linux-media@vger.kernel.org Subject: Comments on V4L controls Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi everyone, Sorry for double posting, but I originally sent this to the old mailing list. Here it is: I have a couple of comments / suggestions regarding the part on controls of the V4L2 api: Some controls, such as pan relative and tilt relative are write-only, and reading their value makes little sense. Yet, there is no way of knowing about this, but to try and read a value and be greeted with EINVAL or similar. There is already a read-only flag (V4L2_CTRL_FLAG_READ_ONLY) in struct v4l2_query. Does it make sense to add another one for write-only controls ? The extended controls Pan / Tilt reset are defined in the API as boolean controls. Shouldnt these be defined as buttons instead, as they dont really hold a state (enabled/disabled) ? Comments are welcome. Cheers, Gilles