From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:50520 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753219Ab3AKMGF (ORCPT ); Fri, 11 Jan 2013 07:06:05 -0500 From: Laurent Pinchart To: Hans Verkuil Cc: linux-media@vger.kernel.org, Hans Verkuil Subject: Re: [REVIEW PATCHv1 1/2] DocBook: improve the error_idx field documentation. Date: Fri, 11 Jan 2013 13:07:45 +0100 Message-ID: <5369864.8TV5KUicak@avalon> In-Reply-To: <201301111248.19511.hverkuil@xs4all.nl> References: <1357560588-5263-1-git-send-email-hverkuil@xs4all.nl> <5589342.kjDUmhmVqU@avalon> <201301111248.19511.hverkuil@xs4all.nl> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Hans, On Friday 11 January 2013 12:48:19 Hans Verkuil wrote: > On Mon January 7 2013 20:56:07 Laurent Pinchart wrote: > > On Monday 07 January 2013 13:09:47 Hans Verkuil wrote: > > > From: Hans Verkuil > > > > > > The documentation of the error_idx field was incomplete and confusing. > > > This patch improves it. > > > > > > Signed-off-by: Hans Verkuil > > > --- [snip] > > I think some flexibility should still probably be left to drivers (and I'm > > not talking about UVC here), as some drivers might not be able to know > > that a control is write-only before trying to read it and getting an > > error. > > Well, if drivers don't know if a control is e.g. write-only until they try > it, then it can't be done during pre-validation anyway, so that's no > problem. Sure, but my point is that we don't want to enforce in the spec that those checks must always be done during pre-validation, otherwise drivers that can't do it will violate the spec. > The pre-validation should at minimum check whether ctrl_class is set up > correctly, whether all controls in the list actually exist, and check > against READ_ONLY or WRITE_ONLY (if known upfront). > > The v4l2-compliance tool will test those minimum checks. > > The control framework will also check whether the GRABBED flag is set for > a control and if the new value of a control is valid. -- Regards, Laurent Pinchart