From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60580 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752121Ab0AZM3G (ORCPT ); Tue, 26 Jan 2010 07:29:06 -0500 Message-ID: <4B5EE01F.2080702@redhat.com> Date: Tue, 26 Jan 2010 13:29:19 +0100 From: Hans de Goede MIME-Version: 1.0 To: =?UTF-8?B?TsOpbWV0aCBNw6FydG9u?= CC: Jean-Francois Moine , Thomas Kaiser , V4L Mailing List Subject: Re: [RFC, PATCH] gspca pac7302: propagate footer to userspace References: <4B5C8172.1090306@freemail.hu> In-Reply-To: <4B5C8172.1090306@freemail.hu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Németh, On 01/24/2010 06:20 PM, Németh Márton wrote: > Hi, > > I'm dealing with Labtec Webcam 2200 and I found that the pac7302 driver does not > forward the image footer information to userspace. This footer contains some information > which might be interesting to the userspace. What exactly this footer means is > not clear as of this writing, but it is easier to analyze the data in > userspace than in kernel space. > > I modified the sd_pkt_scan() in order the footer is transfered to the userspace together > with the image. This, however, breaks the image decoding in libv4lconvert. This is > can be easily solved by passing the image buffer to v4lconvert_convert() truncated by > 0x4f bytes. > > What do you think the right way would be to transfer image footer to userspace? I agree that in retrospect sending the footer to userspace is a good idea, but see below. > Is it necessary to add a new V4L2_PIX_FMT_* format in order not to brake userspace > programs? > Yes that is the only sensible way I see to do this, which IMHO is a too high price to pay for just getting this info out of the kernel while we are not doing anything with it. Now if we actually find a good use for this in userspace, then I think we can do this, but until then I think you need to do this with a local patch. Regards, Hans