Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760499AbXFDS4i (ORCPT ); Mon, 4 Jun 2007 14:56:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758176AbXFDS4a (ORCPT ); Mon, 4 Jun 2007 14:56:30 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:57761 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757139AbXFDS43 (ORCPT ); Mon, 4 Jun 2007 14:56:29 -0400 Subject: Re: [PATCH 1/1] V4L: stk11xx, add a new webcam driver From: Mauro Carvalho Chehab To: Thierry Merle Cc: video4linux-list@redhat.com, linux-kernel@vger.kernel.org, Andrew Morton , Jiri Slaby In-Reply-To: <466131CB.20301@free.fr> References: <2172422218943432279@wsc.cz> <1180364420.21547.160.camel@localhost> <1180378677.21547.189.camel@localhost> <1180383071.21547.230.camel@localhost> <465B49EB.4080204@free.fr> <465BBAFB.30906@free.fr> <1180448712.21547.314.camel@localhost> <465C7920.2080203@free.fr> <1180467116.9509.73.camel@localhost> <465F3361.106@free.fr> <1180739401.3904.50.camel@localhost> <466131CB.20301@free.fr> Content-Type: text/plain; charset=utf-8 Date: Mon, 04 Jun 2007 15:55:04 -0300 Message-Id: <1180983304.10894.19.camel@gaivota> Mime-Version: 1.0 X-Mailer: Evolution 2.10.0-5mdv2007.1 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 41 Em Sáb, 2007-06-02 às 11:00 +0200, Thierry Merle escreveu: > > Mauro Carvalho Chehab a écrit : > >>> This seems to be an interesting approach. > >>> > >>> > >>> > >> Interesting but impossible to do for ioctl calls. > >> When the application does a ioctl(fd_of_mnt_video0,VIDIOC_G_FMT,&arg) > >> for example, there is no way for the userspace helper to catch this ioctl. > >> The application could only open/read from the userspace helper's file > >> /mnt/video0. > >> ioctl would still have to be done on the kernel device driver. > >> I thought also about a /proc interface for decompression algorithms (a > >> helper would listen on a /proc file and write on another /proc file) but > >> /proc is not designed for that kind of thing. > >> A separate library seems to be the simplest solution. > >> > > > > There are some ways for this to work. For example, you may create a > > helper device for the daemon driver to bind, even requiring it to have > > root permission. > > > > > Right, but I am afraid that complex userspace/kernelspace context > changes breaks performance. Yes, there's a risk. > Nevertheless, I will start to specify the framework. > The helper daemon would link to the v4l2-apps/lib. Ok, thanks! -- Cheers, Mauro - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/