From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Krivoschekov Subject: Re: [PATCH 2/4 v4] i.MX31: Image Processing Unit DMA and IRQ drivers Date: Tue, 23 Dec 2008 13:09:10 +0300 Message-ID: <4950B8C6.30309@gmail.com> References: <20081218225834.GJ20756@pengutronix.de> <20081222183753.GD1614@pengutronix.de> <20081222200337.GD9472@pengutronix.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081222200337.GD9472@pengutronix.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Robert Schwebel Cc: Guennadi Liakhovetski , linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com, linux-arm-kernel@lists.arm.linux.org.uk, Dan Williams Robert Schwebel wrote: > On Mon, Dec 22, 2008 at 07:37:53PM +0100, Sascha Hauer wrote: >> Another thing is the overlay framebuffer. I think it's mainly useful >> to display video streams. > > Right. The idea is that you can push a video stream into /dev/fb1 (for > example by using the gstreamer fbdev sink) while displaying widgets from > a GUI toolkit on /dev/fb0. > >> Maybe it's better to implement this as a v4l device as unlike the >> framebuffer API the v4l API is designed to handle different image >> buffers. > > Huh? v4l is image-frames-to-userspace, not vice versa. > ...and vice versa too, v4l2 is not about input devices only but it is also related to output devices, v4l2 spec even has a special chapter dedicated to overlays [1]. Moreover, you can find such a driver within Freescale's BSP [2]. Another example is Omap's videoout driver [3]. Dmitry [1]http://v4l2spec.bytesex.org/spec-single/v4l2.html#OVERLAY [2]http://opensource.freescale.com/git?p=linux-2.6-mx.git;a=blob;f=drivers/media/video/mxc/output/mxc_v4l2_output.c;h=309700bb9d1f3b3f9dcac8a48a16d0775b8ed93a;hb=refs/heads/bsp-imx31ads-rel5 [3]http://git.omapzoom.org/?p=omapkernel.git;a=blob;f=drivers/media/video/omap/omap24xxvout.c;h=25ac1319bae58751cd1a543aa0f320159e10a475;hb=HEAD