Re: [PATCH 2/4 v4] i.MX31: Image Processing Unit DMA and IRQ drivers

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Dmitry Krivoschekov <dmitry.krivoschekov@gmail.com>
Cc: Robert Schwebel <r.schwebel@pengutronix.de>,
	Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
	linux-kernel@vger.kernel.org,
	linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com,
	linux-arm-kernel@lists.arm.linux.org.uk,
	Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH 2/4 v4] i.MX31: Image Processing Unit DMA and IRQ drivers
Date: Tue, 23 Dec 2008 11:52:46 +0100	[thread overview]
Message-ID: <20081223105246.GF1614@pengutronix.de> (raw)
In-Reply-To: <4950B8C6.30309@gmail.com>

On Tue, Dec 23, 2008 at 01:09:10PM +0300, Dmitry Krivoschekov wrote:
> 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].

Are you aware of any application making use of this feature?

Sascha

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