On Thu, Jul 04, 2013 at 11:40:17AM +0200, Sebastian Hesselbarth wrote: > On 07/04/13 11:23, Sascha Hauer wrote: > > > >With this you can describe the whole graph of devices you have in the > >devicetree. The examples in this file have a path from a camera sensor > >via a MIPI converter to a capture interface. > > > >The difference to a supernode is that this approach describes the data > >flow in the devicetree so that we can iterate over it to find links > >between source and sink rather than relying on a list of subdevices to > >be completed. > > Agree. But that is not that different from linux,video-external-encoder > property I made up, except that the name is different. > > And, I still see no way with that source/sink linking _alone_ how to > tell that either lcd0 and lcd1 act as a _single_ video card or lcd0 and > lcd1 are used in a _two_ video card setup. > > There is no single device node on Dove that would sufficiently act as > the top node for a working video card on all boards. And there is no > framebuffer node to link each of the lcd0/1 nodes to. > > That is what the super-node is for, form a virtual device called > video card to act as a container for all those SoC devices that are > not sufficient for a working video setup on their own. > > If lcd0 needs that hdmi-transmitter you link it to the lcd0 node - > not the super-node. If lcd0 needs some pll clock you link it to the > lcd0 node - again not the super-node. > > The super-node(s) just connects all SoC devices that shall be part of > your board-specific video card(s) - for Dove that is any combination of > lcd0, lcd0, dcon and video memory allocation. So with the supernode approach you would have one/two supernodes and with a v4l2 approach you would have either one graph containing lcd0 and lcd1 or to graphs (without a connection in between). Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
