WIP: IPU and HDMI drivers for i.MX6

[Oleksandr Tymoshenko]

> On Jul 20, 2015, at 5:07 AM, Ulrich Grey <usenet at ulrich-grey.de> wrote:
> 
> Hello,
> 
> I am running
> 
> FreeBSD wqtest 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r285652M: Sat Jul 18
> 01:43:03 UTC 2015     gwgpi at wqtest-hf:/usr/obj/usr/src/sys/IMX6  arm armv6hf
> 
> on a Wandboard-Quad. I have built the image with HDMI-patch using
> /usr/src/release/release.sh -c arm/Wandboard.conf
> on the Wandboard itself (a armv6hf system).
> 
> To boot I had to copy ubldr from a armv6 image to the fat partition.
> I don't know whether this is important in this context. Images without HDMI-patch are
> booting successfully.
> 
> During boot I got a grapical u-boot logo, then the screen jitters and is black.
> I have used an old EIZO Monitor and a Philips TV set. Both don't work.

It seems to be the same problem Mikaël has: two IPUs active. Also it's not
clear why reading EDID fails, so I added some more debug output

New patch:
https://people.freebsd.org/~gonzo/arm/patches/imx6-ipu-hdmi-20150720.diff