help wanted: Pi3 video works w/ upstream build, fails with Debian build

[Jonathan Dowland <jmtd@debian.org>]

Hi, I'm emailing to seek some advice. In short, when I build a kernel
using the Debian package sources, adding CONFIG_FB_SIMPLE and
PROC_IKCONFIG, but using the upstream build process from that point
onwards, the resulting kernel has working video on a Raspberry Pi 3.

If I try to do the same using the Debian kernel build process as
outlined in the handbook, then the resulting kernel does NOT have
working video on the same hardware.

I've really no idea why there is a difference.

We've had independent confirmation that building the upstream sources
with CONFIG_FB_SIMPLE results in working video.

I've put up my working kernel here (that's the debian kernel sources
with the patches applied etc but built with the upstream build process)
   https://jmtd.net/tmp/pi3/vmlinuz-4.11.6
   modules: https://jmtd.net/tmp/pi3/4.11.6.tar.xz (46M)
   (there's an initramfs in there too)

I've also put up the not-working .debs (https://jmtd.net/tmp/pi3/)

And a dmesg output from running the .debs which seems to include some
kind of backtrace which is probably relevant.

   https://jmtd.net/tmp/pi3/dmesg.txt

--

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⣾⠁⢠⠒⠀⣿⡁ Jonathan Dowland
⢿⡄⠘⠷⠚⠋⠀ https://jmtd.net
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