4.6.0-11.13 from ckt PPA fails to boot on X-Gene

[dann frazier]

The 4.6.0-11.13 kernel currently in the ckt ppa fails to boot on X-Gene systems, such as the Mustang board. Even with earlycon enabled, there is no output from the kernel on the console (see the attached console log). The same kernel boots fine on other arm64 systems - this appears to be X-Gene specific.

A defconfig build boots fine on the same system - so I bisected down the relevant config change. The results were unexpected, but CONFIG_ARCH_ROCKCHIP=y appears to be required for X-Gene to boot.

Digging down deeper, I found that the following 2 specific configs are required (I had to do hack Kconfigs to make them selectable independent of CONFIG_ARCH_ROCKCHIP):

CONFIG_PINCTRL_ROCKCHIP=y
CONFIG_ROCKCHIP_TIMER=y

Both of which are drivers that do not bind to devices on X-Gene.

[dann frazier (dannf)]

This isn't an issue w/ current git (4.8-rc3+), so I bisected in hunt for the "fix". I hit this commit:

commit d94ba9e7d8d5c821d0442f13b30b0140c1109c38
Merge: 1c88e19 9573e79
Author: Linus Torvalds <email address hidden>
Date: Thu Jul 28 17:06:51 2016 -0700

    Merge tag 'pinctrl-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl

It's a merge commit w/ no conflict resolution. So, pinctrl seems to be a common theme here - but the root cause is still not clear.

[Andy Whitcroft (apw)]

This bug was nominated against a series that is no longer supported, ie yakkety. The bug task representing the yakkety nomination is being closed as Won't Fix.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.