Unable to boot mainline on snow chromebook since 3.15

[Doug Anderson]

Hi,

On Sun, Sep 7, 2014 at 8:52 AM, Tomasz Figa <tomasz.figa at gmail.com> wrote:
> So I believe we've got a process issue here. If you don't have normal
> support for display hardware, but you want to keep the display
> operational thanks to bootloader already initializing it, you should not
> add anything to the kernel which breaks it, until full support comes in.
>
> This means that respective regulators should be either always-on or not
> listed at all (I'd favor the former) and respective clocks either
> somehow enabled at boot-up or completely ignored, including all their
> parents capable of being gated.

It seems slightly broken to hack the device tree in this way.  I'll be
the first to admit that I often list regulators as "always-on" during
bringup when not everything is done, and I guess it's not that
different.  ...but given everything going on upstream (and people
working on Suspend/Resume, DRM, etc) it seems like it might be a bit
of a pain.  ...but if that's what everyone agrees on, I won't disagree
too strongly.

One (ugly?) solution would be to add a feature to your bootloader to
modify the device tree to mark regulators as "always-on".  Since the
booloader gets to touch the device tree and the bootloader is involved
in communicating into about SimpleFB, it kinda makes sense.