Re: Unable to boot mainline on snow chromebook since 3.15

[Mark Brown <broonie@kernel.org>]

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On Mon, Sep 08, 2014 at 01:20:11PM +0100, Grant Likely wrote:
> On Mon, Sep 8, 2014 at 12:21 PM, Will Deacon <will.deacon@arm.com> wrote:

> > Whilst I'm sympathetic to people working to enable DRM, I think this is
> > the right solution to the problem. The transition from simplefb to DRM
> > shouldn't break display for a bunch of kernel revisions whilst the code is
> > in flux.

> I would go further. The kernel behaviour has changed, and we have to
> deal with platforms that assume the old behaviour. That means either
> defaulting to leaving enabled regulators/clocks alone unless there is
> a flag in the DT saying they can be power managed, or black listing
> platforms that are known to depend on the regulator being on.

For regulators there is essentially a flag in DT already - the
regulators should not be described in DT if the OS isn't supposed to be
managing them.

> Updating the device tree must not be required to get the kernel to
> boot, but it is valid to require a DT upgrade to get better
> performance (battery life) out of the platform.

This has got to be a blacklist then, and it seems like we've got to fix
simplefb to actually support managing the resources it's using.  The
current plan does not seem at all sensible - we're talking about adding
hacks in every subsystem that provides resources and bodging DTs in
order to work around simplefb.

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