[U-Boot] [linux-sunxi] Re: [PATCH] video: add cfb console driver for sunxi

[Maxime Ripard]

On Mon, Aug 04, 2014 at 05:05:00PM +0200, Luc Verhaegen wrote:
> On Mon, Aug 04, 2014 at 10:39:13AM +0200, Hans de Goede wrote:
> > Hi Luc,
> > 
> > First of all many thanks for your work on this.
> > 
> > ATM I don't have time to do a full review, but I don't expect there
> > to be too many suprises when I do find the time.
> > 
> > Really my only concern is the handover of the reserved memory, etc. to
> > the kernel. We need to get a plan in place for that *before* this can
> > be merged. Note I don't want to raise any artificial barriers here,
> > I would love to see this merged ASAP. But I don't want to paint us
> > in a corner where u-boot having hdmi console support makes it harder
> > to get kms support in the kernel going. I think we can both agree on that.
> >
> > So I really want to see some plan how this will work in place before merging.
> > Note just a plan, I don't expect kernel patches ready to be merged for this,
> > just a good idea / sketch of how all the bits will fit together.
> 
> Memory is not the biggest worry.
> 
> Some kernel code needs to claim clocks if the mode is to cleanly survive 
> the start of the kernel. If not, there is no coming back until a proper 
> display driver runs. If the simplefb driver claims these clocks, then 
> the simplefb driver also must release these clocks, and this driver 
> should then never be started again, so it should set the simplefb dt 
> node status to "disabled".

I'm probably missing a bit of context, but one thing I still don't get
is why you're taking into account the simplefb <-> KMS handover. It's
a case that shouldn't exist.

By essence, simplefb has never been meant for that. It's been meant to
have a temporary solution until a full-fledged driver is merged in the
kernel. Which is exactly the case we're into.

But once the KMS driver gone, I'd just expect simplefb to go away.

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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