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

[Maxime Ripard]

On Tue, Aug 05, 2014 at 11:37:11PM +0200, Michal Suchanek wrote:
> > 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.
> 
> It's a permanent temporary solution. Same as offb/vesafb/uefi and
> other unaccelerated drivers. It will be needed for platforms on which
> KMS is not (yet) fully supported or happens to break.

Yeah, I get that part, but there's no handover in this case.

> Also how else do you express the fact that u-boot has left the display
> enabled other than generating the simplefb DT node?

Just like timers, UARTs, i2c, ethernet, and any other controller that
might be used by the OS: the OS should deal with it.

We don't use a simplefb-equivalent for the PMIC, or for the GMAC, I
don't see why we should use one here to deal with that issue.

What resources are you afraid to waste here? clocks are reclaimed
automatically, memory is not, but simplefb won't help, see our
discussion on the othre thread about this patch.

> Note that the KMS driver will be probably unsuitable for early console
> while the simplefb driver can just write into the framebuffer set up
> by u-boot.

They both step in at the same time. simplefb is not a solution for
that either.

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