Re: [PATCH] dt-bindings: Add schemas for simple-framebuffer

[Maxime Ripard <maxime.ripard@bootlin.com>]

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Hi Rob,

On Wed, Mar 27, 2019 at 08:20:18AM -0500, Rob Herring wrote:
> On Tue, Mar 26, 2019 at 4:35 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > On Mon, Mar 25, 2019 at 11:27:36AM -0500, Rob Herring wrote:
> > > On Mon, Mar 25, 2019 at 8:54 AM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > > >
> > > > The simple framebuffer is a binding that allows the bootloader to setup a
> > > > framebuffer, describe it in the Device Tree for the OS to pick it up and
> > > > use it as is.
> > > >
> > > > Replace the current binding by a schema to allow the validation tools to
> > > > check those nodes.
> > > >
> > > > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > > > Cc: Chen-Yu Tsai <wens@csie.org>
> > > > Cc: Hans de Goede <hdegoede@redhat.com>
> > > > Cc: Maxime Jourdan <mjourdan@baylibre.com>
> > > > Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> > > >
> > > > ---
> > > >
> > > > Rob,
> > > >
> > > > Even though the node itself is properly described, I still end up with some
> > > > validation warnings when the chosen node is validated (basically
> > > > complaining that ranges, and the framebuffer nodes shouldn't be here, since
> > > > we haven't described them in the chosen schemas).
> > >
> > > Having 'ranges' is a bit strange because 'chosen' doesn't have an
> > > address. We can add #address-cells, #size-cells and framebuffer child
> > > node to the base chosen schema.

I've just sent a github PR to do that.

> > Maybe that's just cargo cult, but both the amlogic and the sunxi DT
> > have ranges in chosen. Shouldn't we need it so that the address is
> > decoded properly?
>
> I don't think so. If you have #{size,address}-cells then that should
> be enough. Lack of ranges should just mean that any translation stops
> at that level. But it is possible that the kernel code requires
> translation to go all the way to the root for memory addresses. I
> haven't checked.

I tested it, and it looks like of_translate_address returns EINVAL if
ranges is missing. If that's not desired, then I can look into it.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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