Re: [PATCH 4/6] dt-bindings: display: armada: Add display subsystem binding

From: Rob Herring <robh+dt@kernel.org>
To: Lubomir Rintel <lkundrak@v3.sk>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, Russell King <linux@armlinux.org.uk>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/6] dt-bindings: display: armada: Add display subsystem binding
Date: Mon, 4 Mar 2019 11:35:33 -0600	[thread overview]
Message-ID: <CAL_JsqJ8rovEM4RtkJKwTeDrRotVr59EmU-_1ApR+c9yxB8k2Q@mail.gmail.com> (raw)
In-Reply-To: <4e89406842c4821d590dc6518076cfe6f19cc6b9.camel@v3.sk>

On Sun, Feb 24, 2019 at 10:15 AM Lubomir Rintel <lkundrak@v3.sk> wrote:
>
> On Fri, 2019-02-22 at 14:23 -0600, Rob Herring wrote:
> > On Wed, Feb 13, 2019 at 4:37 PM Lubomir Rintel <lkundrak@v3.sk> wrote:
> > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote:
> > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote:
> > > > > The Marvell Armada DRM master device is a virtual device needed to list all
> > > > > nodes that comprise the graphics subsystem.
> > > > >
> > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> > > > > ---
> > > > >  .../display/armada/marvell-armada-drm.txt     | 24 +++++++++++++++++++
> > > > >  1 file changed, 24 insertions(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt
> > > > > index de4cca9432c8..3dbfa8047f0b 100644
> > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt
> > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt
> > > > > @@ -1,3 +1,27 @@
> > > > > +Marvell Armada DRM master device
> > > > > +================================
> > > > > +
> > > > > +The Marvell Armada DRM master device is a virtual device needed to list all
> > > > > +nodes that comprise the graphics subsystem.
> > > > > +
> > > > > +Required properties:
> > > > > +
> > > > > + - compatible: value should be "marvell,dove-display-subsystem",
> > > > > +   "marvell,armada-display-subsystem"
> > > > > + - ports: a list of phandles pointing to display interface ports of CRTC
> > > > > +   devices
> > > > > + - memory-region: phandle to a node describing memory to be used for the
> > > > > +   framebuffer
> > > > > +
> > > > > +Example:
> > > > > +
> > > > > +       display-subsystem {
> > > > > +               compatible = "marvell,dove-display-subsystem",
> > > > > +                            "marvell,armada-display-subsystem";
> > > > > +               memory-region = <&display_reserved>;
> > > > > +               ports = <&lcd0_port>;
> > > >
> > > > If there is only one device, you don't need this virtual node.
> > >
> > > Before I follow up on this and submit a version without the virtual
> > > node, I'm wondering: is it okay that the bindings for the LCDC and the
> > > framebuffer are in the same file, or would it be preferrable if they
> > > were separate? Both styles seem to be used for the display bindings.
> >
> > framebuffer as in the kernel fbdev? Really, that should be the same
> > binding. It's the same h/w after all. However, there have been cases
> > where things deviated. So I don't have a good answer.
>
> No, not the fbdev device, that one is managed by drmfb and is not
> expressed in DT. I meant the reserved-memory node that sets aside
> memory for the framebuffers.
>
> See patch "[RFC 03/16] dt-bindings: display: armada: Add framebuffer
> reserved-mem binding". Perhaps that part should even go to
> Documentation/devicetree/bindings/reserved-memory/.

Okay.

A separate file will be better and probably
Documentation/devicetree/bindings/reserved-memory/ is the best
location.

Rob
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