Re: [RFC v2 1/4] dt-bindings: drm/mediatek: Add Mediatek display subsystem dts binding

From: Philipp Zabel <p.zabel@pengutronix.de>
To: Rob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Paul Bolle <pebolle@tiscali.nl>, YT Shen <yt.shen@mediatek.com>,
	Jitao Shi <jitao.shi@mediatek.com>,
	Pawel Moll <pawel.moll@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Cawa Cheng <cawa.cheng@mediatek.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	linux-mediatek@lists.infradead.org,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	Kumar Gala <galak@codeaurora.org>,
	Matthias Brugger <matthias.bgg@gmail.com>
Subject: Re: [RFC v2 1/4] dt-bindings: drm/mediatek: Add Mediatek display subsystem dts binding
Date: Thu, 01 Oct 2015 10:59:17 +0200	[thread overview]
Message-ID: <1443689957.3272.18.camel@pengutronix.de> (raw)
In-Reply-To: <CAL_JsqLcraiS+Yq48-m-xTksohU5wPSPrjtjV2GLzDTSDcUCUA@mail.gmail.com>

Am Mittwoch, den 30.09.2015, 12:13 -0500 schrieb Rob Herring:
> On Mon, Sep 21, 2015 at 3:11 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> > Note how the display-subsystem node overlaps the larb node. Is that
> > acceptable?
> 
> Given what the graph looks like, perhaps. However, do you really need
> a container node? It only serves to provide a list of nodes (e.g. all
> the children) to include as components. There are other ways to
> determine this list. You could find all nodes just searching
> compatible strings for each component. You just need to bind the drm
> driver to some other DT node. Is there no node you can pick as the
> master component?

There is the mmsys clock-controller node at the top of the MMSYS address
space (0x14000000-0x14ffffff):

	mmsys: clock-controller@14000000 {
		compatible = "mediatek,mt8173-mmsys", "syscon";
		reg = <0 0x14000000 0 0x1000>;
		#clock-cells = <1>;
	};

Its register space also contains the MMSYS_CONFIG region that controls
the multiplexers between the display function blocks, so that would be a
good candidate.
No driver binds to this node yet, the clocks are registered with
CLK_OF_DECLARE.

I'll try to bind to this node and have the driver find sibling nodes
using their compatible strings.

thanks
Philipp

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