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

From: Rob Herring <robh@kernel.org>
To: Philipp Zabel <p.zabel@pengutronix.de>
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, 1 Oct 2015 07:58:42 -0500	[thread overview]
Message-ID: <CAL_Jsq+aBxjvPyAR3nUtXny6JwgcopSCENrBaGzo7OKXFA1cvg@mail.gmail.com> (raw)
In-Reply-To: <1443689957.3272.18.camel@pengutronix.de>

On Thu, Oct 1, 2015 at 3:59 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> 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.

That doesn't seem like a good choice since there are other functions
in the block. I was thinking one of the display related blocks like
whatever block provides the main crtc functions.

Rob
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