Message-ID: <20150824125758.GA7557@n2100.arm.linux.org.uk>
Date:	Mon, 24 Aug 2015 13:57:58 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Rob Herring <robherring2@...il.com>
Cc:	Yakir Yang <ykk@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>,
	Thierry Reding <treding@...dia.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Inki Dae <inki.dae@...sung.com>, Joe Perches <joe@...ches.com>,
	Sean Paul <seanpaul@...gle.com>, Takashi Iwai <tiwai@...e.de>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	Vincent Palatin <vpalatin@...omium.org>,
	linux-rockchip@...ts.infradead.org,
	Kishon Vijay Abraham I <kishon@...com>,
	David Airlie <airlied@...ux.ie>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Doug Anderson <dianders@...gle.com>,
	Rob Herring <robh+dt@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Mark Yao <mark.yao@...k-chips.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Daniel Kurtz <djkurtz@...gle.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Kumar Gala <galak@...eaurora.org>,
	Ajay kumar <ajaynumb@...il.com>,
	Andy Yan <andy.yan@...k-chips.com>
Subject: Re: [PATCH v3 06/14] Documentation: drm/bridge: add document for
 analogix_dp

On Sun, Aug 23, 2015 at 06:23:14PM -0500, Rob Herring wrote:
> On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang <ykk@...k-chips.com> wrote:
> > +       -analogix,color-depth:
> > +               number of bits per colour component.
> > +                       COLOR_6 = 0, COLOR_8 = 1, COLOR_10 = 2, COLOR_12 = 3
> 
> This seems pretty generic. Just use 6, 8, 10, or 12 for values. And
> drop the vendor prefix.

Please think about this some more.  What does "color-depth" mean?  Does it
mean the number of bits per colour _component_, or does it mean the total
number of bits to represent a particular colour.  It's confusing as it
stands.

> > +Optional properties for dp-controller:
> > +       -analogix,hpd-gpio:
> > +               Hotplug detect GPIO.
> > +                       Indicates which GPIO should be used for hotplug
> > +                       detection
> 
> We should align with "hpd-gpios" used by HDMI connector binding. Or do
> we need a DP connector binding that this should be defined in?
> Probably so.
> 
> The DRM related bindings are such a cluster f*ck with everyone picking
> their own way to do things. Just grep hpd in bindings for starters.
> That is just the tip.

I'm not surprised one iota that DRM bindings are a mess.  There's no one
overlooking the adoption of DRM bindings, so surprise surprise, everyone
does their own thing.  This is exactly what happens every time in that
scenario.  It's not a new problem.

When we adopted the graph bindings for iMX DRM, I thought exactly at that
time "it would be nice if this could become the standard for binding DRM
components together" but I don't have the authority from either the DT
perspective or the DRM perspective to mandate that.  Neither does anyone
else.  That's the _real_ problem here.

I've seen several DRM bindings go by which don't use the of-graph stuff,
which means that they'll never be compatible with generic components
which do use the of-graph stuff.

Like you say, it's a mess, but it's a mess of our own making, because no
one has the authority to regulate this.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
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