From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH v2 1/9] dt-bindings: display: sun4i: Add component endpoint ID numbering scheme Date: Tue, 2 May 2017 16:54:53 +0200 Message-ID: <20170502145453.3moqzsr3venpn4mu@lukather> References: <20170421083857.29636-1-wens@csie.org> <20170421083857.29636-2-wens@csie.org> <20170428134841.cc5jrqhunh2rxhog@rob-hp-laptop> Reply-To: maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="yyfdqyfvjibu4hc6" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: <20170428134841.cc5jrqhunh2rxhog@rob-hp-laptop> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Rob Herring Cc: Chen-Yu Tsai , David Airlie , Mark Rutland , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org List-Id: devicetree@vger.kernel.org --yyfdqyfvjibu4hc6 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Hi, On Fri, Apr 28, 2017 at 08:48:41AM -0500, Rob Herring wrote: > On Fri, Apr 21, 2017 at 04:38:49PM +0800, Chen-Yu Tsai wrote: > > The Allwinner display pipeline contains many hardware components, some > > of which can consume data from one of multiple upstream components. > > The numbering scheme of these components must be encoded into the device > > tree so the driver can figure out which component out of two or more of > > the same type it is supposed to use or program. > > > > This patch adds the constraint that local endpoint IDs must be the index > > or number of the remote endpoint's hardware block, for all components > > in the display pipeline up to the TCONs. > > > > Signed-off-by: Chen-Yu Tsai > > --- > > Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > index 57a8d0610062..7acdbf14ae1c 100644 > > --- a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > +++ b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt > > @@ -4,6 +4,16 @@ Allwinner A10 Display Pipeline > > The Allwinner A10 Display pipeline is composed of several components > > that are going to be documented below: > > > > +For the input port of all components up to the TCON in the display > > +pipeline, if there are multiple components, the local endpoint IDs > > +must correspond to the index of the upstream block. For example, if > > +the remote endpoint is Frontend 1, then the local endpoint ID must > > +be 1. > > + > > +Conversely, for the output ports of the same group, the remote endpoint > > +ID must be the index of the local hardware block. If the local backend > > +is backend 1, then the remote endpoint ID must be 1. > > It would be clearer if you just explicitly listed IDs and their > connections. From how this is worded, it would not work if you had > connections like this: > > DevA 0 > DevA 1 > DevB 0 > DevB 1 > > These would need to be endpoints 0-3 in TCON, and that doesn't reflect > the remote devices' index. Chen-Yu, can you send a patch to rephrase the doc that way? Thanks, Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com --yyfdqyfvjibu4hc6--