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[209.85.219.180]) by smtp.gmail.com with ESMTPSA id h5sm726434qkg.122.2021.05.19.14.06.17 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 May 2021 14:06:17 -0700 (PDT) Received: by mail-yb1-f180.google.com with SMTP id y36so3340684ybi.11 for ; Wed, 19 May 2021 14:06:17 -0700 (PDT) X-Received: by 2002:a25:734e:: with SMTP id o75mr2168098ybc.405.1621458376733; Wed, 19 May 2021 14:06:16 -0700 (PDT) MIME-Version: 1.0 References: <20210517200907.1459182-1-dianders@chromium.org> <20210517130450.v7.3.I98bf729846c37c4c143f6ab88b1e299280e2fe26@changeid> <20210519200156.GA3535665@robh.at.kernel.org> In-Reply-To: <20210519200156.GA3535665@robh.at.kernel.org> From: Doug Anderson Date: Wed, 19 May 2021 14:06:04 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v7 03/10] dt-bindings: drm/bridge: ti-sn65dsi86: Add aux-bus child To: Rob Herring Cc: Andrzej Hajda , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Sam Ravnborg , Stanislav Lisovskiy , Lyude Paul , Thierry Reding , Stephen Boyd , Bjorn Andersson , linux-arm-msm , Maarten Lankhorst , Linus W , dri-devel , Rob Clark , Steev Klimaszewski , Daniel Vetter , David Airlie , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi, On Wed, May 19, 2021 at 1:02 PM Rob Herring wrote: > > On Mon, May 17, 2021 at 01:09:00PM -0700, Douglas Anderson wrote: > > We want to be able to list an eDP panel as a child of a ti-sn65dsi86 > > node to represent the fact that the panel is connected to the bridge's > > DP AUX bus. Though the panel and the bridge chip are connected in > > several ways, the DP AUX bus is the primary control interface between > > the two and thus makes the most sense to model in device tree > > hierarchy. > > > > Listing a panel in this way makes it possible for the panel driver to > > easily get access to the DP AUX bus that it resides on, which can be > > useful to help in auto-detecting the panel and for turning on various > > bits. > > > > NOTE: it's still possible to continue using the bridge chip and point > > to a panel that _isn't_ listed as a child of the bridge chip (since > > it's worked that way previously), but that should be deprecated since > > there is no downside to listing the panel under the bridge chip. > > > > The idea for this bus's design was hashed out over IRC [1]. > > > > [1] https://people.freedesktop.org/~cbrill/dri-log/?channel=dri-devel&date=2021-05-11 > > > > Signed-off-by: Douglas Anderson > > --- > > Possibly we might want something fancier that could be included by > > other eDP controller bindings. If we want to do this, I'd love to be > > pointed at a good example to follow. > > > > Changes in v7: > > - ti-sn65dsi86: Add aux-bus child patch new for v7. > > > > .../bindings/display/bridge/ti,sn65dsi86.yaml | 22 ++++++++++++++++++- > > 1 file changed, 21 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml > > index 26932d2e86ab..51f5a29e216c 100644 > > --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml > > +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml > > @@ -70,6 +70,11 @@ properties: > > const: 1 > > description: See ../../pwm/pwm.yaml for description of the cell formats. > > > > + aux-bus: > > As this is a node: > > type: object > > > + description: > > + It is recommended that you place your panel under the aux-bus node > > + here to represent the control hierarchy. > > + > > ports: > > $ref: /schemas/graph.yaml#/properties/ports > > > > @@ -201,11 +206,26 @@ examples: > > > > port@1 { > > reg = <1>; > > - endpoint { > > + sn65dsi86_out: endpoint { > > remote-endpoint = <&panel_in_edp>; > > }; > > }; > > }; > > + > > + aux-bus { > > + panel { > > We should perhaps have a separate aux-bus schema. Yeah. Before spending lots of time digging into how to do this I wanted to see if anyone was going to give me a big-old NAK on the whole approach. ;-) I guess I'd make a file called "dp-aux-bus.yaml" (maybe right under bindings/display?) and then I'd include it like this: aux-bus: $ref: "../dp-aux-bus.yaml#" > Something should > define the child node is 'panel' and nothing else. At the moment the code also requires that the node name is 'aux-bus'. Any objections to that? > Though perhaps > connectors are valid too? They might be. We could always add it later?