linux-kernel - [PATCH v3 1/2] dt-bindings: drm/bridge: Add no-hpd property

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Message-ID: <20250205115025.3133487-2-h-shenoy@ti.com>
Date: Wed, 5 Feb 2025 17:20:24 +0530
From: Harikrishna Shenoy <h-shenoy@...com>
To: <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>, <rfoss@...nel.org>,
        <Laurent.pinchart@...asonboard.com>, <jonas@...boo.se>,
        <jernej.skrabec@...il.com>, <simona@...ll.ch>,
        <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <jani.nikula@...el.com>, <j-choudhary@...com>,
        <sui.jingfeng@...ux.dev>, <viro@...iv.linux.org.uk>,
        <r-ravikumar@...com>, <sjakhade@...ence.com>, <yamonkar@...ence.com>,
        <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 1/2]  dt-bindings: drm/bridge: Add no-hpd property

From: Rahul T R <r-ravikumar@...com>

The mhdp bridge can work without its HPD pin hooked up to the connector,
but the current bridge driver throws an error when hpd line is not
connected to the connector. For such cases, we need an indication for
no-hpd, using which we can bypass the hpd detection and instead use the
auxiliary channels connected to the DP connector to confirm the
connection.
So add no-hpd property to the bindings, to disable hpd when not
connected or unusable due to DP0-HPD not connected to correct HPD 
pin on SOC like in case of J721S2.

Signed-off-by: Rahul T R <r-ravikumar@...com>
Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
---
 .../devicetree/bindings/display/bridge/cdns,mhdp8546.yaml   | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
index c2b369456e4e..3a6c6d837593 100644
--- a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml
@@ -57,6 +57,12 @@ properties:
   interrupts:
     maxItems: 1
 
+  cdns,no-hpd:
+    type: boolean
+    description:
+      Set if the HPD line on the bridge isn't hooked up to anything or is
+      otherwise unusable.
+
   ports:
     $ref: /schemas/graph.yaml#/properties/ports
 
-- 
2.34.1