linux-kernel - [PATCH v2 0/2] "no-hpd" support in CDNS DP bridge driver

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Date:   Wed, 5 Apr 2023 19:54:38 +0530
From:   Jayesh Choudhary <j-choudhary@...com>
To:     <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <krzysztof.kozlowski@...aro.org>
CC:     <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>,
        <rfoss@...nel.org>, <Laurent.pinchart@...asonboard.com>,
        <jonas@...boo.se>, <jernej.skrabec@...il.com>, <airlied@...il.com>,
        <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <sam@...nborg.org>,
        <jani.nikula@...el.com>, <tzimmermann@...e.de>,
        <javierm@...hat.com>, <ville.syrjala@...ux.intel.com>,
        <r-ravikumar@...com>, <lyude@...hat.com>,
        <alexander.deucher@....com>, <sjakhade@...ence.com>,
        <yamonkar@...ence.com>, <a-bhatia1@...com>,
        <tomi.valkeinen@...asonboard.com>, <j-choudhary@...com>
Subject: [PATCH v2 0/2] "no-hpd" support in CDNS DP bridge driver

In J721s2 EVM, DP0 HPD is not connected to correct HPD pin on SOC
which results in HPD detect as always connnected, so when display
is not connected driver continuously retries to read EDID and DPCD
registers.

To handle such cases add support for no hpd configuration in
cdns-mhdp driver.

DT changes for display in j721s2 will be posted once we have no-hpd
support and multilink DP support[1] merged.

[1]:
<https://lore.kernel.org/all/20230227133104.29788-1-sjakhade@cadence.com/>

Changelog v1->v2:
- edit the commit message for the bindings to clarify why we exactly need
  no-hpd indication for mhdp.

v1 patch-link:
<https://lore.kernel.org/all/20230316140823.234263-1-j-choudhary@ti.com/>

Rahul T R (2):
  dt-bindings: drm/bridge: Add no-hpd property
  drm: bridge: cdns-mhdp8546: Add support for no-hpd

 .../display/bridge/cdns,mhdp8546.yaml         |  6 +++
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 37 ++++++++++++++++---
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  1 +
 3 files changed, 39 insertions(+), 5 deletions(-)

-- 
2.25.1