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Luca Ceresoli 73cb588a6d drm/bridge: imx8mp-hdmi-tx-connector-fixup: add an hdmi-connector when missing using a DT overlay at boot time
The imx8mp-hdmi-tx is one of many drivers based on dw-hdmi. dw-hdmi in turn
can operate in two different modes, depending on the platform data as set
by the driver:

 A. hdmi->plat_data->output_port = 0:
    the HDMI output (port@1) in device tree is not used [0]

 B. hdmi->plat_data->output_port = 1:
    the HDMI output (port@1) is parsed to find the next bridge

The imx8mp-hdmi-tx driver falls in case A. This implies next_bridge will
always be NULL, and so dw_hdmi_bridge_attach() [1] will always fail if
called with the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag.

In fact case A assumes that DRM_BRIDGE_ATTACH_NO_CONNECTOR is not set and
in that case it adds an HDMI Type A connector programmatically at bridge
attach time.

Support for DRM_BRIDGE_ATTACH_NO_CONNECTOR is implemented by dw-hdmi.c in
case B. However switching to base B requires that port@1 is connected to a
"next bridge" DT node, typically the HDMI connector, because dw-hdmi won't
add the connector when using DRM_BRIDGE_ATTACH_NO_CONNECTOR.

Many dts files for imx8mp-based boards in the kernel have such a connector
described and linked to port@1, so the pipeline will be fully attached up
to a display-connector and a drm_connector added by the
bridge-connector. Sadly some of those dts files don't have the connector
described. Adding it would solve the problem easily, but this would break
existing devices which do not update the dtb when upgrading to a newer
kernel.

In preparation for switching to case B while preserving backward
compatibility for such devices, introduce a module adding the
hdmi-connector node to the live device tree at init time. This will allow
the dw-hdmi code to find the next bridge (the one wrapping the
hdmi-connector) and let the pipeline work as before.

The module is inserted only if there is no endpoint in port@1. So boards
whose device tree describe the connector will not have the device tre
modified, and will start isntantiating the correct HDMI connector type as
described in the device tree.

For boards lacking a connector description in DT the overlay will be added,
abd the HDMI connector will be Type A, which is a reasonable fallback and
is what the driver is currently doing.

[0] https://elixir.bootlin.com/linux/v7.0-rc1/source/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c#L3310
[1] https://elixir.bootlin.com/linux/v7.0-rc1/source/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c#L2907

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Link: https://patch.msgid.link/20260407-drm-lcdif-dbanc-v4-8-247a16e61ef9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
2026-04-14 13:52:32 +02:00
arch RISC-V updates for v7.0-rc7 2026-04-05 14:43:47 -07:00
block block-7.0-20260305 2026-03-06 08:36:18 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto This push contains the following changes: 2026-04-02 17:29:48 -07:00
Documentation dt-bindings: display: panel: add Waveshare LCD panels 2026-04-10 00:20:22 +03:00
drivers drm/bridge: imx8mp-hdmi-tx-connector-fixup: add an hdmi-connector when missing using a DT overlay at boot time 2026-04-14 13:52:32 +02:00
fs mm: add gpu active/reclaim per-node stat counters (v2) 2026-04-08 06:52:47 +10:00
include drm/bridge: dw-hdmi: document the output_port field 2026-04-14 13:52:31 +02:00
init hardening fixes for v7.0-rc6 2026-03-25 14:47:18 -07:00
io_uring io_uring-7.0-20260403 2026-04-03 11:58:04 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Misc scheduler fixes: 2026-04-05 13:45:37 -07:00
lib Crypto library fixes for v7.0-rc7 2026-03-30 13:40:48 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm ttm/pool: port to list_lru. (v2) 2026-04-08 06:52:47 +10:00
net bpf-fixes 2026-04-02 18:59:56 -07:00
rust DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
samples DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
scripts DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
security Landlock fix for v7.0-rc6 2026-03-26 12:03:37 -07:00
sound USB/Thunderbolt fixes for 7.0-rc7 2026-04-05 10:00:26 -07:00
tools RISC-V updates for v7.0-rc7 2026-04-05 14:43:47 -07:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM generic changes for 7.0 2026-03-11 18:01:55 +01:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Merge tag 'drm-intel-next-2026-03-30' of https://gitlab.freedesktop.org/drm/i915/kernel into drm-next 2026-03-31 16:38:50 +10:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: remove Thomas Falcon from IBM ibmvnic 2026-03-05 07:35:45 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge tag 'drm-msm-next-2026-04-02' of https://gitlab.freedesktop.org/drm/msm into drm-next 2026-04-03 18:57:00 +10:00
Makefile Linux 7.0-rc7 2026-04-05 15:26:23 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst