vc4-fkms: Add hotplug support

Open
#3,205 2 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
c

Research direction

The proposal concerns FKMS HDMI hotplug control and DRM/KMS connector status; start by tracing how FKMS creates HDMI display outputs and reports connector state. Done means HDMI outputs are created consistently and monitor enable/disable behavior follows connector status for the supported HDMI, DSI, DPI, and SDTV combinations.

Written by the indexing model from the issue text.

Description

Waiting for internal comment

Task tracking / proposal.
As noted in https://github.com/raspberrypi/firmware/issues/1243, routing HDMI audio sensibly is currently a bit messy due to FKMS hiding whether it is connector HDMI0 or HDMI1 into which a monitor is connected. What DRM/KMS sees as HDMI-1 could therefore be a single monitor plugged into either connector.

Bottom line is we can have two displays active at a time due to only two HVS channels being available (the third channel is dedicated to the transposer).
The supported use cases are

  • HDMI0 & HDMI1
  • HDMI0 & DSI1
  • HDMI0 & DPI
  • SDTV.

(DSI and DPI are handled in the same way and named DSI-1 via DRM/KMS.)

If we add HDMI hotplug control to FKMS, then we can always create the HDMI display outputs in a consistent way, and the connector status should do the magic within the frameworks to enable and disable the monitors at appropriate times.

Dominant language
C
Stars
13.2k
Forks
5.5k
Avg merge
2d 21h
Merged PRs (30d)
21

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from raspberrypi/linux

All issues in raspberrypi/linux

Similar issues

More C issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.