Runtime display switch implementation in a Linux DRM bridge subsystem

5 Oct 2022, 17:20
201 (Opus Hall)


Opus Hall

30 S 10th Street, Minneapolis, MN
Talk (half slot, Wineconf and FOSS XR only) Main Track


Jagan Teki


Due to rapid graphical industrial evolution, display interface providers are coming up with display bridges to address the mismatch between application-specific display interfaces vs on-chip display controllers (like from SoC, MCU). This simplifies the on-chip solution provider to concentrate on a single display interface so that the application can choose a direct interface or any other interface by using a display bridge.

Display bridges are linear and one-to-one display interface convertors however the display interface provider makes the further complexity to these bridges and came up with a display switch that can take a single display interface input and convert more than one display interface output. This kind of display switch has a variety of use cases in industrial and consumer graphic applications. A couple of display switch designs are available in the market via conventional mux with display bridges and a complete converter bridge chip with a one-to-two interface.

As the Linux DRM subsystem progresses toward DRM bridges, these display switches are well suited to be part of DRM bridges. Supporting display switches in Linux DRM is complex and new as DRM bridges are linear in architecture. In order to operate display switches via drm bridge, it requires a pipeline to non-linear and tree structure as switch operate more than one output.

This talk will explain how this display switching is implemented in DRM bridges on top of fbcon and KMS applications by considering real-time solutions of MIPI DSI host bridge with mux switch followed by HDMI and LVDS bridges on NXP i.MX8M platform.

After that, this talk explains the current working status of runtime display switching, issues, community suggestions, and future plans.

Note: links for community discussion on this topic

Code of Conduct Yes
GSoC, EVoC or Outreachy No
For which conference do you send the proposal? X.Org Developers Conference 2022

Primary author

Presentation Materials

2023 Platinum Sponsor
2023 Gold Sponsors
2023 Silver Sponsors
The Linux Foundation
2023 Bronze Sponsors
Khronos Group
2023 Supporters
A Coruña Turismo
Raspberry Pi