About
The Display Next Hackfest is an event where talented developers will gather to explore the latest technologies and trends in the Linux Display Stack. It has an unconference format where participants propose topics for presenting, roadmapping, discussing and examining together. It aims to unblock bottlenecks, design solutions, raise pitfalls and accommodate the needs of each layer of the display stack. Participants should feel free to propose any topic which interests them. Some topics from the previous edition include: HDR and color management, frame timing and variable refresh rate (VRR), atomic flips, testing and CI, etc.
Plans and Goals
- Keep moving! Continue your work on upstream design, implementation and documentation until the hackfest.
- “Are you okay with that?” Present the current status of your work, explain decisions, concerns and results. Let’s compromise.
- Share your pains. What is well aligned with the generic approach? What is not (singularities) and how can we find room for it? Whatever your doubts, we resolve them together!
- “Something went wrong.” Share failing tests or inconsistent results. Let’s take a look together and find how to overcome them!
The hackfest will last three days following a “Unconference” format. Check the event timetable and agenda below.
* Information about the previous year can be found on Shell Display Next 2023 wiki.
Timetable (Central European Summer Time - CEST)
Time (CEST) / Date | Tue, May 14 | Wed, May 15 | Thu, May 16 |
---|---|---|---|
09:00 - 9:30 | Walk to Igalia HQ | Walk to Igalia HQ | Walk to Igalia HQ |
09:30 - 10:10 | Welcome! (Igalia HQ & participants intro) | Recap & Planning | Recap & Planning |
10:10 - 11:40 | Introduction (Participants & Topics) | Session: Real time scheduling & async KMS API | Session: Display Control & Session: Display Mux |
11:40 - 12:00 | 20-min break* | 20-min break* | 20-min break* |
12:00 - 13:30 | Session: VRR & Frame timing | Session: Power Savings vs Color/Latency | Session: VRR & Frame timing & Session: Content-Adaptive Scaling & Sharpening |
13:30 - 14:30 | Lunch* | Lunch* | Lunch* |
14:30 - 16:00 | Session: HDR & Color Management (kernel) | Session: HDR & Color Management (userspace) | Wrapping-up (length: 1h) |
16:00 - 16:20 | 20-min break* | 20-min break* | |
16:20 - 18:30 | Session: HDR & Color Management (Use-cases/Testing) | Session: Strategy for video and gaming use-cases | Social Activity |
20:30 | Hackfest Dinner (sponsored by Igalia) |
* Lunches and coffee-breaks offered to participants in the office by Igalia.
Find more details about general schedule and sessions here.
Agenda
KMS Color/HDR
- Proposal with new DRM object type:
- Presentation of GPU-vendors features;
- Status-update of plane color management pipeline per vendor on Linux;
- HDR/Color Use-cases:
- Google/ChromeOS GFX view about HDR/per-plane color management and VKMS;
- HDR gainmap images and how we should think of HDR;
- Pain points and wish lists of HDR images and video on ChromeOS.
- Post-blending Color Pipeline.
Color/HDR testing/CI
- VKMS status-update;
- Chamelium boards, video capture.
Wayland
- Linux color handling and management;
- color-management protocol status-update;
- color-representation and video playback.
Display control
- HDR signalling status-update;
- backlight status-update;
- EDID and DDC/CI.
Strategies for video and gaming use-cases
- Multi-plane support in compositors:
- Underlay, overlay, or mixed strategy for video and gaming use-cases;
- KMS Plane UAPI to simplify the plane arrangement problem;
- Shared plane arrangement algorithm desired.
- HDR video and hardware overlays.
Frame timing and VRR
- Frame timing:
- Limitations of uAPI;
- Current user space solutions;
- Brainstorm better uAPI;
- Cursor/overlay plane updates with VRR;
- KMS commit and buffer-readiness deadlines;
Power Saving vs Color/Latency
- ABM (adaptive backlight management);
- PSR1 latencies;
- Power optimization vs color accuracy/latency requirements.
Content-Adaptive Scaling & Sharpening
- Content Adaptive Scalers on display hardware;
- New drm_colorop for content adaptive scaling;
- Proprietary algorithms.
Display Mux
- Laptop muxes for switching of the embedded panel between the integrated GPU and the discrete GPU;
- Seamless/atomic hand-off between drivers on Linux desktops.
Real time scheduling & async KMS API
- Potential benefits: lower latency input feedback, better VRR handling, buffer synchronization, etc.
- Issues around “async” uAPI usage and async-call handling.
More details here.
Participants
See the list of participants here.