1. Shell & Display Next hackfest

Brno, 24-26 April inclusive

Primary contact: Carlos Soriano Sanchez <csoriano@redhat.com>
Secondary contact: Tomas Popela <tpopela@redhat.com>

1.1. Relevant GNOME team

Shell & mutter, possibly Design. Teams outside of GNOME will be key too, for KMS/DRM, Mesa, etc.

1.2. Description

Planning and development of the technical infrastructure for various features for display-next technologies, specifically those that need GNOME Shell to work in tandem with the GPU stack. One of the main examples of this is HDR support.

This hackfest intends to put together engineers across the display/GPU stack, including folks from freedesktop and the upstream kernel. It's a great opportunity for GNOMErs to meet and collaborate with members of other communities.

The proposed length of the hackfest is 3 full days. A local sponsored activity will be done the first day during the afternoon, which will include a dinner.

1.2.1. Agenda, goals

Goals The main goal is to plan the next 1-2 years of work and direction in how to support HDR, VRR and other new GPU and graphics technologies that are exposed to the final user through Mutter and Shell.

In addition, the second main goal is to discuss, plan and agree on how to improve KMS and Wayland APIs to better accommodate user space needs for these technologies, specially necessary for HDR.

The third main but optional goal is for the UXD team to discuss the next iteration of Shell designs, and expose their needs to the GPU, graphics and Shell/Mutter engineers to gather feedback on what's feasible and what APIs would be necessary.

Agenda

• HDR - Leads: Jonas, Sebastian, Harry Wentland
  • HDR modes (PQ, HLG, SBTM, and Metadata)
  • Approaches for compositing SDR, color managed SDR and HDR
    • ICC workflow
    • Implicit color managed workflow
    • Gamut and tone mapping
    • Linear spaces for blending, scaling
  • Viewing environment adjustment
    • Brightness/backlight adjustment
    • PQ absolute luminance TF
    • Tone mapping
  • Mutter and GTK roadmap
  • Wayland color-representation and color-management protocols
  • HDR UX (Settings, enabling and disabling HDR, power considerations, etc)
  • Dynamic Metadata support
• VRR - Leads: Manasi, Michel
  • State of the art
  • Addressing apps bogging down Mutter
• KMS properties – Leads: Sebastian, Harry Wentland
  • More control over the connector
    • Min/Max BPC
    • YCC support and subsampling
    • Colorspace
    • Compression (DSC)
    • Broadcast RGB, Limited/Full range handling
  • The KMS Color Pipeline
    • Continuing XDC HDR talk/workshop (Harry)
    • How to offload color transformations to the display controller
  • Backlight control (Hans De Goede?)
  • EDID/DisplayID/DDCCI
• Direct scanout on non-compositing GPUs - Leads: Michel, Jonas
  • NVIDIA Advanced Optimus equivalency
  • Use cases and possible gains
  • Missing pieces - KMS APIs, Mutter, driver support, etc.
  • Coming up with a roadmap

• UXD - Leads: AllanDay, JakubSteiner, TobiasBernard

  • Optional, potential separate track to the rest of the event
  • We have a number of shell design topics on the backlog, though whether we’ll be in a position to tackle these in the autumn is unclear

1.2.2. Code of Conduct

As for all GNOME-related events, the GNOME Events Code of Conduct and CodeOfConduct/PhotographyPolicy apply.

Any violations of either should be submitted to the event organizers (see above) or the GNOME Code of Conduct Committee

1.2.3. Timeline

1.2.4. Sponsors

Red Hat will sponsor the Venue and Red Hatters accommodation and travel attending. Additionally, Red Hat will also sponsor the brewery tour and food/drinks in the office. Collabora will sponsor the Monday's dinner.

1.3. Possible Attendees

Additional possible key attendees (add your name in the table above for confirming interest in attendance and edit your relevant contribution)

1.4. Costs

One good option for accommodation close to the venue is: Hotel Vista - which is about €70 night.

Flights from EU around €200 to either Vienna or Prague. Then Student Agency train from any of those cities to Brno around €12.

1.5. How to get there

1.5.1. From Europe or faraway places

• Fly to Vienna or Prague airport

• Direct bus from the airport bus stations to Brno through https://www.studentagency.eu/en/. Reservation required in advance through that website.

• Alternatively, train from those cities to Brno through https://www.studentagency.eu/en/ too.

  • From Vienna airport, you will need to take a regular train to Vienna hbf (main train station a.k.a. hauptbahnhof). The regular train goes every 20 min aprox and tickets can be bought in the Vienna airport machines directly and takes around 30 min travel. Then you can take the Student Agency train to Brno from VIenna hbf.
  • From Prague, you can take a bus to the main train station (a.k.a. Hlavni Nadrazi) through regular city buses in the Prague airport. A ticket can be bought in the yellow colored machines directly in the bus stations of the airport (Czech crown coins required I believe).

1.6. Venue

Red Hat offices, TPB-B. Hosted in the 1st floor, in the Plutonium and Selenium rooms.

You can get to the venue by tram number 12 from the center in "Ceska" tram stop as well as from the main train station "Hlavni Nadrazi", direction Technologicke Park. You can use the PubTram android and ios app to get times for the trams (every 7 min).

1.7. Accommodation and food

Food

QWERTY, Map - 5 min walking from the venue. Relatively small place with lighter Czech food.

Chilli Tree, Map - Reasonable quality and priced Thai food, including vegetarian and vegan options.

Forky's - Excellent modern vegan restaurant in the center. 20 min tram trip from the Venue.

Accomodation

One good option is: Hotel Vista - map - The best way to get to the venue from this hotel is taking bus number 65 in tram stop "Vozovna Medlánky" direction "Technologický park" and get out in the last stop, named "Technologický park", for a total of 7 min. Walking is about 15 min. - directions to the venue.

1.8. Previous discussions, organization threads, drafts, relevant links, etc

<list of any resource like mailing lists, forums, wiki pages, etc where this has been discussed so far>

1.9. Reports

• https://blog.system76.com/post/may-flowers-spring-cosmic-showers

• https://blogs.gnome.org/shell-dev/2023/05/04/vivid-colors-in-brno/

• https://emersion.fr/blog/2023/hdr-hackfest-wrap-up/

• https://wiki.gnome.org/Hackfests/ShellDisplayNext2023?action=AttachFile&do=get&target=HDR+Hackfest.pdf