1.
https://www.pengutronix.de
Making embedded less special
With open-source graphics drivers
Lucas Stach – l.stach@pengutronix.de

2.
2/27
About me

Linux kernel and graphics infrastructure hacker at
Pengutronix

Maintainer of the Etnaviv kernel driver

Involved with a bunch of other Linux kernel stuff

3.
3/27
Motivation

How are open-source drivers helping to make the
embedded space less special?

How does it all fit together?

4.
4/27
Scope
Nothing but graphics generation and output

5.
5/27
Key-/Buzzwords

OpenGL

Vulkan

KMS

6.
6/27
Key-/Buzzwords

OpenGL

Accelerated graphics API

Vulkan

Low-level accelerated graphics API

KMS

Kernel ModeSetting

7.
7/27
The situation a few years ago

Fat, but GPL compliant kernel drivers

Large, closed source binary userspace libraries

Lots of special, non-standardized interfaces

8.
8/27
Linux kernel DRM subsystem

Direct Rendering Manager

NOT Digital Rights Management

Standardized interface for display hardware (KMS)

Custom IOCTL interface for graphics accelerators

9.
9/27
Linux kernel DRM subsystem
Display driver Accelerator driver
KMS IOCTLs Kernel
Userspace

10.
10/27
Linux kernel DRM subsystem

Why a custom interface for each GPU?

Graphics APIs are huge → not possible to implement in
kernelspace

(Not so) Subtle differences in how the hardware works

11.
11/27
Mesa – swiss army knife of graphics APIs

Implementations for all kinds of graphics APIs

OpenGL

Vulkan

OpenCL

GPU hardware drivers

12.
12/27
Mesa – swiss army knife of graphics APIs
Display driver Accelerator driver
KMS IOCTLs Kernel
Userspace
Mesa
OpenGLEGL

13.
13/27
Mesa – swiss army knife of graphics APIs
Gallium Interface
DRI2 state tracker OpenGL state tracker
radeonsi iris panfrost etnaviv

14.
14/27
Mesa – swiss army knife of graphics APIs

Some numbers:

imx-drm kernel driver: ~3 kLoc

etnaviv kernel driver: ~9 kLoc

etnaviv userspace driver: ~20 kLoc

15.
15/27
Mesa – swiss army knife of graphics APIs

Some numbers:

imx-drm kernel driver: ~3 kLoc

etnaviv kernel driver: ~9 kLoc

etnaviv userspace driver: ~20 kLoc

OpenGL state tracker: ~400 kLoc

16.
16/27
Mesa – swiss army knife of graphics APIs
Gallium Interface
DRI2 state tracker OpenGL state tracker
radeonsi iris panfrost etnaviv

17.
17/27
Mesa – swiss army knife of graphics APIs
Display driver Accelerator driver
KMS IOCTLs Kernel
Userspace
Mesa
OpenGLEGL/GBM

18.
18/27
Mesa – swiss army knife of graphics APIs
Display driver Accelerator driver
KMS IOCTLs Kernel
Userspace
Mesa
OpenGLEGL/GBM
Qt5 EGLFS

19.
19/27
Wayland

But that‘s still special, isn‘t it?

What if I want more than a single application?

20.
20/27
Wayland
Display driver Accelerator driver
KMS IOCTLs Kernel
Userspace
Mesa
OpenGLEGL/
GBM
Compositor
OpenGLEGL/
Wayland
Qt5 Wayland
Wayland

21.
21/27
Wayland

No platform specific code at the application side

Policy can be implemented in a single place

This is like your modern Linux desktop!

22.
https://www.pengutronix.de
Questions?

23.
23/27
Current state - Freedreno

Stable, featureful driver

Supports most Adreno GPU cores

Google investing in development

24.
24/27
Current state - Etnaviv

Stable GL ES2.0 support

Supports latest available GPU generation

Multiple commercial users investing in development

25.
25/27
Current state - Lima

Merged into upstream projects

AFAIK mostly a hobby project

Supports older generation Mali GPUs

26.
26/27
Current state - Panfrost

Fast-paced feature work

Strong developer community

Newer Mali GPUs supported

27.
https://www.pengutronix.de
Thanks!