Graphics

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Graphics Overview

This article will give an overview of how graphics are generated on a rockchip platform.

Graphics with X11

Xserver is the display system used on regular desktop Linux platforms.

Rockchip have a custom Xserver which have enable glamor 2D acceleration.

Xserver usually have a good compatibility, but the performance may be little less and its size is more large than other display system.

Gstreamer X11 sink have DRM 4k-Video render support(though hacky).

Structure

X11 structure in Linux OS

File:X11 structure.png

DDX(armsoc)

source code: git clone git@github.com:markyzq/xf86-video-armsoc.git
maliline: git://anongit.freedesktop.org/xorg/driver/xf86-video-armsoc
The DDX support:

  1. support common x11 display and Hwcursor
  2. DRI2 (request by EGL X11 client)
  3. umplock(support non-tearing on EGL x11 client)

/etc/X11/xorg.conf: Xserver will parse this config to find DDX and configure info

Section "Device"
Identifier  "Mali-Fbdev"
Driver "armsoc"
Option           "UMP_LOCK"   "true"
EndSection
Section "Screen"
Identifier   "Default Screen"
Device       "Mali-Fbdev"
DefaultDepth 24
EndSection

UMPLOCK

source code: wget http://malideveloper.arm.com/downloads/drivers/DX910/r6p1-
01rel0/DX910-SW-99002-r6p1-01rel0.tgz
Patch the umplock patch to kernel, then you can find the umplock device node:

/dev/umplock

Don't forget enable DDX umplock option:

Option           "UMP_LOCK"   "true"

The umplock only use for x11 graphic stack, no need for wayland, because mali 
already do the wayland sync on its driver.

X11 performance Test

2D performace:

x11perf

3D preformace:

glmark2-es2

X11perf tools can easy get from x11-apps.
glmark2-es2 can get from https://github.com/glmark2/glmark2
The glmark2-es2 source code can also build for x11, drm(gbm) and wayland.

Graphics with Wayland

Weston is the reference implementation of a Wayland compositor, and a
useful compositor in its own right.

Rockchip don't do much develop in wayland at current, but wetson are tested that can run in rk3288 and rk3399.

Graphics with None

If you don't want to use X11 or wayland, there are some chooses for you.

Interface:
Libdrm and libmali-gbm can be used to draw UI without display systems.

Framework:
QT can work without x11 or wayland, it run Qt5 applications on top of EGL(libmali-gbm).
WIth qt eglfs, video player can reach 1080-60fps.

GPU Performance

Test platform: rk3288

backend off-screen on-screen DMA-Buf
X11     support
Wayland     support
gbm     support
fbdev untested untested unsupport

Others

For details of the full Linux graphics stack, please refer to online documents in FreedesktopARMArch wiki…..