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Graphics Driver Framework

Overall Framework​

Linux Graphical Framework

Environment Setup and Dependencies​

Kernel​

Enter the Linux Kernel source directory and enable PowerVR GPU driver in the config:

CONFIG_POWERVR_ROGUE=y # Enable PowerVR Rogue

You can also enable it through make menuconfig in the graphical interface.
Navigate to Device Drivers -> Graphics support -> PowerVR GPU, and select the PowerVR GPU option:

<*>   Lontium LT9711 DSI to DP
< > null drm disp
<*> PowerVR GPU # Enable PowerVR GPU
[ ] Enable legacy drivers (DANGEROUS)  ----
    Frame buffer Devices  --->

PVR DDK​

Due to copyright restrictions, the DDK (Device Development Kit) for the PVR GPU cannot be provided directly.
User-space closed-source code is provided as shared libraries (.so) offering OpenGLES, Vulkan, and OpenCL APIs.

The way to enable the PVR GPU driver on bianbu-linux and bianbu-desktop is as follows:

bianbu-linux​

Enable it in the configuration file when compiling Buildroot:

BR2_PACKAGE_IMG_GPU_POWERVR=y

Or manually select it via make menuconfig: External options -> Bianbu config -> img-gpu-powervr

[*] rtk hciattach
    *** spacemit mpp package ***
-*- spacemit mpp
[*] img-gpu-powervr # Enable `img-gpu-powervr`
    Output option (Wayland)  --->
[ ]   install examples

bianbu-desktop​

Due to licensing issues, the closed-source GPU code is provided as .so shared libraries via the img-gpu-powervr .deb package.
Users can install the PVR GPU driver with:

sudo apt install img-gpu-powervr

Note: The GPU driver consists of a kernel-level driver and a user-level driver; both must have matching versions, otherwise GPU functionality may be abnormal.

Method to check the version:

  # Check the kernel-level driver
  ➜  ~ journalctl -b | grep "Initialized pvr"
  11月 21 14:11:37 spacemit-k1-x-MUSE-Pi-board kernel: [drm] Initialized pvr 24.2.6603887 20170530 for cac00000.imggpu on minor 1 # Version 24.2
  # Check the user-level driver
  ➜  ~ dpkg -s img-gpu-powervr
  Package: img-gpu-powervr
  Status: install ok installed
  Priority: optional
  Section: graphics
  Installed-Size: 70314
  Maintainer: bianbu <bo.deng@spacemit.com>
  Architecture: all
  Version: 24.2-6603887bb1 # Version 24.2

Mesa3D​

Mesa3D provides the OpenGL ES API interface and software rendering implementation.

It bridges applications that use OpenGL ES APIs with the underlying PowerVR GPU driver.

bianbu-linux​

Enable the following options in the configuration file to activate Mesa3D:

  Symbol: BR2_PACKAGE_MESA3D [=y]
  Symbol: BR2_PACKAGE_MESA3D_DRIVER [=y] 
  Symbol: BR2_PACKAGE_MESA3D_GALLIUM_DRIVER [=y]
  Symbol: BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_PVR [=y]
  Symbol: BR2_PACKAGE_MESA3D_GBM [=y]
  Symbol: BR2_PACKAGE_MESA3D_OPENGL_EGL [=y]

Or manually select from make menuconfig: Target packages -> Graphic libraries and applications -> mesa3d

  -*-   Gallium pvr driver
  *** Gallium VDPAU state tracker needs X.org and gallium drivers r300, r600, radeonsi or nouveau ***
  *** Vulkan drivers ***
  *** Off-screen Rendering ***
  [ ]   OSMesa (Gallium) library
        *** OpenGL API Support ***
  -*-   gbm
  *** OpenGL GLX support needs X11 ***
  -*-   OpenGL EGL
  [ ]   OpenGL ES

bianbu-desktop​

Calling the PowerVR GPU hardware depends on the Mesa .deb packages from the bianbu source, which should be installed in the following order:

      "libgl1-mesa-dev_*_riscv64.deb"
      "libegl1-mesa_*_riscv64.deb"
      "libegl1-mesa-dev_*_riscv64.deb"
      "libglapi-mesa_*_riscv64.deb"
      "libgbm1_*_riscv64.deb"
      "libgbm-dev_*_riscv64.deb"
      "libegl-mesa0_*_riscv64.deb"
      "libgl1-mesa-dri_*_riscv64.deb"
      "libgles2-mesa_*_riscv64.deb"
      "libgles2-mesa-dev_*_riscv64.deb"
      "libgl1-mesa-glx_*_riscv64.deb"
      "libglx-mesa0_*_riscv64.deb"
      "libosmesa6_*_riscv64.deb"
      "libosmesa6-dev_*_riscv64.deb"
      "libwayland-egl1-mesa_*_riscv64.deb"
      "mesa-common-dev_*_riscv64.deb"

Also need to install libglvnd:

  sudo apt install libglvnd

Others​

BlobCache Usage​

The GPU BlobCache is a data caching mechanism used to store and reuse GPU compilation results.
This caching mechanism aims to improve performance by reducing redundant computations and data transfers, thereby speeding up rendering.

Configuration Method

  1. Open the configuration file:

    vim /etc/powervr.ini

  2. Set as follows to enable the BlobCache feature:

[default]
EnableBlobCache=1 # Enable the BlobCache feature

[mpv]
EnableWorkaroundMPVScreenTearing=1

[totem]
EnableWorkaroundMPVScreenTearing=1

[gst-launch-1.0]
EnableWorkaroundMPVScreenTearing=1

3.2 GPU Node Debugging​

By monitoring the GPU node, you can view the GPU’s running status in real time:

~ su
~ cd /sys/kernel/debug/pvr/
~ watch cat status (Press Ctrl+C to exit)

Example output as shown below：

Every 2.0s: cat status                                    spacemit-k1-x-deb1-board: Thu Nov 28 09:00:00 2024

Driver Status:   OK

Device ID: 0:128
Firmware Status: OK
Server Errors:   24
HWR Event Count: 0
CRR Event Count: 0
SLR Event Count: 0
WGP Error Count: 0
TRP Error Count: 0
FWF Event Count: 0
APM Event Count: 0
GPU Utilisation: 0%
DM Utilisation:  VM0
           2D:   0%
         GEOM:   0%
           3D:   0%
          CDM:   0%
          RAY:   0%
        GEOM2:   0%