Targeting the VideoCore IV GPU on RPi

[obutk]

Is it possible to use the Videocore IV hardware when developing programs in tinycore? I have to perform image processing on the RPi, and I thought maybe I could get some speed boost by targeting the GPU.

I have tried using two C/C++ libraries for creating programs to run on the VideoCore GPU. While I was able to compile them, they always fail at runtime (segfault or a generic error).

For reference, these are the libraries I've tried:
https://github.com/wimrijnders/V3DLib
https://github.com/doe300/VC4CL

Is there any kind of configuration (bootcode or config.txt) or package that I should be using to make this possible?

[Juanito]

I played around with gpu hardware acceleration using piCore64 on an RPi4 - I believe this is VideoCore VI.

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glxinfo | grep -i gpu
    GL_EXT_gpu_program_parameters, GL_EXT_gpu_shader4,
..and this plays a video using hardware acceleration:

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ffplay -i test_video.mp4 -vcodec h264_v4l2m2m
If you let me know how you tested https://github.com/wimrijnders/V3DLib I can give it a try although it might not be relevent to VideoCore IV...

[gadget42]

fascinating:

https://github.com/wimrijnders/V3DLib/blob/main/Doc/Basics.md

sharing is caring

[Juanito]

I built v3dlib on piCore64 - all the tests pass and ./obj/qpu-debug/bin/GCD runs.

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sudo ./obj/qpu-debug/bin/detectPlatform
Platform    : Raspberry Pi 4 Model B Rev 1.4
Model Number: BCM2711
Revision    : d03114
This is a pi platform.
GPU: v3d (VideoCore VI)


[Juanito]

On piCore/RPi3 several of the tests fail with:

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FATAL: Failed to allocate vc4 shared  memory..but that might be addressed with something in config.txt

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sudo ./obj/qpu-debug/bin/detectPlatform
Platform    : Raspberry Pi 3 Model B Rev 1.2
Model Number: BCM2837
Revision    : a02082
This is a pi platform.
GPU: vc4 (VideoCore IV)


[obutk]

If you let me know how you tested https://github.com/wimrijnders/V3DLib I can give it a try although it might not be relevent to VideoCore IV...

I'm using a RPi02W (armv7) with PiCore 13.

My cmdline.txt:

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zswap.compressor=lz4 zswap.zpool=z3fold console=tty0 root=/dev/ram0 elevator=deadline rootwait quiet nortc loglevel=3 noembed

My onboot.lst: https://pastebin.com/VkBcqcUJ

My config.txt: https://pastebin.com/5nVHnVui

Here is what I did. Loading the programming packages:

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#loading general programming packages
tce-load -i compiletc git
#loading specific packages used by V3DLib
tce-load -i expat2-dev rpi-vc-dev

Then I cloned V3DLib and its dependency CmdParameter, and I applied the change described in https://github.com/wimrijnders/V3DLib/issues/7

Compiling:

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#compiling CmdParameter
cd CmdParameter
make DEBUG=1 all
cd ..
#compiling V3DLib and running the tests (all tests fail)
cd V3DLib
make QPU=1 DEBUG=1 test
#running the tests as root (to see if there is any difference. also fail)
sudo su
./obj/qpu-debug/bin/runTests

Here are the results of the tests: https://pastebin.com/uqbZWLhc

detectPlatform seems to work:

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sudo ./obj/qpu-debug/bin/detectPlatform
Platform    : Raspberry Pi Zero 2 W Rev 1.0
Model Number: BCM2837
Revision    : 902120
This is a pi platform.
GPU: vc4 (VideoCore IV)


[Juanito]

Do you need graphics-KERNEL loaded and the following in config.txt:

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[PI02]
dtoverlay=vc4-kms-v3d
..maybe also rpi-vc?

[obutk]

Do you need graphics-KERNEL loaded and the following in config.txt:

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[PI02]
dtoverlay=vc4-kms-v3d
..maybe also rpi-vc?

I tried adding:

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graphics-5.10.77-piCore-v7.tcz
rpi-vc.tcz
at the top of my onboot.lst file, and:

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dtoverlay=vc4-kms-v3d
gpu_mem=256
at the bottom of my config.txt.

The "ioctl_set_msg failed: -1" error message and memory allocation problems seem to have disappeared, but the tests are still failing:

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ERROR: test case THREW exception: FATAL: Unable to enable QPUs. Check your firmware is latest.


[Juanito]

After adding gpu_mem=128 I get the same firmware error on the RPi3/piCore.

On the RPi4/piCore64 all tests pass.

Maybe you could report it as an issue at https://github.com/wimrijnders/V3DLib/issues

[obutk]

Maybe you could report it as an issue at https://github.com/wimrijnders/V3DLib/issues

I think it is a good idea, but first it would nice to test it with Raspbian 10 Buster to verify if this issue is not related to tinycore. E.g. maybe graphics-KERNEL.tcz or rpi-vc.tcz could be updated? I'm gonna try it with my Pi if I have some time.