2018-08-03 17:06:01 +02:00
# rpi-vk-driver
(not conformant yet, can't use official name or logo)
2018-08-26 15:49:21 +02:00
## Milestones
- [x] clear screen example working
2018-10-14 18:29:57 +02:00
- [x] triangle example working
- [x] shader from assembly, vertices from vertex buffer object, no uniforms, color hardcoded
2019-08-25 20:03:04 +02:00
- [x] uniforms for matrix multiplication and animation
- [x] texture coordinates and texture sampling
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- [x] varyings
- [x] Multiple vertex attributes
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- [x] Depth buffers
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- [x] Stencil buffers
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- [x] Indexed draw calls
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- [x] blending
2019-07-05 22:19:59 +02:00
- [x] Shader compiler chain
2019-07-05 21:53:50 +02:00
- [x] QPU assembler / disassembler
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- [x] Resources
- [x] Descriptor support
- [x] VkSampler support
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- [x] Push constant support
2019-10-02 01:09:53 +02:00
- [x] Platform features
- [x] Layer support
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- [ ] Render to texture features
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- [ ] VkRenderPass support
- [ ] Subpass support
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- [ ] Multiple attachments
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- [ ] MSAA support
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- [ ] Synchronization
- [ ] vkCmdPipelineBarrier support
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- [ ] Performance
- [ ] Performance counters
- [ ] Queries
- [ ] Shader performance info
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- [ ] Emulated features
- [ ] Clear command support
- [ ] Copy command support
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- [ ] Shader patching
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- [x] Stencil state
- [x] Depth writes
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- [ ] Blending mode
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- [ ] Vertex attrib format
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- [ ] WSI
- [ ] Direct to display support
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- [ ] Secondary command buffers
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- [ ] Try to pass as much of the VK CTS as possible with existing feature set
2019-07-05 22:19:59 +02:00
2018-11-17 16:57:20 +01:00
## VK CTS progress
2019-02-09 17:20:14 +01:00
- Passed: 7894/67979 (11.6%)
- Failed: 878/67979 (1.3%)
- Not supported: 59206/67979 (87.1%)
- Warnings: 1/67979 (0.0%)
2018-11-17 17:39:13 +01:00
2019-02-09 17:24:29 +01:00
Conformance run is considered passing if all tests finish with allowed result
codes.
Following status
codes are allowed:
- Pass
- NotSupported
- QualityWarning
- CompatibilityWarning
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There are about 470.000 conformance tests.
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## FAQ
### Will this ever be a fully functional VK driver?
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As far as I know the PI is NOT fully VK capable on the hardware level. I can already see that some things will need to be emulated and others won't ever be emulated.
2018-11-17 17:39:13 +01:00
### What performance should you expect?
Performance wise, the Pi is quite capable. The specs and architecture is close to the GPU in the iPhone 4s. The only problem I see is bandwidth as you only have about 7GB/s compared to 12-25GB/s on typical mobile phones. So post processing is a huge no and you'd need to be very careful about the techniques that you use. Eg. you'd need to stay on chip at all times.
2018-11-17 17:39:36 +01:00
CPU performance (eg. number of draw calls) should be enough on the quad-core PIs as you can easily utilise all cores using VK.
2018-11-17 17:39:13 +01:00
2019-09-15 16:14:09 +02:00
### What features will not be supported?
- 3D textures
- sparse textures
- compute shaders (though could be supported to some extent if the kernel side would support it)
- some texture formats
- some render target texture formats
- occlusion queries (https://github.com/anholt/mesa/wiki/VC4-OpenGL-support)
- indirect draws
- spirv shaders
- events
- proper semaphore support
- tessellation shaders
- geometry shaders
- 32 bit indices
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- instancing
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- some vertex buffer formats
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- pipeline caches (doesn't make sense with assembly shaders)
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### What additional features will this driver support?
2018-11-17 17:39:13 +01:00
- I already added support (to be polished) to load shader assembly. This will enable devs to optimise shaders to the last cycle.
- I'll probably add something to indicate towards the developer that things are emulated or not supported at all.
2019-09-15 16:14:09 +02:00
- Videocore IV provides some performance counters these will be exposed
- Videocore IV supports some texture formats that are not present in the spec
2019-09-15 18:34:55 +02:00
- bw1: 1 bit black and white
- a4: 4 bit alpha
- a1: 1 bit alpha
- vector graphics support?
