mirror of
https://github.com/Yours3lf/rpi-vk-driver.git
synced 2024-12-05 17:24:14 +01:00
128 lines
4.8 KiB
Markdown
128 lines
4.8 KiB
Markdown
# rpi-vk-driver
|
|
(not conformant yet, can't use official name or logo)
|
|
|
|
## Milestones
|
|
- [x] clear screen example working
|
|
- [x] triangle example working
|
|
- [x] shader from assembly, vertices from vertex buffer object, no uniforms, color hardcoded
|
|
- [x] uniforms for matrix multiplication and animation
|
|
- [x] texture coordinates and texture sampling
|
|
- [x] varyings
|
|
- [x] Multiple vertex attributes
|
|
- [x] Depth buffers
|
|
- [x] Stencil buffers
|
|
- [x] Indexed draw calls
|
|
- [x] blending
|
|
- [ ] mipmapping
|
|
- [x] Shader compiler chain
|
|
- [x] QPU assembler / disassembler
|
|
- [x] Resources
|
|
- [x] Descriptor support
|
|
- [x] VkSampler support
|
|
- [x] Push constant support
|
|
- [x] Platform features
|
|
- [x] Layer support
|
|
- [ ] Emulated features
|
|
- [ ] Clear command support
|
|
- [ ] Copy command support
|
|
- [ ] Render to texture features
|
|
- [ ] VkRenderPass support
|
|
- [ ] Subpass support
|
|
- [ ] Multiple attachments
|
|
- [ ] MSAA support
|
|
- [ ] Synchronization
|
|
- [ ] vkCmdPipelineBarrier support
|
|
- [ ] Performance
|
|
- [ ] Performance counters
|
|
- [ ] Queries
|
|
- [ ] Shader performance info
|
|
- [ ] WSI
|
|
- [ ] Direct to display support
|
|
- [ ] Secondary command buffers
|
|
- [ ] Fixes
|
|
- [ ] Hardware bug workarounds
|
|
- [ ] Handle offsets wherever required
|
|
- [ ] Handle subresource ranges properly
|
|
- [ ] Handle allocation scopes properly
|
|
- [ ] Shader module creation might not be thread safe
|
|
- [ ] Try to pass as much of the VK CTS as possible with existing feature set
|
|
- [ ] Github pages
|
|
- [ ] Wiki
|
|
- [ ] Performance recommendations
|
|
- [ ] How to do blending, depth/stencil testing, attributes
|
|
|
|
## VK CTS progress
|
|
- Passed: 7894/67979 (11.6%)
|
|
- Failed: 878/67979 (1.3%)
|
|
- Not supported: 59206/67979 (87.1%)
|
|
- Warnings: 1/67979 (0.0%)
|
|
|
|
Conformance run is considered passing if all tests finish with allowed result
|
|
codes.
|
|
Following status
|
|
codes are allowed:
|
|
|
|
- Pass
|
|
- NotSupported
|
|
- QualityWarning
|
|
- CompatibilityWarning
|
|
|
|
There are about 470.000 conformance tests.
|
|
|
|
## FAQ
|
|
### Will this ever be a fully functional VK driver?
|
|
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.
|
|
|
|
### 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.
|
|
CPU performance (eg. number of draw calls) should be enough on the quad-core PIs as you can easily utilise all cores using VK.
|
|
|
|
### 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
|
|
- instancing
|
|
- some vertex buffer formats
|
|
- pipeline caches (doesn't make sense with assembly shaders)
|
|
|
|
### What additional features will this driver support?
|
|
- 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.
|
|
- Videocore IV provides some performance counters these will be exposed
|
|
- Videocore IV supports some texture formats that are not present in the spec
|
|
- bw1: 1 bit black and white
|
|
- a4: 4 bit alpha
|
|
- a1: 1 bit alpha
|
|
- vector graphics support?
|
|
|
|
### Shader patching
|
|
The Broadcom Videocore IV needs a couple of operations to happen in shader code that might have fixed function hardware on other platforms.
|
|
These are:
|
|
- writing stencil state setup register
|
|
- writing depth value to depth buffer
|
|
- performing blending in software
|
|
- writing vertex parameter memory read and write setup registers
|
|
|
|
Since the project will not include a compiler, but rather works with an assembly based shader setup, I decided not to patch shaders based on the state provided to the driver, but rather let the developer have full control.
|
|
This means that regardless of what
|
|
- depth write state
|
|
- blending state
|
|
- stencil state
|
|
- vertex attribute state
|
|
|
|
is passed to the driver, this will not be reflected in the final behaviour unless the developer adds it to the assembly shaders.
|
|
Helper functionality will be provided to aid with encoding register values. Additionally, general documentation will be provided on how to perform these operations.
|
|
|
|
This will enable developers to take full control and optimise shaders to the last cycle.
|
|
|