diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/CNN_TEST_TOOL.md | 37 | ||||
| -rw-r--r-- | doc/HOWTO.md | 3 |
2 files changed, 34 insertions, 6 deletions
diff --git a/doc/CNN_TEST_TOOL.md b/doc/CNN_TEST_TOOL.md index 09c55d4..e7d679e 100644 --- a/doc/CNN_TEST_TOOL.md +++ b/doc/CNN_TEST_TOOL.md @@ -178,12 +178,37 @@ assert mse < 10.0, f'MSE too high: {mse}' ## Known Issues -**BUG: Black output (unknown cause)** -- Tool produces all-black output despite correct architecture -- Fixed ping-pong logic, RGBA16Float intermediates, proper pipelines -- Shader compiles, GPU commands execute without errors -- Possible causes: shader execution issue, synchronization, binding problem -- Status: Under investigation +**BUG: CNN produces incorrect output (all white)** +- Readback works correctly (see Technical Notes below) +- Shader compiles and executes without errors +- Output is all white (255) regardless of input or blend setting +- **Likely causes:** + - Uniform buffer layout mismatch between C++ and WGSL + - Texture binding issue (input not sampled correctly) + - Weight matrix initialization problem +- CNNEffect works correctly in demo (visual validation confirms) +- **Status:** Under investigation - rendering pipeline differs from demo's CNNEffect +- **Workaround:** Use CNNEffect visual validation in demo until tool fixed + +--- + +## Technical Notes (Readback Fix) + +**Original Bug:** Buffer mapping returned `WGPUMapAsyncStatus_Unknown` (status=5) + +**Root Cause:** Callback mode mismatch +- Used `WGPUCallbackMode_WaitAnyOnly` (fires only during `wgpuInstanceWaitAny`) +- Called `wgpuInstanceProcessEvents` in wait loop (wrong API for this mode) +- Callback never fired → timeout → empty buffer + +**Fix Applied:** +1. Changed callback mode to `WGPUCallbackMode_AllowProcessEvents` +2. Replaced `wgpuInstanceProcessEvents` with `wgpuDevicePoll(device, true, nullptr)` +3. Added pre-mapping device poll to ensure copy completes + +**Relevant Code:** `src/gpu/texture_readback.cc` lines 97-110 + +**Reference:** WebGPU spec - Asynchronous Operations, Callback Modes --- diff --git a/doc/HOWTO.md b/doc/HOWTO.md index c0e9363..140c09f 100644 --- a/doc/HOWTO.md +++ b/doc/HOWTO.md @@ -165,6 +165,9 @@ See `doc/ASSET_SYSTEM.md` and `doc/WORKSPACE_SYSTEM.md`. ## CNN Testing ### Offline Shader Validation + +**Note:** Tool builds and runs but produces incorrect output. Use CNNEffect visual validation in demo. See `doc/CNN_TEST_TOOL.md`. + ```bash # Test trained CNN on PNG input ./build/cnn_test input.png output.png |