Fix DVI blanking during SPI transactions #10598
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SPI was using DMA to transfer to PSRAM. When a cache miss occurs, the DMA can't switch to another transfer and throws off DVI timing. So, only use DMA with SPI when the buffers are in SRAM. This will slow down SPI transactions when the FIFOs are empty and the CPU is busy running a background task. It will still be correct though since we control the SPI clock. Fixes micropython#10557
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I've tested with my Weather Clock and that no longer blinks while it's performing the web requests. I had also seen the blinking when playing MP3 files from the SD card and this seems to have resolved that as well. |
dhalbert
approved these changes
Aug 29, 2025
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SPI was using DMA to transfer to PSRAM. When a cache miss occurs, the DMA can't switch to another transfer and throws off DVI timing.
So, only use DMA with SPI when the buffers are in SRAM. This will slow down SPI transactions when the FIFOs are empty and the CPU is busy running a background task. It will still be correct though since we control the SPI clock.
Fixes #10557