pub fn assert_dma_capable(buf: &[u8])Expand description
Debug-assert that buf is DMA-reachable on this chip.
On the ESP32 (Fire27) the DMA engine cannot reach the PSRAM-mapped data
window, so a PSRAM-backed buffer handed to SPI/I2S DMA silently corrupts.
This catches that on first use under debug_assertions. It is a no-op
(compiled away) on the ESP32-S3, which can DMA from PSRAM.