diff --git a/ports/raspberrypi/common-hal/busio/SPI.c b/ports/raspberrypi/common-hal/busio/SPI.c index d20bc4d7d10aa..4735d1284f98e 100644 --- a/ports/raspberrypi/common-hal/busio/SPI.c +++ b/ports/raspberrypi/common-hal/busio/SPI.c @@ -182,7 +182,10 @@ static bool _transfer(busio_spi_obj_t *self, chan_tx = dma_claim_unused_channel(false); chan_rx = dma_claim_unused_channel(false); } - bool use_dma = chan_rx >= 0 && chan_tx >= 0; + bool has_dma_channels = chan_rx >= 0 && chan_tx >= 0; + // Only use DMA if both data buffers are in SRAM. Otherwise, we'll stall the DMA with PSRAM or flash cache misses. + bool data_in_sram = data_in >= (uint8_t *)SRAM_BASE && data_out >= (uint8_t *)SRAM_BASE; + bool use_dma = has_dma_channels && data_in_sram; if (use_dma) { dma_channel_config c = dma_channel_get_default_config(chan_tx); channel_config_set_transfer_data_size(&c, DMA_SIZE_8);