Fix ESP32-S2 SPI when DMA is sometimes used

tannewt · tannewt · commit 95cb5961d26a · 2020-10-26T16:59:59.000-07:00
diff --git a/ports/esp32s2/common-hal/busio/SPI.c b/ports/esp32s2/common-hal/busio/SPI.c
@@ -357,6 +357,9 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, const uint8_t *data_ou
     } else {
         hal->dma_enabled = 0;
         burst_length = sizeof(hal->hw->data_buf);
+        // When switching to non-DMA, we need to make sure DMA is off. Otherwise,
+        // the S2 will transmit zeroes instead of our data.
+        spi_ll_txdma_disable(hal->hw);
     }
 
     // This rounds up.

Original file line number	Diff line number	Diff line change
`@@ -357,6 +357,9 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t self, const uint8_t data_ou`
`357`	`357`	`} else {`
`358`	`358`	`hal->dma_enabled = 0;`
`359`	`359`	`burst_length = sizeof(hal->hw->data_buf);`
	`360`	`+ // When switching to non-DMA, we need to make sure DMA is off. Otherwise,`
	`361`	`+ // the S2 will transmit zeroes instead of our data.`
	`362`	`+ spi_ll_txdma_disable(hal->hw);`
`360`	`363`	`}`
`361`	`364`
`362`	`365`	`// This rounds up.`