sdcard: Use dma_protect_rx_region on read operations.

projectgus · projectgus · commit 799356e9011b · 2026-04-23T17:13:31.000+10:00
Will avoid corruption for unaligned reads, unless a SPI DMA operation is in
progress at the same time (to be fixed separately).

This fixes the unit test added in the parent commit.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton &lt;angus@redyak.com.au&gt;
diff --git a/ports/stm32/sdcard.c b/ports/stm32/sdcard.c
@@ -574,7 +574,7 @@ mp_uint_t sdcard_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_blo
 
         // make sure cache is flushed and invalidated so when DMA updates the RAM
         // from reading the peripheral the CPU then reads the new data
-        MP_HAL_CLEANINVALIDATE_DCACHE(dest, num_blocks * SDCARD_BLOCK_SIZE);
+        dma_protect_rx_region(dest, num_blocks * SDCARD_BLOCK_SIZE);
 
         sdcard_reset_periph();
         #if MICROPY_HW_ENABLE_MMCARD
@@ -589,6 +589,8 @@ mp_uint_t sdcard_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_blo
             err = sdcard_wait_finished();
         }
 
+        dma_unprotect_rx_region(dest, num_blocks * SDCARD_BLOCK_SIZE);
+
         #if SDIO_USE_GPDMA
         dma_deinit(&SDMMC_DMA);
         #if MICROPY_HW_ENABLE_MMCARD
