mimxrt/sdcard: Add cache coherency operations for DMA transfers.

Add explicit data cache management to ensure DMA transfers work correctly
on systems with data cache enabled (e.g., MIMXRT1170).

For reads: Clean and invalidate cache before transfer so DMA can update
RAM and CPU reads fresh data.

For writes: Clean cache to RAM before transfer so DMA reads correct data.

This follows the same pattern as ports/stm32/sdcard.c which uses
MP_HAL_CLEANINVALIDATE_DCACHE for reads and MP_HAL_CLEAN_DCACHE for writes.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

ports/mimxrt/sdcard.c

@@ -869,6 +869,10 @@ bool sdcard_read(mimxrt_sdcard_obj_t *card, uint8_t *buffer, uint32_t block_num,
         return false;
     }
 
+    // Ensure cache is flushed and invalidated so when DMA updates RAM
+    // from the peripheral, the CPU reads the new data.
+    MP_HAL_CLEANINVALIDATE_DCACHE(buffer, block_count * card->block_len);
+
     usdhc_data_t data = {
         .enableAutoCommand12 = true,
         .enableAutoCommand23 = false,
@@ -908,6 +912,9 @@ bool sdcard_write(mimxrt_sdcard_obj_t *card, uint8_t *buffer, uint32_t block_num
         return false;
     }
 
+    // Ensure cache is flushed to RAM so DMA can read the correct data.
+    MP_HAL_CLEAN_DCACHE(buffer, block_count * card->block_len);
+
     usdhc_data_t data = {
         .enableAutoCommand12 = true,
         .enableAutoCommand23 = false,