mimxrt/machine_sdcard: Fix buffer type in writeblocks.

The writeblocks function was requesting the buffer as MP_BUFFER_WRITE
when it should be MP_BUFFER_READ, since we read FROM the buffer to
write TO the card. This was preventing VFS operations like mkfs and
mount from working, as FatFS passes const buffers for write operations.

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

Author: pi-anl

ports/mimxrt/machine_sdcard.c

@@ -142,7 +142,7 @@ static MP_DEFINE_CONST_FUN_OBJ_1(machine_sdcard_info_obj, machine_sdcard_info);
 static mp_obj_t machine_sdcard_writeblocks(mp_obj_t self_in, mp_obj_t block_num, mp_obj_t buf) {
     mp_buffer_info_t bufinfo;
     mimxrt_sdcard_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_WRITE);
+    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_READ);
 
     if (sdcard_write(self, bufinfo.buf, mp_obj_get_int(block_num), bufinfo.len / SDCARD_DEFAULT_BLOCK_SIZE)) {
         return MP_OBJ_NEW_SMALL_INT(0);