drtio: dmb to prevent bursts

src/libboard_artiq/src/drtioaux.rs

@@ -3,6 +3,7 @@ use crc;
 use core_io::{ErrorKind as IoErrorKind, Error as IoError};
 use io::{proto::ProtoRead, proto::ProtoWrite, Cursor};
 use libboard_zynq::{timer::GlobalTimer, time::Milliseconds};
+use libcortex_a9::asm::dmb;
 use crate::mem::mem::DRTIOAUX_MEM;
 use crate::pl::csr::DRTIOAUX;
 use crate::drtioaux_proto::Error as ProtocolError;
@@ -62,10 +63,10 @@ pub fn copy_work_buffer(src: *mut u32, dst: *mut u32, len: isize) {
     // and AXI burst reads/writes are not implemented yet in gateware
     // thus the need for a work buffer for transmitting and copying it over
     unsafe {
-        for i in (0..(len/4)).step_by(2) {
-            //mix offsets to prevent bursts
-            *dst.offset(i+1) = *src.offset(i+1);
+        for i in 0..(len/4) {
             *dst.offset(i) = *src.offset(i);
+            //data memory barrier to prevent bursts
+            dmb();
         }
     }
 }