From e35a66879bcc2b28b6b6a82ce395533e3330b088 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Stojke?=
 <100069573+mstojke@users.noreply.github.com>
Date: Thu, 17 Apr 2025 21:05:27 +0200
Subject: [PATCH] Update dma.py

Added argument for _SGDMAChannel.transfer() method to write BD's to selected memory
---
 pynq/lib/dma.py | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/pynq/lib/dma.py b/pynq/lib/dma.py
index 1857149e5..4141cc6c0 100644
--- a/pynq/lib/dma.py
+++ b/pynq/lib/dma.py
@@ -310,7 +310,7 @@ def stop(self):
     def _clear_interrupt(self):
         self._mmio.write(self._offset + 4, 0x1000)
 
-    def transfer(self, array, start=0, nbytes=0, cyclic=False):
+    def transfer(self, array, start=0, nbytes=0, cyclic=False, bd_allocate_target=None):
         """Transfer memory with the DMA
 
         Transfer must only be called when the channel is halted
@@ -345,7 +345,9 @@ def transfer(self, array, start=0, nbytes=0, cyclic=False):
              Number of bytes to transfer. Default is 0.
         cyclic : bool
              Enable cyclic BD mode. Default is False.
-
+        bd_allocate_target : PynqBuffer
+             The target memory to allocate buffer descriptors. Default is None.
+             If None, the buffer descriptors are allocated in the active memory.
         """
 
         if not self.halted:
@@ -377,7 +379,10 @@ def transfer(self, array, start=0, nbytes=0, cyclic=False):
 
         # Zero-Allocate buffer for descriptors: uint32[_num_descr][16]
         # Descriptor is only 52 bytes but each one has to be 64-byte aligned!
-        self._descr = allocate(shape=(self._num_descr, 16), dtype=numpy.uint32)
+        self._descr = allocate(shape=(self._num_descr, 16), dtype=numpy.uint32, target=bd_allocate_target)
+
+        # Fill descriptors with zeros in case of re-use of allocated memory without board reset
+        self._descr.fill(0)
 
         # Idle DMA engine
         self.stop()