tst: add regression test for 4Byte corruption

Problem: sometimes a 4Byte transfers corrupt the gennum chip Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

tst: add regression test for 4Byte corruption
Problem: sometimes a 4Byte transfers corrupt the gennum chip Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
a108596a · Federico Vaga · 6d9fec0e · a108596a
Commit a108596a authored Jul 02, 2020 by Federico Vaga
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test_dma.py pytest/test_dma.py +17 -0

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--- a/pytest/test_dma.py
+++ b/pytest/test_dma.py
@@ -206,3 +206,20 @@ class TestDma(object):
            dma.write(0, data)
            for i in range(1000000):
                assert data == dma.read(0, len(data))
+
+    def test_dma_reg_word(self, spec):
+        """
+        Regression test.
+        It happend that a 4Bytes transfer was triggering a DMA error
+        and in some cases it was irremediably corrupting the gennum chip
+        """
+        data = b"\x01\x23\x45\x67\x89\xab\xcd\xef"
+        with spec.dma() as dma:
+            dma.write(0, data)
+            for i in range(1000000):
+                try:
+                    data_rb = dma.read(0, 4)
+                except OSError as error:
+                    assert data == dma.read(0, 8)
+                finally:
+                    assert data[0:4] == data_rb