Commit 6d9fec0e authored by Federico Vaga's avatar Federico Vaga

tst: add regression test for zero bytes

Problem: after Xbytes the DMA read returns only zeros. This happens at
a power-of-two offset, typically below 1024
Signed-off-by: Federico Vaga's avatarFederico Vaga <>
parent 6a86876a
......@@ -193,3 +193,16 @@ class TestDma(object):
dma.write(ddr_offset, data)
data_rb =, buffer_size)
assert data == data_rb
def test_dma_reg_zero(self, spec):
Regression test.
It happend that after 256Bytes the received data is just
0x00. Other times it happend at different sizes but always
among the first power of two values
data = bytes([random.randrange(0, 0xFF, 1) for i in range(1024)])
with spec.dma() as dma:
dma.write(0, data)
for i in range(1000000):
assert data ==, len(data))
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