[sw, otbn] Acknowledge Done interrupt in ECDSA P-256 test
Previously, we weren't clearing the state of the Done interrupt after
handling it. As a result, a false interrupt could get signaled
immediately after re-enabling it during the execution of the next
OTBN program which led Ibex to read out DMEM while OTBN was still busy
causing a fatal alert and test failures.
Signed-off-by: Pirmin Vogel <vogelpi@lowrisc.org>
diff --git a/sw/device/tests/otbn_ecdsa_op_irq_test.c b/sw/device/tests/otbn_ecdsa_op_irq_test.c
index ac61d87..01abf10 100644
--- a/sw/device/tests/otbn_ecdsa_op_irq_test.c
+++ b/sw/device/tests/otbn_ecdsa_op_irq_test.c
@@ -168,6 +168,9 @@
// Disable Done interrupt.
CHECK_DIF_OK(dif_otbn_irq_set_enabled(&otbn_ctx->dif, kDifOtbnIrqDone,
kDifToggleDisabled));
+
+ // Acknowledge Done interrupt. This clears INTR_STATE.done back to 0.
+ CHECK_DIF_OK(dif_otbn_irq_acknowledge(&otbn_ctx->dif, kDifOtbnIrqDone));
}
static void otbn_init_irq(void) {
