From: YannickV <Y.Vossen@beckhoff.com>

During the emulation startup, all registers are reset, which triggers the
`r_unlock_post_write` function with a value of 0. This led to an
unintended memory access disable, making the devcfg unusable.

To address this, a property 'is_initialized' is introduced. It is set
to false during reset and updated to true once the initialization is
complete. The unlock function is simply ignored while 'is_initialized'
is false.

I have no idea how this ever worked. Nevertheless, this restores the
correct behavior.

Signed-off-by: Yannick Voßen <y.vossen@beckhoff.com>
---
 hw/dma/xlnx-zynq-devcfg.c         | 6 +++++-
 include/hw/dma/xlnx-zynq-devcfg.h | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/dma/xlnx-zynq-devcfg.c b/hw/dma/xlnx-zynq-devcfg.c
index b838c1c0d0..03b5280228 100644
--- a/hw/dma/xlnx-zynq-devcfg.c
+++ b/hw/dma/xlnx-zynq-devcfg.c
@@ -143,9 +143,11 @@ static void xlnx_zynq_devcfg_reset(DeviceState *dev)
     XlnxZynqDevcfg *s = XLNX_ZYNQ_DEVCFG(dev);
     int i;
 
+    s->is_initialized = false;
     for (i = 0; i < XLNX_ZYNQ_DEVCFG_R_MAX; ++i) {
         register_reset(&s->regs_info[i]);
     }
+    s->is_initialized = true;
 }
 
 static void xlnx_zynq_devcfg_dma_go(XlnxZynqDevcfg *s)
@@ -221,7 +223,9 @@ static void r_unlock_post_write(RegisterInfo *reg, uint64_t val)
 {
     XlnxZynqDevcfg *s = XLNX_ZYNQ_DEVCFG(reg->opaque);
     const char *device_prefix = object_get_typename(OBJECT(s));
-
+    if (!s->is_initialized) {
+        return;
+    }
     if (val == R_UNLOCK_MAGIC) {
         DB_PRINT("successful unlock\n");
         s->regs[R_CTRL] |= R_CTRL_PCAP_PR_MASK;
diff --git a/include/hw/dma/xlnx-zynq-devcfg.h b/include/hw/dma/xlnx-zynq-devcfg.h
index e4cf085d70..2ab054e598 100644
--- a/include/hw/dma/xlnx-zynq-devcfg.h
+++ b/include/hw/dma/xlnx-zynq-devcfg.h
@@ -55,6 +55,8 @@ struct XlnxZynqDevcfg {
     XlnxZynqDevcfgDMACmd dma_cmd_fifo[XLNX_ZYNQ_DEVCFG_DMA_CMD_FIFO_LEN];
     uint8_t dma_cmd_fifo_num;
 
+    bool is_initialized;
+
     uint32_t regs[XLNX_ZYNQ_DEVCFG_R_MAX];
     RegisterInfo regs_info[XLNX_ZYNQ_DEVCFG_R_MAX];
 };
-- 
2.49.0