On Mon, 7 Oct 2024 at 12:25, Chao Liu <chao....@yeah.net> wrote:
>
> During the initialization phase, we've encountered an issue where the
> UNLOCK register is inadvertently cleared. This results in devcfg MR being
> disabled, which in turn leads to unexpected memory access exceptions when
> attempting subsequent accesses to the devcfg register. This behavior is not
> consistent with the hardware specifications.
>
> This bug was not found earlier because the ignore_memory_transaction_failures
> flag was enabled, which ignored exceptions from devcfg devices
> when access was disabled.
>
> Signed-off-by: Chao Liu <chao....@yeah.net>
> ---
> hw/dma/xlnx-zynq-devcfg.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/hw/dma/xlnx-zynq-devcfg.c b/hw/dma/xlnx-zynq-devcfg.c
> index e5eff9abc0..af8cc72471 100644
> --- a/hw/dma/xlnx-zynq-devcfg.c
> +++ b/hw/dma/xlnx-zynq-devcfg.c
> @@ -144,7 +144,12 @@ static void xlnx_zynq_devcfg_reset(DeviceState *dev)
> int i;
>
> for (i = 0; i < XLNX_ZYNQ_DEVCFG_R_MAX; ++i) {
> - register_reset(&s->regs_info[i]);
> + if (s->regs_info[i].access) {
> + if (s->regs_info[i].access->addr == A_UNLOCK) {
> + continue;
> + }
> + register_reset(&s->regs_info[i]);
> + }
> }
This looks strange. Reset should reset things. If the
UNLOCK register's reset behaviour is wrong, then shouldn't
we fix it, rather than explicitly skipping resetting it ?
thanks
-- PMM
