Not able to access rpmsg device /sys/bus/rpmsg/devices/virtio0.rpmsg-openamp-demo-channel.-1.0

[SrMujjiga]

Xilinx Zynq UltraScale+ MpSoc ZCU102,
Xilinx Linux Kernel 4.19 with debian rfs on A53
Included through BSP:
FreeRTOS v10
OpenAMP: v1.5
Libmetal: v2.0

Zynq remoteproc driver is statically built into the linux kernel. Once the board comes up, Applications on the master ( A53 ) can run echo stop and echo start to bring up the RPU Core. In some cases it is observed that echo stop/echo start does not help to bring up the RPU core. Not able to access rpmsg device /sys/bus/rpmsg/devices/virtio0.rpmsg-openamp-demo-channel.-1.0 message is seen . Rebooting the board seems to be the only way to address this problem which we would like to avoid. As a first step, made zynq remote proc driver as loadable kernel module and insmod/rmmod the driver prior to echo start/echo stop. But this also seems to be not helping once access failure for virtio0.rpmsg-openamp-demo-channel.-1.0 is seen.

Can some one help with below questions.
Why is the access failure reported ?
How to recover from this state without rebooting the board ?

Thanks.