Example 30 DMA memcpy does not work on Jetson Xavier Agx

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my env is

Linux ubuntu 5.10.104-tegra #1 SMP PREEMPT Tue Jan 24 15:09:44 PST 2023 aarch64 aarch64 aarch64 GNU/Linux

and the dmesg is as below:

Aug 16 07:56:35 ubuntu kernel: my_dma_memcpy - Init
Aug 16 07:56:35 ubuntu kernel: my_dma_memcpy - Before DMA Transfer: src_buf[0] = 12
Aug 16 07:56:35 ubuntu kernel: my_dma_memcpy - Before DMA Transfer: dst_buf[0] = 0
Aug 16 07:56:38 ubuntu kernel: my_dma_memcpy - Timeout!
Aug 16 07:56:38 ubuntu kernel: my_dma_memcpy - Error on DMA transfer