Device Enryption Support is not available due to an error: Reasons for failed automatic device encryption un-allowed dma ...

The error "Reasons for failed automatic device encryption un-allowed DMA capable bus/device(s) detected" comes in system information under "Device Encryption Support". Because of this I cannot turn on device encryption. Please let me know how to solve this issue.

I haven't reinstalled the operating system. However, I have added another stick of RAM.