Qsys: During system generation, disconnected interfaces cause warnings even if the interfaces are optional

Description

If a Qsys system that contains IP cores such as ALTPLL or a UniPHY component has any disconnected interfaces at generation time, Qsys issues errors similar to the following, even if the interfaces are optional:

Warning: top_system.sdram: sdram.status must be exported, or connected to a matching conduit. Warning: top_system.sdram: sdram.local_powerdown must be exported, or connected to a matching conduit.

Resolution

Check with the component or IP author to verify whether the interfaces listed in the errors are not required. You can safely ignore these warnings if the interfaces are optional. If they are not optional, connect the interfaces.