About cargo workspace root for the rust code

[hanzooo]

For the entire project, I found that rust_analyzer can't provide language services for the rust source code, because Cargo.toml is not configured in the root directory (it is ok to open the rust project in the corresponding subdirectory, for example, a workspace is configured in cayley package, and another package for redis).
If we want to read and analyze the rust code more conveniently in the whole project, maybe we need a Cargo.toml in the root directory and configure the workspace to include all packages?
Or are there any considerations for the current configuration?