This is a futile discussion. It would not make any difference if AMD released the PSP source code. The problem with the PSP is not it's firmware, it is a much deeper fundamental architectural problem as outlined in (unfortunately dead link) https://www.reddit.com/r/linux/comments/5x5xl3/amd_to_consid...
If AMD would release the source code, the PSP would still remain a black box controlled by the manufacturer. It is an autonomous universal computer (with it's own CPU, RAM, ROM, clock...) which can load/run anytime any software AMD wants it to. There is no way for the user to tell what software it is running at the moment and what it is doing on the platform. It has fully privileged access to the users resources while it offers no interface for the user (only a very minimal low level interface).
So the fundamental problem is, that it takes the control of the platform away from the user, the manufacturer is ultimately in control on the platform. This is what goes against the philosophy of Coreboot/Libreboot (of being completely in control of the platform), not simply the encrypted PSP firmware blob.
Knowing that blob would not compromise the PSP and would not give the control back to the user.
If AMD would release the source code, the PSP would still remain a black box controlled by the manufacturer. It is an autonomous universal computer (with it's own CPU, RAM, ROM, clock...) which can load/run anytime any software AMD wants it to. There is no way for the user to tell what software it is running at the moment and what it is doing on the platform. It has fully privileged access to the users resources while it offers no interface for the user (only a very minimal low level interface).
So the fundamental problem is, that it takes the control of the platform away from the user, the manufacturer is ultimately in control on the platform. This is what goes against the philosophy of Coreboot/Libreboot (of being completely in control of the platform), not simply the encrypted PSP firmware blob.
Knowing that blob would not compromise the PSP and would not give the control back to the user.