Where can I find the hardware related release notes for SSP releases?
The release notes associated with SSP releases are all software related. Hardware related updates are posted here in the Synergy Knowledge Base and/or in the Renesas Rulz Synergy forum. Just search on the term you are most interested in and you will find the related posts.
Synergy Knowledge Base: https://knowledgebase.renesas.com/Renesas_Synergy_Platform/Renesas_Synergy_Knowledge_Base
Renesas Rulz Synergy Forum: http://renesasrulz.com/synergy/f/206.aspx