If I add a list of ciphers, I would add all that are supported but a note could mention other things. Are there any boards that support a different cipher? I don't want to make a change just for the helios.
I don't think you need to bother listing all the supported ciphers because the list would be super long since many possible combination. It's better to limit the choice to the best 2 ciphers which are recommended by most linux distrib, including cryptsetup itself :
I did a bit of research and most ARM SoC have crypto engine
The basic features of their encryption and decryption engine are :
AES 128/192/256 key mode
ECB/CBC chain mode
SHA-1, SHA-256, and MD5 hash func
Actually I found that some last gen ARM SoC familly even support XTS chain mode. But overall I think most ARM SoC would get better performance by using aes-cbc-essiv:sha256 instead of aes-xts-plain64.
I would recommend however to leave aes-xts-plain64 as the default and let user choose explicitly the other cipher if needed. Up to the board developer to advertise such improvement tweaks