From your kernel source link
> DVR type users will probably ship with this enabled for movie content management.
Indeed where the DRM error message comes from https://github.com/torvalds/linux/blob/ffd294d346d185b70e28b...
> CPRM may make this media unusable
CPRM?
> Content Protection for Recordable Media and Pre-Recorded Media (CPRM / CPPM) is a mechanism for restricting the copying, moving, and deletion of digital media on a host device, such as a personal computer, or other player. It is a form of digital rights management (DRM) developed by The 4C Entity, LLC (consisting of IBM, Intel, Matsushita and Toshiba).
How can we be sure which CPRM it is though? Ah the kernel maintainers actually had an argument about it at the time https://www.linuxjournal.com/article/5091 https://www.linuxjournal.com/article/5092