Absolutely right.
Not all of HP's printers are free software compatible. The driver is although
you would have to take a look at the documentation. HP is one of the only
companies that does a good job of documenting all its printers for GNU/Linux.
The one itch I have with them in regards to printers is they don't advertise
GNU/Linux on the box or if a printer is freedom friendly. The online
documentation doesn't use quite the right wording although despite it you can
determine from it which printers are free software compatible.
The key things you want to check for are:
Support level: Full
HP Recommended? Yes
Driver plug-in: None
Requires firmware download: No
If all these things are true in the documentation your HP printer should (or
at least eventually) work with Trisquel.
There are other devices out there that have non-free firmware as well
although the drivers are free. All USB N wifi cards for instance with the
exception of the ones using the AR9170 chipset are dependent on non-free
firmware. I'm not 100% sure if every N USB chipset has free drivers although
many/most do. The other thing we always verify with wireless chipsets is
mainline kernel support. If that exists and it's got no firmware or free
firmware all derivative kernels (like libre-kernel and debian's kernel)
should have support. There are almost no exceptions. The one or two
exceptions are where there is a bug (free firmware hasn't been packaged for
the distribution) or specialised distribution for a device with little
storage space (routers for instance). There may be some other exceptions with
devices utilising more storage space although non-PC. Like cell phones and
other handhelds. There just isn't a point to including firmware/driver when
the device hasn't got the ports or there is already built-in wireless.
