However, the linaro kernel includes the PVR driver for GB indeed
(DDK1.7) but for Ubuntu we use an external PVR module that is provided
as an out-of-driver. so you might be able to update the in-tree PVR to
1.8 without impacting Ubuntu images at all.

This was what I was proposing as a general rule:
1. in-kernel module == android
2. out-of-kernel tree == ubuntu would definitely recommend that we main a common base kernel used for

Ubuntu and put the Android stuff in another branch as I am not sure if
the android bits will impact Ubuntu GFX... it might be able to be
managed with flags eventually, but let's start with a branch.

I would prefer if we default to use the same branch and only start branching off
after good evaluation and knowing that there are issues (rather than suspecting).