Mainline linux is often used in the embedded Linux community to describe a kernel downloaded from the official repository rather than an old, patched-to-death o

Mainline linux is often used in the embedded Linux community to describe a kernel downloaded from the official repository rather than an old, patched-to-death one provided by the SoC vendor. Having prepared embedded devices myself, it is quite common to patch the kernel you are working with to work around quirks in your hardware. However, it is much more pleasant to do so on a mainline kernel than on something that was already patched and never maintained. Also note that the author mentions that he is currently in the process of getting his patches merged in Linux, and that most of the work should be included in 5.9. So perhaps not mainline yet, but future mainline definitely.