On Tue, 2017-01-10 at 18:34 +0000, Mark Rutland wrote:
Looking at the git log for arch/arm64/boot/dts/arm, most updates are simply adding new descriptions, so a DTB from a year ago should work just fine with mainline (modulo the Juno PCI window issue, which was a DTB bug). Upgrading kernel shouldn't require a DTB upgrade to see equivalent functionality.
But if you want the new functionality in the kernel, why should you be forced to wait for the bootloader to catch up (or do that work yourself) then upgrade to that new bootloader version? And what about the poor devs working on that new functionality, they're going to need to use not upstream device-trees. Then there's all the firmware and system configuration stuff that's in device-tree.
Basically, in the real world, devive-tree is a system configuration file you need to hack to get all the pieces you're lumbered with to work together and if you don't have control of it's contents you're stuffed.
(Well, we're stuffed anyway with the umpteen layers of OSes/firmware/hypervisors all struggling for control of every computer system.)