09.12.2019 23:47, Mark Brown пишет:
On Mon, Dec 09, 2019 at 11:31:59PM +0300, Dmitry Osipenko wrote:
09.12.2019 19:40, Mark Brown пишет:
Why would this need to be a stable fix? Presumably people with stable kernels are using the old device tree anyway?
At least Rob Herring is asking to maintain backwards compatibility because some ditros are using newer device-trees with stable kernels.
You're talking about forwards compatibility not backwards here. Are those distros actually using LTS kernels?
I think openSUSE Leap could be one of those distros that use LTS kernel with newer device-trees, but that's not 100%. Maybe Rob could help clarifying that.
I'm personally also tending to use the newer DTB with older kernel version whenever there is a need to check something using stable kernel. Perhaps losing sound is not very important, but will be nicer if that doesn't happen.
That really does sound like a "you broke it, you get all the pieces" situation TBH... I'd be a lot more comfortable if the stable kernels were sticking to bugfix only though I do appreciate that they're not really that any more.
In some cases it could be painful to maintain device-tree compatibility for platforms like NVIDIA Tegra SoCs because hardware wasn't modeled correctly from the start.
I agree that people should use relevant device-trees. It's quite a lot of hassle to care about compatibility for platforms that are permanently in a development state. It could be more reasonable to go through the pain if kernel required a full-featured device tree for every SoC from the start.
But maybe Tegra / device-tree maintainers have a different opinion. IIUC, device-trees are meant to be stable and software-agnostic, at least that was the case not so long time ago and I don't think that this premise changed.