On Thu, 14 Dec 2023 at 23:53, Tom Rini <tr...@konsulko.com> wrote: > > On Thu, Dec 14, 2023 at 03:53:11PM +0100, neil.armstr...@linaro.org wrote: > > Hi, > > > > On 14/12/2023 14:50, Sumit Garg wrote: > > > Prerquisite > > > > s/Prerquisite/Prerequisite/ > >
Ack. > > > ----------- > > > > > > This patch series requires devicetree-rebasing git repo to be added as a > > > subtree to the main U-boot repo via: > > > > > > $ git subtree add --prefix devicetree-rebasing \ > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git > > > \ > > > v6.6-dts --squash > > > > So I think the big question is: when should the subtree be updated ? > > > > Because as we discussed in the previous GH pull request, if a bindings > > changes > > was made in the upstream Linux DT, then the subtree update should wait until > > the u-boot support is merged before updating. This could cause a lot of > > frustration. > > > > And this could cause a lot of regressions, even more if both Linux and > > U-boot are > > not maintained by the same people. > > I think some of the important questions to ask are, how often / likely > are the breakages to occur? It seems like these days it's either: > - U-Boot had an early version of the binding and we already state we > don't support backwards compatibility here. It should be on the > maintainer to be proactive in this case. > - It's a "the DT was wrong about the hardware, sorry not sorry it's an > incompatible DTS change now". This too is hopefully the kind of thing > that at least board maintainers will be more actively aware of needing > to deal with in U-Boot, if it's really a problem. Agree, also per discussion with Linux DT maintainers, they do care for DT backwards and forward compatibility. I expect the ABI changes to be rare. In case there is an ABI change then it will be great if Linux DT maintainers can ask contributors to CC corresponding U-boot platform maintainers too. BTW, Rob is already working on a tool to detect ABI changes as he described here [1]. If U-boot platform maintainers have any ideas regarding what would constitute an ABI change then feel free to share those. [1] https://lore.kernel.org/all/cal_jsqlo4nxrj93ddsfp3uyls08v02amnbccnsdj0mbbomc...@mail.gmail.com/ > > So I would plan on grabbing only full kernel releases and in to -next as > soon as possible. Our cadences don't match up exactly, but I think do > fairly well enough. I suppose that would give ample time to the U-boot platform/board maintainer to fix any ABI change regression found in the -next branch. That being said we aren't completely immune to changes to devicetree-rebasing subtree. If there is an DT ABI change that will take significant effort to fix in U-boot then we are open to accepting a revert given that it will be fixed before next uprev. -Sumit > > -- > Tom
