On Thu, Dec 14, 2023 at 01:48:42PM -0600, Rob Herring wrote:
On Thu, Dec 14, 2023 at 12:23 PM Tom Rini trini@konsulko.com wrote:
On Thu, Dec 14, 2023 at 03:53:11PM +0100, neil.armstrong@linaro.org wrote:
Hi,
On 14/12/2023 14:50, Sumit Garg wrote:
Prerquisite
s/Prerquisite/Prerequisite/
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.
A common issue in the kernel is with forward compatibility when platforms add new resources from a new provider. Then the kernel expects a driver for the provider and waits for the dependency. Of course, older kernels don't have that provider driver and so the dependency is never met. Not sure if u-boot will have similar issues? At least you should/could know if the provider driver exists or not. (The kernel doesn't because modules.)
I think we'll be fine, but time will tell. And perhaps the more frequent re-syncing will make any sort of corner cases show up more quickly and be something we can figure out how to resolve going forward really.