On Mon, 22 Jan 2024 11:49:59 -0500 Tom Rini trini@konsulko.com wrote:
Hi Tom,
On Mon, Jan 22, 2024 at 11:45:15AM +0000, Andre Przywara wrote:
On Wed, 10 Jan 2024 16:05:36 +0530 Sumit Garg sumit.garg@linaro.org wrote:
Hi,
I certainly welcome this more automatic synchronisation of the DTs, however have one comment about the upcoming sync process:
... However, Linux kernel DT maintainers proposed [2] for U-Boot to rather use devicetree-rebasing repo [3] which is a forked copy from Linux kernel for DT source files as well as bindings. It is tagged at every Linux kernel major release or intermideate release candidates. So here I have tried to reuse that to bring DT bingings compliance as well as a standard way to maintain a regular sync of DT source files with Linux kernel.
In order to maintain devicetree files sync, U-Boot will maintains a Git subtree for devicetee-rebasing repo as `dts/upstream` sub-directory. U-Boot will regularly sync `dts/upstream/` subtree whenever the next window opens with the next available kernel major release.
I hope this doesn't need to stay that restricted? Can we either sync more often, or at least on the kernel's -rc1, and not only on a "full" release?
The reason I ask is that we have a chicken-egg problem here: without a DT merged into the kernel tree, no U-Boot board support can be merged. And without U-Boot support, we cannot boot a kernel, at least not in the canonical way.
Since the U-Boot and kernel merge windows are not in phase, for sunxi I try to sync the kernel DTs either as early as possible (-rc1, sometimes even before, when the maintainers have merged them into their tree), or sometimes "out of season", if a board defconfig patch is coming up.
Otherwise new board support, which typically has a very low regression risk for the rest of the code base, would need to be delayed until the next release. In the worst case the U-Boot merge windows opens one week before a kernel release, then new boards need to wait three months?
Would it be to bad to bring in board X with OF_UPSTREAM=n for one U-Boot release, and then with the next one switch to OF_UPSTREAM=y (and delete the dts from arch/) for the next release, when we would have gotten back in sync?
Ah, I didn't look into the actual patches, but if this provision is there, that sounds surely acceptable. It might still be good to sync earlier than the .0 kernel release: if it appears in Linus' tree, it had already seen a good share of review and testing. And with the U-Boot releases being always further away than the next kernel release, we could pull fixes still in time. So we could pick the latest -rc (or .0 release, whichever is more recent) when the U-Boot merge window opens?
Cheers, Andre