hi Simon, On Tue, 29 Aug 2023 at 22:55, Simon Glass <s...@chromium.org> wrote: > > Hi Sughosh, > > On Mon, 28 Aug 2023 at 12:35, Sughosh Ganu <sughosh.g...@linaro.org> wrote: > > > > hi Simon, > > > > On Mon, 28 Aug 2023 at 23:25, Simon Glass <s...@chromium.org> wrote: > > > > > > Hi Sughosh, > > > > > > On Sat, 26 Aug 2023 at 03:07, Sughosh Ganu <sughosh.g...@linaro.org> > > > wrote: > > > > > > > > Add a document explaining the need for removal of non-compliant > > > > devicetree nodes and properties. Also describe in brief, the macros > > > > that can be used for this removal. > > > > > > > > Signed-off-by: Sughosh Ganu <sughosh.g...@linaro.org> > > > > --- > > > > .../devicetree/dt_non_compliant_purge.rst | 64 +++++++++++++++++++ > > > > 1 file changed, 64 insertions(+) > > > > create mode 100644 doc/develop/devicetree/dt_non_compliant_purge.rst > > > > > > > > diff --git a/doc/develop/devicetree/dt_non_compliant_purge.rst > > > > b/doc/develop/devicetree/dt_non_compliant_purge.rst > > > > new file mode 100644 > > > > index 0000000000..c3a8feab5b > > > > --- /dev/null > > > > +++ b/doc/develop/devicetree/dt_non_compliant_purge.rst > > > > @@ -0,0 +1,64 @@ > > > > +.. SPDX-License-Identifier: GPL-2.0+ > > > > + > > > > +Removal of non-compliant nodes and properties > > > > +============================================= > > > > + > > > > +The devicetree used in U-Boot might contain nodes and properties which > > > > +are specific only to U-Boot, and are not necessarily being used to > > > > +describe hardware but to pass information to U-Boot. An example of > > > > +such a property would be the public key being passed to U-Boot for > > > > +verification. > > > > > > It has nothing to do with describing hardware. The DT can describe > > > other things too. See the /options node, for example. > > > > > > Please don't bring this highly misleading language into U-Boot. > > > > Please point out what is misleading in the above paragraph. What is > > being emphasised in the above paragraph is that certain nodes and > > properties in the devicetree are relevant only in u-boot, and not the > > kernel. And this is precisely what the devicetree maintainers are > > saying [1]. > > That is not relevant though...we need to make sure all the nodes are > in the dt schema. > > It is misleading because you imply that DT should only describe > hardware. That is not true. > > > > > > > > > > + > > > > +This devicetree can then be passed to the OS. Since certain nodes and > > > > +properties are not really describing hardware, and more importantly, > > > > +these are only relevant to U-Boot, bindings for these cannot be > > > > +upstreamed into the devicetree repository. There have been instances > > > > +of attempts being made to upstream such bindings, and these deemed not > > > > +fit for upstreaming. > > > > > > Then either they should not be in U-Boot, or there is a problem with > > > the process. > > > > > > > Not having a binding for these nodes and > > > > +properties means that the devicetree fails the schema compliance tests > > > > +[1]. This also means that the platform cannot get certifications like > > > > +SystemReady [2] which, among other things require a devicetree which > > > > +passes the schema compliance tests. > > > > + > > > > +For such nodes and properties, it has been suggested by the devicetree > > > > +maintainers that the right thing to do is to remove them from the > > > > +devicetree before it gets passed on to the OS [3]. > > > > > > Hard NAK. If we go this way, then no one will ever have an incentive > > > to do the right thing. > > > > > > Please send bindings for Linaro's work, instead. If something is > > > entirely U-Boot-specific, then it can go in /options/u-boot but it > > > still must be in the dt-schema. > > > > Please re-read the document including the last link [1]. If you go > > through that entire thread, you will notice that this is precisely > > what Linaro was trying to do here -- upstream the binding for the > > fwu-mdata node. It is only based on the feedback of the devicetree > > maintainers that this patchset was required. > > It looks like it should go in /options/u-boot ? Can you resubmit it there?
Okay. I will try this approach. If I face any hurdles, or the devicetree maintainers have a different take on this, I will let you know. -sughosh > > The stripping is a no-go for me, sorry. It is absolutely going to > destroy any chance of tidying up DT in U-Boot. > > Please also figure out how to add DT validation to U-Boot, so we can > see what the gap is. Once we have that in, I will be happier to do > workarounds. > > Regards, > Simon > > > > > -sughosh > > > > [1] - > > https://lore.kernel.org/u-boot/cal_jsqjn4fehoml7z3yj0wj9bpx1ose7zf26l_gv2os6cg-...@mail.gmail.com/#t > > > > > > > > > + > > > > +Removing nodes/properties > > > > +------------------------- > > > > + > > > > +In U-Boot, this is been done through adding information on such nodes > > > > +and properties in a list. The entire node can be deleted, or a > > > > +specific property under a node can be deleted. The list of such nodes > > > > +and properties is generated at compile time, and the function to purge > > > > +these can be invoked through a EVT_FT_FIXUP event notify call. > > > > + > > > > +For deleting a node, this can be done by declaring a macro:: > > > > + > > > > + DT_NON_COMPLIANT_PURGE(fwu_mdata) = { > > > > + .node_path = "/fwu-mdata", > > > > + }; > > > > + > > > > +Similarly, for deleting a property under a node, that can be done by > > > > +specifying the property name:: > > > > + > > > > + DT_NON_COMPLIANT_PURGE(capsule_key) = { > > > > + .node_path = "/signature", > > > > + .prop = "capsule-key", > > > > + }; > > > > + > > > > +In the first example, the entire node with path /fwu-mdata will be > > > > +removed. In the second example, the property capsule-key > > > > +under /signature node will be removed. > > > > + > > > > +Similarly, a list of nodes and properties can be specified using the > > > > +following macro:: > > > > + > > > > + DT_NON_COMPLIANT_PURGE_LIST(foo) = { > > > > + { .node_path = "/some_node", .prop = "some_bar" }, > > > > + { .node_path = "/some_node" }, > > > > + }; > > > > + > > > > +[1] - https://github.com/devicetree-org/dt-schema > > > > +[2] - > > > > https://www.arm.com/architecture/system-architectures/systemready-certification-program > > > > +[3] - > > > > https://lore.kernel.org/u-boot/cal_jsqjn4fehoml7z3yj0wj9bpx1ose7zf26l_gv2os6cg-...@mail.gmail.com/ > > > > -- > > > > 2.34.1 > > > > > > > > > > Regards, > > > Simon
