[PATCH 3/4] arm: dts: k3-*-binman.dtsi: Clean up and templatize boot binaries
Matthias Schiffer
matthias.schiffer at ew.tq-group.com
Thu Apr 4 10:04:41 CEST 2024
On Wed, 2024-04-03 at 17:51 +0200, Michael Walle wrote:
> Hi,
>
> > > > > > And on top of that, it will just be a base board and there will
> > > > > > likely be some carrier device trees (overlay? I'm not sure yet).
> > > > > >
> > > > > > As far as I can tell, you've put the memory configuration into the
> > > > > > device tree, so I'll probably need to switch between them somehow.
> > > > >
> > > > > The "k3-<soc>-ddr.dtsi" file will be present in your k3-<board>r5.dts
> > > > > which makes sense, the memory configuration depends on the board.
> > > >
> > >
> > > k3-<board>-ddr.dtsi* (e.g J721E EVM vs. SK boards consume different memory
> > > configurations.
>
> Right.
>
> > > > And one board might have multiple configuration depending on the
> > > > variant of the board. Typically, one board is available with
> > > > different memory options. i.e. 1GiB, 4GiB and so on. The actual RAM
> > > > chips can come from different manufacturers. So all all, I presume
> > > > there will be different RAM settings, i.e. different
> > > > k3-<soc>-ddr.dtsi. But I have to switch between the setting during
> > > > runtime because there will be only one boot image for that board.
> > >
> > > This is a runtime dynamic DDR configuration support you are describing
> > > correct? This means you would be including all the supported memory option
> > > DTSIs in your k3-<board>-r5.dts correct and probably do some board magic
> > > code in the SPL DDR driver to choose the DTB. How is this affecting the
> > > packing of the final bootloader which will anyways pack the whole R5 DTB?
>
> Correct, the DDR configuration should be chosen at runtime after
> reading some board strappings. Unless, it will work with with the
> same configuration which seems unlikely to me. But it is not an
> unusual configuration I'd say.
>
> I haven't looked into this in detail, but to me it seems not that
> obvious how to do that in a generic/upstreamable way. Multiple
> device nodes sounds wrong. Thus, I'd likely need different device
> trees for the different memory configurations for the R5 SPL. Not
> sure that is yet possible with u-boot, though. If you have any
> better idea, I'm all ears.
>
> > > > > > Also, regarding the board variants, I'll probably need to choose
> > > > > > between multiple device trees. That is invisible to the user,
> > > > > > because u-boot will choose the correct DTB according a board
> > > > > > strapping, which btw. works really fine, see for example
> > > > > > (boards/kontron/sl28/spl.c:board_fit_config_name_match).
> > > > >
> > > > > Again, this is assuming that there is some HW blown register available
> > > > > for the board to use (or in our earlier K3 case, the EEPROM) but that is
> > > > > not necessarily true every time.
> > > >
> > > > No, that is of course board dependent. It is just an example that
> > > > there are boards with more than one DTB.
> > > >
> > > > Let's step back a bit. Right now, there is
> > > > k3-<soc>-<board>-binman.dtsi
> > > > which is fine. But it seems, that TI is heading towards a common
> > > > k3-<soc>-binman.dtsi
> > > > which is intended to be used by all the boards that are using that
> > > > particular SoC, correct me if I'm wrong here. Now the problem with
> > > > that is that you hardcode the FIT configuations which are really
> > > > board dependent and assume that there will be exactly one DTB per
> > > > board, i.e. your "#define SPL_BOARD_DTB" etc.
> > > >
> > >
> > > Correct, but as I mentioned in the earlier message, if your board supports
> > > more than 1 FIT configuration, you can easily extend the image and add more
> > > configurations.
> > >
> > > > Thus, what I was trying to say is that you should split all the
> > > > board independent configuration (dt fragments) from the board
> > > > specific configuration.
> > > >
> > > > And again, of course I could just ignore the k3-<soc>-binman.dtsi
> > > > and just use a suitable copy "k3-<soc>-<myboard>-binman.dtsi" for my
> > > > board. But as I said, I'm not sure, this is the way to go and I have
> > > > a slight feeling I will be asked to reuse the "k3-<soc>-binman.dtsi"
> > > > when I submit my board support.
> > > >
> > > > > >
> > > > > > I don't think it makes much sense to hardcode your generic
> > > > > > *-binman.dtsi to just one FIT configuration. I'd rather see a split
> > > > > > between generic things which are shared across all boards and board
> > > > > > specifics, like the FIT configuration. I mean I could just copy all
> > > > >
> > > > > Correct me if I'm wrong, but my understanding is that you would want to
> > > > > add more FDT blobs in the *-binman.dtsi correct? That is still possible,
> > > > > adding another "fdt-1" and "conf-1" in the
> > > > >
> > > > > Something like this in your <board>-u-boot.dtsi,
> > > > >
> > > > > tispl {
> > > > > insert-template = <&ti_spl>;
> > > > > fit {
> > > > > images {
> > > > > fdt-1 {
> > > > > ...
> > > > > };
> > > > > };
> > > > > configurations {
> > > > > conf-1 {
> > > > > ...
> > > > > };
> > > > > };
> > > > > };
> > > > > };
> > > >
> > > > Then you have the information at two places. One being the "#define
> > > > SPL_BOARD_DTB" stuff and the other one being in this additional DT
> > > > fragment. That is really confusing.
> > > >
> > >
> > > Hm... maybe. I personally don't see it as confusing. Even when picking
> > > between multiple DTBs, you will have a default DTB in any case, marking that
> > > as a macro wouldn't be confusing right? We'll need to get a third opinion on
> > > here then, I had seen your ping on IRC [1], putting it here for the others
> > > as well.
> > >
> >
> > As I see it, it's not like we are making the fdt-0 non overridable, you
> > can still override it in your configs to make it cleaner if you want for
> > your board template, I don't think that -
>
> Though it is not overriding but rather merging, correct? So one
> would need to first erase the node just to create it again. Which
> looks more like a workaround.
>
> > tispl {
> > insert-template = <&ti_spl>;
> > fit {
> > images {
> > fdt-0 {
> > ...
> > };
> > fdt-1 {
> > ...
> > };
> > };
> > configurations {
> > conf-0 {
> > ...
> > };
> > conf-1 {
> > ...
> > };
> > };
> > };
> > };
>
> >
> > is not doable. It might be a bit duplicate but if I think about it but
> > we are not losing out on extending the templates for multiple DTBs even
> > with this design. I know it might not be what you want but I feel that
> > for single DTB it's really convenient with the macro stuff and we don't
> > have to override any of the other binman nodes.
>
> I've raised my concern about stuffing board dependent stuff into the
> now generic "k3-<soc>-binman.dtsi". I get it that it will work for
> 90% of the boards and that it is very convenient. I'd have rather
> seen a split of lets say
> k3-<soc>-binman.dtsi
> and
> k3-one-dtb-template-binman.dtsi
>
> All the generic stuff goes into k3-soc-binman.dtsi whereas 90% of
> the boards might still use the second dtsi with some define magic.
> But it seems you've already made your mind up on that :)
>
> -michael
>
My hope would be that we can get rid of board-specific binman configuration in the common case
altogether for the K3 SoC families, using @fdt-SEQ etc. generator sections that will just include
all FDTs configured in Kconfig.
A while ago [1], this was blocked on ti-secure signing not working with generator sections, and
according to my experiments, this is still the case in U-Boot 2024.01 (and looking at the Git log,
also 2024.04/master/next). Are there still plans to make this work? Are there any other blockers?
Best regards,
Matthias
[1] https://lists.denx.de/pipermail/u-boot/2023-July/525095.html
>
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