Re: [PATCH 1/1 RFC] treewide: Deprecate OF_PRIOR_STAGE

Simon Glass
2021-10-13T18:06:14Z

Hi Thomas,

On Wed, 13 Oct 2021 at 11:36, Thomas Fitzsimmons <fitzsim@fitzsim.org> wrote:
>
> Simon Glass <sjg@chromium.org> writes:
>
> [...]
>
> > On Wed, 13 Oct 2021 at 10:26, Thomas Fitzsimmons <fitzsim@fitzsim.org> wrote:
> >>
> >> Simon Glass <sjg@chromium.org> writes:
> >>
> >> [...]
> >>
> >> >> > I think one option is better than two. I have a slight preference for
> >> >> > OF_PRIOR_STAGE because it is board-agnostic, but I'm not sure it
> >> >> > matters, since some of these boards are doing strange things anyway
> >> >> > and cannot use OF_PRIOR_STAGE. So let's go with this.
> >> >>
> >> >> For now it's easier getting rid of OF_PRIOR_STAGE than OF_BOARD.
> >> >> Once we unify OF_PRIOR_STAGE/OF_BOARD and OF_HOSTFILE, then
> >> >> I can send a patch on top of that, which removes the board_fdt_blob_setup()
> >> >> and just stores the address in a similar fashion to the removed
> >> >> 'prior_stage_fdt_address'. That way we can get rid of architecture
> >> >> specific constructs wrt to DT in gd. The callback is a bit more of a pain to
> >> >> maintain for multiple boards but is more flexible than an address in a
> >> >> register. In any case we can do something along the lines of:
> >> >>
> >> >> Check register (or blob list or whatever)
> >> >> if (valid dtb)
> >> >> fixup/amend/use (depending on what we decide)
> >> >> else
> >> >> arch specific callback
> >> >>
> >> >> That should give us enough flexibility to deal with future boards (famous
> >> >> last words).
> >> >
> >> > SGTM
> >>
> >> This sounds like a good generalization that would still work for the
> >> bcm7445 and bcm7260 boards. I'll test this approach on the evaluation
> >> boards I have.
> >>
> >> For the BCM7445 I may be able to import the evaluation board device tree
> >> that Broadcom publishes as part of stblinux. At runtime I may need to
> >> merge some of the in-memory items generated by BOLT, but I'll try to
> >> make this work.
> >
> > That would be good.
> >
> >> The BCM7260 DTS is not publicly available though, as far as I know.
> >
> > Presumably it can be dumped from U-Boot?
>
> Technically, yes, but I wouldn't want to publish the result for various
> reasons; e.g., it would be specific to the evaluation boards I have, and
> it may contain vendor-specific fields. I'd much rather this one remain
> a stub, until/unless Broadcom publishes a generic BCM7260 DTS under a
> free license.

OK. Do you think you could submit a patch to do all this, including
some docs about the current situation?

Regards,
Simon

> Thomas