From: Sascha Hauer <sha@pengutronix.de>
To: Trent Piepho <trent.piepho@igorinstitute.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH v2 1/1] kbuild: dtc: Allow adding device tree fragments via config
Date: Fri, 1 Oct 2021 14:52:13 +0200 [thread overview]
Message-ID: <20211001125213.GT24834@pengutronix.de> (raw)
In-Reply-To: <20210922181336.1350460-1-trent.piepho@igorinstitute.com>
Hi Trent,
On Wed, Sep 22, 2021 at 11:13:36AM -0700, Trent Piepho wrote:
> This introduces a config variable that allows adding additional fragments
> to the Barebox device tree(s).
>
> Example uses are adjusting the flash partition layout, adding barebox
> state variables, or adding an I2C device. These can be now be done with
> build configuration only, without needing to patch the existing dts
> files in the Barebox source.
>
> The advantage is greater when an external build system, such as Yocto or
> Buildroot, is being used to build Barebox. The build system can drop in
> a dts fragment to partition flash and build from unaltered Barebox
> source. This avoids the need for cumbersome maintenance of patch files
> to modify Barebox's source for each flash partition layout.
>
> Preprocessing the dts file gains another layer, where a generated dts
> source consisting of an include directive for the original dts source is
> followed by more includes for each fragment. This is piped to the
> existing preprocessor call on stdin to avoid another temporary file.
> cpp/dtc will correctly identify errors in the source files they occur
> in. The -MT option is used so the cpp auto-dependencies reference the
> original dts source and not the generated code passed on stdin.
>
> A preprocessor macro named after the base dts file, e.g. foo-bar.dts
> will define foo_bar_dts, will be defined so that the fragments can
> possibly operate differently based on which image's dts is being built.
>
> Signed-off-by: Trent Piepho <trent.piepho@igorinstitute.com>
> ---
> Changes from v1:
> - Remove 2nd config variable for in-tree fragments.
> - Add macro to preproccessed dts
I tested this myself and it works as expected. Applied with a little
change
> +config EXTERNAL_DTS_FRAGMENTS
> + string "external dts file fragments"
> + depends on OFTREE
> + help
> + List of dts fragment files that will be appended to Barebox's device
> + tree(s) source when building the dtb file(s). If multiple files are
> + listed, they will be appended in order. Relative filenames will use
> + the dtc include search path.
> +
> + A preprocessor macro based on the name of the main dts will be
> + defined, which allows the dts fragments to based on which image of a
> + multi image build they are being used in.
Changed this to:
A preprocessor macro based on the name of the main dts will be
defined, which allows the dts fragments to based on which image of a
multi image build they are being used in. Given the dts filename
used for a board is "foo-board.dts" the external dts usage can be
limited to that board with
#ifdef foo_board_dts
...
#endif
To make that point a little more clear.
Sascha
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
next prev parent reply other threads:[~2021-10-01 12:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 18:13 Trent Piepho
2021-10-01 12:52 ` Sascha Hauer [this message]
2022-01-26 12:29 ` Antony Pavlov
2022-01-26 22:10 ` Trent Piepho
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211001125213.GT24834@pengutronix.de \
--to=sha@pengutronix.de \
--cc=barebox@lists.infradead.org \
--cc=trent.piepho@igorinstitute.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox