On Fri, Jan 14, 2022 at 10:25:03AM +0100, Geert Uytterhoeven wrote:

Hi Rob,

On Fri, Jan 14, 2022 at 3:10 AM Rob Herring [off-list ref] wrote:

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On Thu, Jan 6, 2022 at 11:23 AM Frank Rowand [off-list ref] wrote:

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Patient Geert has pinged again.

If it's not a patch to be reviewed, then I'm not going to see it most
likely. I don't read the DT list regularly...

Fair enough...

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If I remember correctly you guys were not thrilled with this idea, but
also did not seem strongly against it.  Are you willing to go along
with .dtso for overlay source files?  If so, I will revive this patch
series.

David, if you are against supporting .dtso in the dtc compiler then
the kernel can still support it through make rules.

TBH, I barely remember the earlier discussion.  I am more or less
indifferent on .dtso.

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I'm not really interested in diverging from dtc. I'd suggest moving
the discussion to dtc list and/or devicetree-spec if you want to get
more attention on this.

What needs to be supported in the dtc compiler?
The fallback passed to guess_input_format() is "dts".
So this has been working out-of-the-box since forever?

Right.  I usually like to supply -I and -O to dtc explicitly, in which
case the extensions basically irrelevant.

I suppose we could also issue warnings if the /plugin/ tag doesn't
match the file extension.

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Also, keep in mind that extensions also affect MIME types which
someone was also asking about recently.

You mean "MIME type of Devicetree Blobs and Sources"[1]?
According to [2](2022-01-13), none of that has happened.

[1] https://www.spinics.net/lists/devicetree-spec/msg00938.html
[2] https://www.iana.org/assignments/media-types/media-types.xhtml

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On 1/6/22 3:00 AM, Geert Uytterhoeven wrote:

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On Tue, Aug 24, 2021 at 11:20 AM Geert Uytterhoeven
[off-list ref] wrote:

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On Tue, Jun 22, 2021 at 11:44 AM Geert Uytterhoeven
[off-list ref] wrote:

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On Sat, May 29, 2021 at 12:16 PM Geert Uytterhoeven
[off-list ref] wrote:

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On Sat, May 29, 2021 at 7:16 AM David Gibson
[off-list ref] wrote:

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On Thu, May 27, 2021 at 09:21:05AM +0200, Geert Uytterhoeven wrote:
65;6401;1c> On Thu, May 27, 2021 at 3:48 AM David Gibson

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[off-list ref] wrote:

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On Wed, May 26, 2021 at 04:21:48PM -0500, Frank Rowand wrote:

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On 5/26/21 1:11 AM, Viresh Kumar wrote:

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On 22-04-21, 13:54, Frank Rowand wrote:

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On 4/22/21 3:44 AM, Geert Uytterhoeven wrote:

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On Mon, Mar 29, 2021 at 9:23 PM Frank Rowand [off-list ref] wrote:

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On 3/27/21 12:40 PM, Rob Herring wrote:

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On Wed, Mar 24, 2021 at 05:37:13PM -0500, frowand.list@gmail.com wrote:

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From: Frank Rowand <redacted>

Add Makefile rule to build .dtbo.o assembly file from overlay .dtso
source file.

Rename unittest .dts overlay source files to use .dtso suffix.

I'm pretty lukewarm on .dtso...

I was originally also, but I'm warming up to it.

What's the status of this?

I was planning to resend on top of the upcoming -rc1.

Ping.

Thanks for the prod...

The .dtso convention was added to the dtc compiler, then a patch was
accepted to revert one mention of .dtso ,though there still remains
two location where .dtbo is still recognized (guess_type_by_name() in
dtc and the help text of the fdtoverlay program).

It seems that the general .dtso and .dtbo were not popular, so I'm
going to drop this patch instead of continuing to try to get it
accepted.

AFAICT .dtbo is moderately well established, and I think it's a good
convention, since it matters whether a blob is an overlay or base
tree, and it's not trivial to tell which is which.

Indeed.

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.dtso is much more recent,

Is it?

Well, I wouldn't bet money on it, I just seem to remember encountering
.dtbo for some time before .dtso was mentioned.

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The oldest reference I could find is from May 2015:
"[PATCH/RFC] kbuild: Create a rule for building device tree overlay objects"
https://lore.kernel.org/linux-devicetree/1431431816-24612-1-git-send-email-geert+renesas@glider.be/ (local)

Hm, I think .dtbo is even older than that, but again, I wouldn't swear
to it.

Sure. My work is based on Pantelis' work for BeagleBoard capes.
His code (from 2013?) used .dtbo and .dts:

    overlay/v3.10/merge:firmware/Makefile:$(obj)/%.dtbo: $(obj)/%.dts
| $(objtree)/$(obj)/$$(dir %)

So I might be the one who introduced .dtso...

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I have always used dtbo/dtso in my published overlays branches,
referred from https://elinux.org/R-Car/DT-Overlays, and used by
various people.

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and I think there's much less value to it.

IMHO the same reasoning as for dtb vs. dtbo applies to dts vs. dtso.
It matters if the resulting blob will be an overlay or base tree,
as the blob will have to be called .dtb or .dtbo.
As dtc outputs to stdout by default, the caller has to provide the
output filename, and thus needs to know.
Even if dtc would name the output file based on the presence of
"/plugin/" in the input file, the build system still needs to know
for dependency tracking.

Hm, fair point.  I was thinking of the the /plugin/ tag as the
distinction, whereas dtb is binary and the distinction isn't even
marked in the header.  But you're right that even readable text labels
inside the file don't really help make(1).  So, I retract that
assertion.

Thanks!

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We also do have .dts vs. .dtsi.

In the mean time, we're at rc7 again?

That was v5.13-rc7. Now we're at v5.14-rc7...

Will we live with the inability to e.g. let make distinguish between
DT includes and overlays forever?

I guess this is not gonna happen, so I'll convert all my overlays
from .dtso to .dts....

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson