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From:   Rob Herring <robh@kernel.org>
Date:   Thu, 13 Jan 2022 20:10:11 -0600
Message-ID: <CAL_JsqKTckMABk6cM8d=boZcHyLdcqYmbzfKDjAHdCXoCPSDtg@mail.gmail.com>
Subject: Re: [PATCH 1/1] of: unittest: rename overlay source files from .dts
 to .dtso
To:     Frank Rowand <frowand.list@gmail.com>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        David Gibson <david@gibson.dropbear.id.au>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Michal Simek <michal.simek@xilinx.com>,
        Anmar Oueja <anmar.oueja@linaro.org>,
        Bill Mills <bill.mills@linaro.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-kbuild <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>
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On Thu, Jan 6, 2022 at 11:23 AM Frank Rowand <frowand.list@gmail.com> wrote:
>
> Hi Rob, David,
>
> 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...

> 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.

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.

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

Rob

>
> -Frank
>
>
> On 1/6/22 3:00 AM, Geert Uytterhoeven wrote:
> > On Tue, Aug 24, 2021 at 11:20 AM Geert Uytterhoeven
> > <geert@linux-m68k.org> wrote:
> >> On Tue, Jun 22, 2021 at 11:44 AM Geert Uytterhoeven
> >> <geert@linux-m68k.org> wrote:
> >>> On Sat, May 29, 2021 at 12:16 PM Geert Uytterhoeven
> >>> <geert@linux-m68k.org> wrote:
> >>>> On Sat, May 29, 2021 at 7:16 AM David Gibson
> >>>> <david@gibson.dropbear.id.au> wrote:
> >>>>> 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
> >>>>>> <david@gibson.dropbear.id.au> wrote:
> >>>>>>> On Wed, May 26, 2021 at 04:21:48PM -0500, Frank Rowand wrote:
> >>>>>>>> On 5/26/21 1:11 AM, Viresh Kumar wrote:
> >>>>>>>>> On 22-04-21, 13:54, Frank Rowand wrote:
> >>>>>>>>>> On 4/22/21 3:44 AM, Geert Uytterhoeven wrote:
> >>>>>>>>>>> On Mon, Mar 29, 2021 at 9:23 PM Frank Rowand <frowand.list@gmail.com> wrote:
> >>>>>>>>>>>> On 3/27/21 12:40 PM, Rob Herring wrote:
> >>>>>>>>>>>>> On Wed, Mar 24, 2021 at 05:37:13PM -0500, frowand.list@gmail.com wrote:
> >>>>>>>>>>>>>> From: Frank Rowand <frank.rowand@sony.com>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> 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.
> >>>>>>
> >>>>>>> .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.
> >>>>>
> >>>>>> 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/
> >>>>>
> >>>>> 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...
> >>>>
> >>>>>> 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.
> >>>>>>
> >>>>>>> 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!
> >>>>
> >>>>>> 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....
> >
> > Gr{oetje,eeting}s,
> >
> >                         Geert
> >
> > --
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> >
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds
> >
>