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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Fri, 29 Jul 2022 16:03:43 +0900
Message-ID: <CAK7LNAQU42fpqPqUipZYx+685B+Rc8JGdaKcP3TdfQWUept1nQ@mail.gmail.com>
Subject: Re: [PATCH] kbuild: take into account DT_SCHEMA_FILES changes while
 checking dtbs
To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>
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Precedence: bulk

On Fri, Jul 29, 2022 at 3:53 PM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
>
> On Fri, 29 Jul 2022 at 08:55, Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Thu, Jul 28, 2022 at 2:36 AM Rob Herring <robh+dt@kernel.org> wrote:
> > >
> > > On Wed, Jul 27, 2022 at 4:06 AM Dmitry Baryshkov
> > > <dmitry.baryshkov@linaro.org> wrote:
> > > >
> > > > It is useful to be able to recheck dtbs files against a limited set of
> > > > DT schema files. This can be accomplished by using differnt
> > > > DT_SCHEMA_FILES argument values while rerunning make dtbs_check. However
> > > > for some reason if_changed_rule doesn't pick up the rule_dtc changes
> > > > (and doesn't retrigger the build).
> > > >
> > > > Fix this by changing if_changed_rule to if_changed_dep and squashing DTC
> > > > and dt-validate into a single new command. Then if_changed_dep triggers
> > > > on DT_SCHEMA_FILES changes and reruns the build/check.
> > > >
> > > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > > > ---
> > > >  scripts/Makefile.lib | 14 ++++++--------
> > > >  1 file changed, 6 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> > > > index c88b98b5dc44..3df470289382 100644
> > > > --- a/scripts/Makefile.lib
> > > > +++ b/scripts/Makefile.lib
> > > > @@ -383,17 +383,15 @@ DT_CHECKER_FLAGS ?= $(if $(DT_SCHEMA_FILES),-l $(DT_SCHEMA_FILES),-m)
> > > >  DT_BINDING_DIR := Documentation/devicetree/bindings
> > > >  DT_TMP_SCHEMA := $(objtree)/$(DT_BINDING_DIR)/processed-schema.json
> > > >
> > > > -quiet_cmd_dtb_check =  CHECK   $@
> > > > -      cmd_dtb_check =  $(DT_CHECKER) $(DT_CHECKER_FLAGS) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@ || true
> > > > +quiet_cmd_dtb =        DTC/CHECK   $@
> > >
> > > This is supposed to be 7 chars or less. DTCCHK or DTC_CHK perhaps. Or
> > > always do just 'DTC'. I can fixup when applying.
> > >
> > > I'll give it a few days for other comments.
> >
> >
> >
> > When you change DT_SCHEMA_FILES, re-running dt-validate should be enough.
> > You do not need to re-run dtc.
> >
> > I guess the strangeness comes from the fact that you are trying to do the
> >  two different things in a single rule.
>
> The issue is that with the current rules the dt-validate isn't
> re-executed on DT_SCHEMA_FILES changes. Thus comes my proposal.

Correct.


What I said is like this.


# touch the timestamp file, %.dtb.checked
$(obj)/%.dtb.checked: $(obj)/%.dtb $(DT_TMP_SCHEMA) FORCE
        $(call if_changed_rule,dtb_check)

$(obj)/%.dtb: $(src)/%.dts $(DTC) $FORCE
        $(call if_changed_rule,dtc)

$(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
        $(call if_changed_dep,dtc)


With the dtc/check split, we can avoid unneeded regeneration of
%.dtb when DT_TMP_SCHEMA or DT_SCHEMA_FILES is
changed.


One drawback is we track %.dtb.checked and and %.dtb separately,
so something like 53182e81f47d4ea0c727c49ad23cb782173ab849
may come back.


BTW, we do not check %.dtbo, why?

At least, 53182e81f47d4ea0c727c49ad23cb782173ab849
was trying to check %.dtbo


> --
> With best wishes
> Dmitry


-- 
Best Regards
Masahiro Yamada