Date:   Fri, 16 Sep 2022 17:21:09 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] kbuild: take into account DT_SCHEMA_FILES changes while
 checking dtbs

On Fri, 16 Sept 2022 at 04:10, Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> On Thu, Sep 15, 2022 at 8:40 PM Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
> >
> > On Thu, 15 Sept 2022 at 07:51, Masahiro Yamada <masahiroy@...nel.org> wrote:
> > >
> > > On Sun, Sep 11, 2022 at 2:36 AM Dmitry Baryshkov
> > >
> > > <dmitry.baryshkov@...aro.org> wrote:
> > > >
> > > > On Thu, 4 Aug 2022 at 18:27, Rob Herring <robh+dt@...nel.org> wrote:
> > > > >
> > > > > On Fri, Jul 29, 2022 at 1:46 AM Dmitry Baryshkov
> > > > > <dmitry.baryshkov@...aro.org> wrote:
> > > > > >
> > > > > > On Fri, 29 Jul 2022 at 10:05, Masahiro Yamada <masahiroy@...nel.org> wrote:
> > > > > > >
> > > > > > > On Fri, Jul 29, 2022 at 3:53 PM Dmitry Baryshkov
> > > > > > > <dmitry.baryshkov@...aro.org> wrote:
> > > > > > > >
> > > > > > > > On Fri, 29 Jul 2022 at 08:55, Masahiro Yamada <masahiroy@...nel.org> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, Jul 28, 2022 at 2:36 AM Rob Herring <robh+dt@...nel.org> wrote:
> > > > > > > > > >
> > > > > > > > > > On Wed, Jul 27, 2022 at 4:06 AM Dmitry Baryshkov
> > > > > > > > > > <dmitry.baryshkov@...aro.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@...aro.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
> > > > >
> > > > > Not really a fan of the thousands of files that creates. Maybe if it
> > > > > was turned into something useful like a list of schemas that apply to
> > > > > the dtb. IOW, a dependency list. That would speed up re-running after
> > > > > a schema change. Though if a schema change created new dependencies,
> > > > > that wouldn't work.
> > > > >
> > > > > > >         $(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.
> > > > > >
> > > > > > It's up to you and Rob, but I'd really prefer a simpler solution here.
> > > > > > Regenerating dtbs sounds like a minor pain compared to hacking the
> > > > > > top-level Makefile again. What I really like is that if one has
> > > > > > CHECK_DTBS=y (for whatever reason), he can not generate dtb without
> > > > > > validation.
> > > > >
> > > > > I lean towards just rebuilding the dtbs. That's pretty quick and
> > > > > ensures we get dtc warnings with schema warnings. In the long run, I
> > > > > would like to make the schema checks not optional to run. The
> > > > > impediment to doing that is lots of warnings (but not not some
> > > > > platforms), adding a tool dependency, and validation time.
> > > >
> > > > Rob, Masahiro, do we have any conclusion here? I can change my patch,
> > > > but I'd like to understand in which way I should change it.
> > > > Fixing/testing yaml changes is a bit painful w/o this change.
> > > >
> > > > --
> > > > With best wishes
> > > > Dmitry
> > >
> > >
> > >
> > >
> > > I am fine with the patch as long as you fix DTC/CHECK to DTC.
> >
> > Ack, I completely forgot about this part. Please excuse me. I'll
> > change it to DTC_CHK (as suggested before) to fit into 7 chars in v2.
> >
> > >
> > > Another idea is to re-check the schema every time,
> > > like this:
> >
> > I think this will add the external build dependency. We tried a
> > similar approach several releases ago and had to revert the change.
>
>
> If you are talking about
> 75e895343d5a2fcbdf4cb3d31ab7492bd65925f0,
> you are completely misunderstanding.
>
> Look at my code closely.
> It is how the sparse checker works with C=2.

Ah, I see. Then I'm fine with either your patch or mine v2 at your
(and Rob's) preference.

> > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> > > index 3fb6a99e78c4..9fc9f39fb12e 100644
> > > --- a/scripts/Makefile.lib
> > > +++ b/scripts/Makefile.lib
> > > @@ -375,13 +375,9 @@ quiet_cmd_dtb_check =      CHECK   $@
> > >        cmd_dtb_check =  $(DT_CHECKER) $(DT_CHECKER_FLAGS) -u
> > > $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA
> > > ) $@ || true
> > >  endif
> > >
> > > -define rule_dtc
> > > -       $(call cmd_and_fixdep,dtc)
> > > -       $(call cmd,dtb_check)
> > > -endef
> > > -
> > >  $(obj)/%.dtb: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
> > > -       $(call if_changed_rule,dtc)
> > > +       $(call if_changed_dep,dtc)
> > > +       $(call cmd,dtb_check)
> > >
> > >  $(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
> > >         $(call if_changed_dep,dtc)
> > >
> > >


-- 
With best wishes
Dmitry

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