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Subject: Re: [PATCH] dt-bindings: Improve validation build error handling
To:     Rob Herring <robh@kernel.org>, devicetree@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Masahiro Yamada <yamada.masahiro@socionext.com>
References: <20191113210544.1894-1-robh@kernel.org>
From:   Jeffrey Hugo <jhugo@codeaurora.org>
Message-ID: <30b73f89-1ba1-6052-53bd-414ebdfa142c@codeaurora.org>
Date:   Thu, 14 Nov 2019 08:21:35 -0700
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On 11/13/2019 2:05 PM, Rob Herring wrote:
> Schema errors can cause make to exit before useful information is
> printed. This leaves developers wondering what's wrong. It can be
> overcome passing '-k' to make, but that's not an obvious solution.
> There's 2 scenarios where this happens.
> 
> When using DT_SCHEMA_FILES to validate with a single schema, any error
> in the schema results in processed-schema.yaml being empty causing a
> make error. The result is the specific errors in the schema are never
> shown because processed-schema.yaml is the first target built. Simply
> making processed-schema.yaml last in extra-y ensures the full schema
> validation with detailed error messages happen first.
> 
> The 2nd problem is while schema errors are ignored for
> processed-schema.yaml, full validation of the schema still runs in
> parallel and any schema validation errors will still stop the build when
> running validation of dts files. The fix is to not add the schema
> examples to extra-y in this case. This means 'dtbs_check' is no longer a
> superset of 'dt_binding_check'. Update the documentation to make this
> clear.
> 
> Cc: Jeffrey Hugo <jhugo@codeaurora.org>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Signed-off-by: Rob Herring <robh@kernel.org>

I injected a syntax error into a random binding file, and compared the 
output with and without this patch.  This patch makes a massive 
improvement in giving the user the necessary information to identify and 
fix issues.  Thanks!

Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>

> ---
>   Documentation/devicetree/bindings/Makefile  | 5 ++++-
>   Documentation/devicetree/writing-schema.rst | 6 ++++--
>   2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/Makefile b/Documentation/devicetree/bindings/Makefile
> index 5138a2f6232a..646cb3525373 100644
> --- a/Documentation/devicetree/bindings/Makefile
> +++ b/Documentation/devicetree/bindings/Makefile
> @@ -12,7 +12,6 @@ $(obj)/%.example.dts: $(src)/%.yaml FORCE
>   	$(call if_changed,chk_binding)
>   
>   DT_TMP_SCHEMA := processed-schema.yaml
> -extra-y += $(DT_TMP_SCHEMA)
>   
>   quiet_cmd_mk_schema = SCHEMA  $@
>         cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(real-prereqs)
> @@ -26,8 +25,12 @@ DT_DOCS = $(shell \
>   
>   DT_SCHEMA_FILES ?= $(addprefix $(src)/,$(DT_DOCS))
>   
> +ifeq ($(CHECK_DTBS),)
>   extra-y += $(patsubst $(src)/%.yaml,%.example.dts, $(DT_SCHEMA_FILES))
>   extra-y += $(patsubst $(src)/%.yaml,%.example.dt.yaml, $(DT_SCHEMA_FILES))
> +endif
>   
>   $(obj)/$(DT_TMP_SCHEMA): $(DT_SCHEMA_FILES) FORCE
>   	$(call if_changed,mk_schema)
> +
> +extra-y += $(DT_TMP_SCHEMA)
> diff --git a/Documentation/devicetree/writing-schema.rst b/Documentation/devicetree/writing-schema.rst
> index 3fce61cfd649..efcd5d21dc2b 100644
> --- a/Documentation/devicetree/writing-schema.rst
> +++ b/Documentation/devicetree/writing-schema.rst
> @@ -133,11 +133,13 @@ binding schema. All of the DT binding documents can be validated using the
>   
>       make dt_binding_check
>   
> -In order to perform validation of DT source files, use the `dtbs_check` target::
> +In order to perform validation of DT source files, use the ``dtbs_check`` target::
>   
>       make dtbs_check
>   
> -This will first run the `dt_binding_check` which generates the processed schema.
> +Note that ``dtbs_check`` will skip any binding schema files with errors. It is
> +necessary to use ``dt_binding_check`` to get all the validation errors in the
> +binding schema files.
>   
>   It is also possible to run checks with a single schema file by setting the
>   ``DT_SCHEMA_FILES`` variable to a specific schema file.
> 


-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.