Re: [PATCH v2] dtc: create tool to diff device trees

From: Frank Rowand
Date: Mon Jan 11 2016 - 02:56:57 EST

On 1/10/2016 6:37 PM, David Gibson wrote:
> On Thu, Jan 07, 2016 at 11:03:14AM -0800, Frank Rowand wrote:
>> From: Frank Rowand <frank.rowand@xxxxxxxxxxxxxx>
>> Create script to diff device trees.
>> The device tree can be in any of the forms recognized by the dtc compiler:
>> - source
>> - binary blob
>> - file system tree (from /proc/devicetree)
>> If the device tree is a source file, then it is pre-processed in the
>> same way as it would be when built in the linux kernel source tree
>> before diffing.
>> Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxxxxxxxx>
>> ---
>> Tools to develop and debug device tree are somewhat inadequate. This is a
>> small step in improving the situation.
>> Rationale for and examples of using the script are provided in slides
>> 1 - 78 of the elce 2015 presentation "Solving Device Tree Issues",
>> which can be found at:
>> (The script was named dtdiff instead of dtx_diff in the presentation.)
>> Changes in v2:
>> - Remove dt-bindings from list of includes in cpp_flags
>> - Remove arch_dtc_flags, which were generated from the arch specific
>> dts makefile
>> - Reformat to 8 character tabs
>> - compile_to_dts(): added back missing return for binary blob
>> scripts/dtc/dtx_diff | 343 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 343 insertions(+)
>> Index: b/scripts/dtc/dtx_diff
> I think this is probably the wrong directory to put this in. Because
> it preprocesses in the style of the kernel, this script belongs in the
> kernel tree, not the upstream dtc tree. However, basically everything
> else in this directory is imported directly from upstream dtc.
> Putting this kernel-specific file in here will probably make updates
> to newer upstream dtc versions more complicated.

I agree with the concern (and had the same concern when I made the choice).

One thing that makes me more comfortable with the location is that the files
in the directory are updated with scripts/dtc/, which
explicitly lists which files it copies into the Linux tree. But even with
that, I still admit to some discomfort with the location.

Without getting too deeply into bike shedding, does anyone have a better
location? And keep in mind that there are several more tools coming in
the pipeline that would likely end up in the same location.

< snip >