Re: [PATCH RFC] interconnect: Add interconnect_graph file to debugfs

Re: [PATCH RFC] interconnect: Add interconnect_graph file to debugfs

[Leonard Crestez]

On 14.11.2019 04:41, Greg Kroah-Hartman wrote:
> On Thu, Nov 14, 2019 at 02:50:49AM +0200, Leonard Crestez wrote:
>> The interconnect graphs can be difficult to understand and the current
>> "interconnect_summary" file doesn't even display links in any way.
>>
>> Add a new "interconnect_graph" file to debugfs in the graphviz "dot"
>> format which describes interconnect providers, nodes and links.
>>
>> The file is human-readable and can be visualized by piping through
>> graphviz. Example:
>>
>> ssh $TARGET cat /sys/kernel/debug/interconnect/interconnect_graph \
>> 	| dot -Tsvg > interconnect_graph.svg
> 
> You might want to document this somewhere so we don't all have to go dig
> it out of the changelog every time we want to look at this file.

Files from sysfs are all described under Documentation/ABI but there's 
nothing similar for debugfs (and this should definitely not be 
considered ABI).

Maybe Documentation/driver-api/interconnect.rst should have a "debugfs 
interfaces" paragraph?

>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>> ---
>>   drivers/interconnect/core.c | 66 +++++++++++++++++++++++++++++++++++++
>>   1 file changed, 66 insertions(+)
>>
>> Example output as a github gist:
>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgist.github.com%2Fcdleonard%2F2f74a7efe74587e3d4b57cf7983b46a8&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7C946b54955bda47a2c7a308d768ac2d23%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637092961007878684&amp;sdata=Uk7QI%2FOo70H4H5N3ZZl2IMXMHMvP3vov%2FqSMnPuNWg8%3D&amp;reserved=0
>>
>> The qcs404 driver was hacked to probe on imx, the links to "0" seem to
>> from incorrect trailing 0s on DEFINE_QNODE. Possibly fallout from
>> switching to ARRAY_SIZE(__VA_ARGS__)?
>>
>> I'm not sure that "graphviz" is allowed as an output format even in
>> debugfs.
> 
> Why not!  :)
> 
> This is great, I love it, nice job, no objection from me.
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>