Re: [PATCH 06/11] dts: bindings: Document device tree bindings for ETE

[Suzuki K Poulose]

Hi Rob,

On 1/3/21 5:02 PM, Rob Herring wrote:
> On Wed, Dec 23, 2020 at 03:33:38PM +0530, Anshuman Khandual wrote:
> > From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> >
> > Document the device tree bindings for Embedded Trace Extensions.
> > ETE can be connected to legacy coresight components and thus
> > could optionally contain a connection graph as described by
> > the CoreSight bindings.
> >
> > Cc: devicetree@xxxxxxxxxxxxxxx
> > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Cc: Mike Leach <mike.leach@xxxxxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > ---
> >   Documentation/devicetree/bindings/arm/ete.txt | 41 +++++++++++++++++++++++++++
> >   1 file changed, 41 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/arm/ete.txt
>
> Bindings are in schema format now, please convert this.

Sure, will do that.

> > diff --git a/Documentation/devicetree/bindings/arm/ete.txt b/Documentation/devicetree/bindings/arm/ete.txt
> > new file mode 100644
> > index 0000000..b52b507
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/ete.txt
> > @@ -0,0 +1,41 @@
> > +Arm Embedded Trace Extensions
> > +
> > +Arm Embedded Trace Extensions (ETE) is a per CPU trace component that
> > +allows tracing the CPU execution. It overlaps with the CoreSight ETMv4
> > +architecture and has extended support for future architecture changes.
> > +The trace generated by the ETE could be stored via legacy CoreSight
> > +components (e.g, TMC-ETR) or other means (e.g, using a per CPU buffer
> > +Arm Trace Buffer Extension (TRBE)). Since the ETE can be connected to
> > +legacy CoreSight components, a node must be listed per instance, along
> > +with any optional connection graph as per the coresight bindings.
> > +See bindings/arm/coresight.txt.
> > +
> > +** ETE Required properties:
> > +
> > +- compatible : should be one of:
> > +	"arm,embedded-trace-extensions"
> > +
> > +- cpu : the CPU phandle this ETE belongs to.
>
> If this is 1:1 with CPUs, then perhaps it should be a child node of the
> CPU nodes.

Yes, it is 1:1 with the CPUs. I have tried to keep this aligned with that of
"coresight-etm4x". The same driver handles both. The only reason why this
was separated from the "coresight.txt" is to describe the new configurations
possible (read, TRBE).

That said, I am happy to move this under the CPU, if Mathieu is happy with
the diversion.

Thanks for the review.

Suzuki